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RICE IN THE UNITED STATES: VARIETIES AND PRODUCTION
Agriculture Handbook No. 289
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Agricultural Research Service
U.S. DEPARTMENT OF AGRICULTURE RICE IN THE UNITED STATES: VARIETIES AND PRODUCTION
l/4epé4á^í¿aled^aff¿^ POI-LOW THE LABEL
u s. eeritiMiNT OF A&IKULTUIE
Agriculture Handbook No. 289
Agricultural Research Service
U.S. DEPARTMENT OF AGRICULTURE
IsHued 196« Washington, D.C.
For sole by the Superintendent of Documents. U.S. Government Printing Office. Washington. D.C. 20402 Price .$1. CONTRIBUTORS
C. ROY ADAIR, leader, Rice Investigations, Crops Research T. H. JOHNSTON, research agronomist, Crops Research Division, Agricultural Research Service, Beltsville, Division, Agricultural Research Service, Stuttgart Md. Ark. J. G. ATKINS, plant pathologist. Crops Research Division, D. S. IMiKKELSEN, associate agronomist. University of Agricultural Research Service, Beaumont. Tex. California, Davis, ('alif. H. M. BEACHELL, formerly, researcli agronomist, (^rops M. D. MILLER, assistant state director, Agricultural Ex- Research Division, Agricultural Research Service. tension Service, University of California, Davis, Beaumont, Tex. ; now, plant breeder. Varietal Im- Calif. provement Department, International Rice Research Institute, Los Banos, Philippines. W. C. SHAW, formerly, leader. Weed Investigations in N. S. EvATT, associate agronomist, Rice-Pasture Research Agronomic Crops, Crops Research L)ivision, Agricul- and Extension Center, Texas Agricultural Experi- tural Research Service, Beltsville, Md. ; now, interde- ment Station, Beaumont, Tex. partmental pesticides coordinator, U.S. Department T. R. EVERETT, formerly, leader. Rice Insects Investiga- of Agriculture, Washington, D.C. tions, Entomolog^^ Researcli Division, Agricultural R. J. SMITH, JR., research agronomist, Crops Research Research Service, Baton Rouge, La. : now, associate Division, Agricultural Research Service, Stuttgart, professor, Louisiana State Universitv. Baton Rouire Ark. La. J. R. THYSELL, formerly, research agronomist, Crops Re- V. E. GREEN. JR., associate agronomist, p]verglades Ex- search Division, Agricultural Research Service, Biggs, periment Station, Florida Agricultural Experiment <'alif. ; now, agronomist. Crops Research Division, Station, Belle Glade, Fla. Agricultural Research Service, Brookings, S. Dak, NELSON E. JODON, research agronomist. Crops Research B. D. WEBB, research chemist. Crops Research Division, Division, Agricultural Research Service. Crowlev. La. Agricultural Research Service, Beaumont, Tex.
Trade names are used in this publication solely for the purpose of providing specific information. Mention of a trade name does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture or an endorsement by the Department over other products not mentioned. CONTENTS Introduction 1 Fertilizers 69 History of rice in the United States 1 Southern rice area 69 Distribution of rice in the United States 3 California 71 Acreage, yield, and production of rice in the Selected references 72 United States 3 Culture 74 Selected references 4 Rotation or cropping systems 74 Distribution and origin of species, botany, and Arkansas 75 genetics 5 Louisiana 76 Distribution of the species of Oryza and origin Mississippi 77 of cultivated rice 5 Missouri 78 Description and development of the rice plant Texas 78 and classification of cultivated varieties 6 California 79 Description of plant 7 Land leveling and seedbed preparation 79 Development of plant 8 Land grading and leveling 79 Classification of varieties 9 Seedbed preparation 81 Genetics 9 Seedbed preparation as related to method Selected references 16 of seeding 82 Rice breeding and testing methods in the United Construction of levees 83 States 19 Seed and seeding 84 History and objectives 19 Seed quality 84 Cultural methods and equipment for breeding Source of seed 85 rice in the United States 20 Seed treatment 85 Breeding methods 24 Time of seeding 86 Introduction 24 Rate of seeding 87 Selection 25 Method of seeding 88 Hybridization 25 Transplanting rice 91 Irradiation 28 Irrigating and draining 91 Breeding for agronomic characters 28 Amount of water required 92 Testing for milling, cooking, and processing Source of water 92 qualities 33 Quality of water 93 Milling quality 33 Water temperature and oxygen content 94 Cooking and processing qualities 35 Water control methods 95 Breeding for disease resistance 38 Water management 97 Blast 39 Draining for harvest 99 Brown leaf spot 39 Harvesting, drying, and storing 99 Narrow brown leaf spot 40 Harvesting 99 Straighthead 40 Drying and storing 103 White tip 40 Selected references 106 Hoja blanca 40 Weeds and their control 111 Description of varieties 42 Rice diseases 113 Short-grain varieties 42 Major diseases 113 Medium-.grain varieties 44 Blast 113 Long-grain varieties 45 Brown leaf spot 114 Other kinds of rice 47 Narrow brown leaf spot 114 Performance of varieties 47 Root rot 115 Choosing the variety 49 Seedling blight 116 Varietal response to seeding date 51 Stem rot 116 Results of tests with older varieties 51 Straighthead 117 Results of tests with newer varieties and White tip 117 selections 52 Minor diseases 118 Production of seed rice 56 Origin of high-quality seed rice 50 Bordered sheath spot 118 Classes of seed in a certification program, 56 Hoja blanca 118 Kernel smut 119 Cleaning, grading, and processing seed rice 59 Standards for seed certification 61 Kernel spots 119 Selected references 62 Leaf smut 119 Soils and fertilizers 65 Selected references 120 Types of soils used for rice production 65 Insects and their control 121 Arkansas 65 Rice water weevil 121 Louisiana 65 Rice stink bug 121 Texas 65 Grape colaspis 122 California 65 Other pests of rice 122 Chemistry of flooded soils 67 Selected references 124
111 RICE IN THE UNITED STATES: VARIETIES AND PRODUCTION INTRODUCTION By C. ROY ADAIK Eice, a leading cereal crop in many countries, ond i o Ri'azil in the AVestern Hemisphere. Other is grown on all continents. It often is considered leading rice-producing countries, outside of Asia to be a tropical crop, although it is grown in both and adjacent islands, are United Arab Republic the temperate and the tropical zones in Africa, (Egypt) and Malagasy Republic (Madagascar) Asia, Xorth America, Oceania, and South Amer- in Africa, and Italy and Spain in Europe. ica, and in the southern part of Europe. About 93 percent of the world rice crop was produced Rice yields yary widely among the rice-produc- in Asia during the 5-year period ending in 19(30 ing countries (table 1). Yields generally are (table 1). Only slightly more than 1 percent was nnich liigher in temperate than in tropical produced in the United States during this period. zones, not only because of diiferences in climate The United States is, howeyer, the leading rice- but also because of differences in cultural prac- producing country in North America and is sec- tices and in yarieties grown. TABLE 1.—Rice- acreage, production, and yield' per arre for each continent and selected' countries, averages for 5-year period. 1956-60 Continent and country Acreafre Production Yield
1,000 acres Million pounds Pounds per acre Asia 258,000.4 427,330.2 1,656 India 81,353.2 99,106.7 1,218 Japan 8,050.2 32,845.4 4,081 South America 8,091.6 12,496.2 1,544 Brazil 0,615.0 9,539.7 1,442 P»^ru - - 166.4 574.4 3,452 Africa 7,808.0 9,686.0 1,240 Coníío 400.0 392.C 982 United Arab RepubUo (Etiypt) 095.4 2,832.4 4,073 North America 2,825.0 6,985.3 2,473 Mexico 315.0 582.0 1,844 TTnited States 1,501.8 4,946.2 3,294 Eurooe 860.6 3.434.8 3,991 Italy 325.6 1,440.3 4,423 Spain 157.0 841.7 5,341 Oceania 117.2 330.9 2,823 Australia 50.2 240.7 4,795 World total 277,702.8 460,263.4 1,657
Source: U.S. Department of Agriculture, Agricultural Statistics: 1958, p. 21; 1959, p. 1960. p. 1961, p. 22.
History of Rice in the United States made in the prairie section of southwest Louisiana from 1884 to 1886 (7), and rice culture became Rice has been grown in the United States since established in that area about 1888. Production the latter part of the 17th century {;3)} Trial then increased rapidly in that part of Louisiana, plantings of rice were made in Virginia as early and in the adjacent part of Texas. Some rice was as 1609 (4). Apparently other plantings were grown along riyers in Arkansas in early years, made in the colonies along the South Atlantic but it did not become an important cash crop in coast from that time on, and ricegrowing was the State until after 1904 (P), when ricegrowing firmly established in South Carolina about 1090. was started in Grand Prairie. Experimental Until about 1890, rice in the United States was plantings were made near Butte Creek in the Sac- grown principally in the Southeastern States, al- ramento Valley in California in 1909 (5), and though some was grown along riyers in the South rice became established as a commercial crop in Central States. Experimental plantings were that area about 1912. Rice production has been 1 Italic numbers in parentheses refer to Selected Ref- of considerable importance in the delta area of erences, p. 4. Mississippi since about 1948 (2). AGRlCLíLTURE HANDBOOK 2 89, tl.S. DEPT. OF A(iRI(!ULïURE
ARKANSAS ARKANSAS CONT. CALIFORNIA LOUISIANA SECTION AND ACRES SOUTHWEST SECTION AND ACRES SECTION AND ACRES COUNTY Lo f a y e 11 e COUNTY PARISH NORTHEAST Linie River .... 2,000 SACRAMENTO VALLEY NORTH Clay 7,770 Miller Butle 55,202 Eost Corroll* -•5,267 Croigbeod 16,935 TOTAL ACRES... Coluso 74,125 ■430,061 Grant ••••185 Crittenden 6,439 ARKANSAS 1963 Glenn 40,846 Madison Cross 34,060 •••896 Placer 3,050 Faulkner 318 TEXAS Morehouse.*.. 5,949 Sacramento 10,126 Greene 5,406 West Carroll • • 1,185 SECTION AND ACRES Suiter 57,789 Independence 852 COUNTY Yolo 25,062 RIVER Jackson 20,200 EAST Lawrence g 251 Yubo 12,549 Ascension-^' •1,316 .... 559 Mississippi 1,505 SAN JOAQUÍN VALLEY Assumption - •••196 Chambers " Poinsell 38,400 •43,503 Fresno 20,818 Iberville ■• 323 Ho r d i n .... 54 Randolph 2,100 •- 1,004 Kern -• 3,435 Lafourcfie -•• Jasper Kings St. froncis 17,840 86 197 St. j om es ••• •1,472 While 1,140 Jefferson •• ■ 62,294 Modero ■••2,745 St. John •••- 1,436 Woodruff 19,760 Liberty 37,540 Merced •• 7,429 Tensos •• 126 Newton 731 Son Joaquin* •• 7,453 TECHE CENTRAL Oronge -• 4,972 Stanislaus-.. •• 2,260 Arkansas 76,150 CENTRAL Tulare .... 544 Avoy elles. 2,770 Clork 400 Br az 0 r ia• " -54,003 TOTAL ACRES Iberio 6,500 323,630 Con wo y 114 Ft. Bend"-- 19,203 CALIFORNIA 1963 Lafayette- • 9,530 ^la' Spring 4 70 GaI ves f 0 n " • 12,143 R 0 p i d e s • • • • •••574 iSSISSIPPI Jefferson 17,04 6 Harris 34,889 St. Martin- ■4,060 L" 8,395 Waller ■ 15,038 St. Mory-^^ • 3,100 COUNTY ACRES '■""f^e 39,000 WEST Bolivar ""airoc 14,000 Austin -.2,865 ,400 SOUTHWEST ''^"y 981 Coohoma Acodia ' 93,500 Co 1 h ou n -'•' •••4,287 664 ''''illips ■ 5,068 De Soto Allen •24,000 Colorado •-- •35,599 639 '''"'"'le 39,570 Hancock Beauregord •••* •• 4,943 Jackson •••- 184 Puloski 1,855 • 27,153 Colcasieu •65,088 Humphreys 935 Lavaco •••6,194 Leflore Cameron •13,337 SOUTHEAST Ma t ag 0 r d 0 - 874 •44,846 Evan geline • 39,640 Ashley 6,429 Quitmon 408 Victorio •• 5,083 S horkey Jeffe r son Da vi -95,692 Whar Ion-... ,150 '^'''"' 9,603 -52,740 St. Londry 16,945 Sunflower 300 ?,= ^*'a 14,000 Vcrmillion 114,800 ""''" 4,594 Tallohotche 510 TOTAL ACRES Lincoln 9,410 Täte 246 TEXAS 1963 ' •464,732 Tunica TOTAL ACRES 5,2,884 895 LOUISIANA 1963 Washington 427 TOTAL ACRES 50,632 MISSISSIPPI 196'3'
FluUKE 1.—: Distribution of the United States rice acreage in the principal producing States. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION
Distribution of Rice in the United States 2,250 Although rice is probably the leading food crop of the world, it is a major crop in the United 2,000 States in certain areas only. Rice production in the United States is centered in the Southern ,750 States of Arkansas, Louisiana, Mississippi, and Texas and in California. It is the principal cash crop in many counties and parishes (fig. 1). 1,500 - Small amounts of rice also are grown in Missouri, Oklahoma, South Carolina, and Tennessee. Some 1,250 rice has been grown in each of the States in Southeastern United States. In the United States, satisfactory rice crops 1,000 require (1) high temperature, especially rela- tively high mean temperatures during the grow- ing season; (2) a dependable supply of fresh 750 water for irrigation; (3) a terrain that is level enough to permit flood irrigation but that slopes 500 enough so that surface water can be readily drained; and (4) soil that will hold water well because of its fine texture, or a subsoil through 250 which loss by seepage is small (6). These cli- matic and soil conditions prevail in the areas where rice is grown in the United States. Rainfall and humidity during the growing sea- son are comparatively high in the Southern FIGURE 2.—Harvested acreage of rice in the United States, so less irrigation water is required there States (5-year annual moving average), 1899-1963. than in California (i). Irrigation water is sup- plied from streams, from reservoirs where water is impounded in winter and early spring, and moving average acreage increased each year until from wells. To produce optimum yields, proper 1955, when it was 2,106,000. The peak acreage of cultural practices must be followed. These prac- 2,550,000 was reached in 1954. The annual acre- tices include preparing a suitable seedbed, main- age then declined until 1957, when it was taining a uniform depth of irrigation water, 1,340,000. Starting in 1958, acreage increased providing sufficient soil nutrients for optimum slightly each year until 1963, when it was growth, and controlling insects and diseases and 1,765,000. weeds and grasses. Good-quality seed of adapted Yield per acre (fig. 3) in the United States in- varieties must be used to maintain quality and to creased from a 5-year annual moving average of produce high economical yields. For safe stor- 1,091 pounds per acre in 1899 to 3,563 pounds per age, the rice must be harvested at the right stage acre in 1963. This gradual increase in yield per and dried to the proper moisture level. acre has been brought about by improved cultural practices, such as better rotations, weed control, Acreage, Yield, and Production of Rice and irrigation and fertilization practices; better in the United States machinery, which led to improved and more time- In the 5-year period ending in 1963, Arkansas ly field operations; better methods of controlling produced 2Í.89 percent of the total United States diseases and insects; and improved varieties. rice crop; Louisiana, 24.26 percent; California, Average yields have fluctuated from year to year, 24.12 percent; Texas, 23.99 percent; Mississippi, with a long-term upward trend. However, there 2.47 percent ; and Missouri, 0.26 percent (S). The have been short periods when average yields de- United States has been self-sufficient in rice pro- clined. The 5-year annual moving average yield duction since 1917, and now is one of the leading per acre increased gradually from 1899 to 1940, rice-exporting countries of the world. but six times during this period the 5-year aver- Rice acreage in the United States (fig. 2) in- age yield was lower than that of the previous creased from a 5-year annual moving average of year. Yields declined from 1941 to 1945. Labor 301,000 acres in 1899 to 1,105,000 acres in 1922. and equipment were scarce during the war years, It then declined imtil 1936. The 5-year annual and the acreage was expanded to include some AGRICULTTTRE IIxVNDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE
production was 69.3 million bags, and the 5-year annual moving average was 59.3 million bapfs 3,500 (fig. 4).
3,000 Selected References
(1; ADAIK, C. R., and ENGLER, KYLE. 1955. THE IRRIGATION AND CULTURE OF RICE. lu Water, U.S. Dept. Agr. Yearbook of Agr pp. 380-394. 5 2,500 (2) MILLER, M. D., and BEACHELL, H. M. 1962. RICE IMPROVEMENT AND CULTURE IN THE UNITED STATES. Adv. in A^roD. 14: 61-108. (3) CHAMBLISS, C. E. 1912. A PRETJíMINARY REPORT ON RICE GROWING IN 2,000 THE SACRAMENTO VALLEY. U.S. Dept, Agr Bur. Plant Indus. Cir. 97, 10 pp. (4) GRAY, L. C, and THOMPSON, E. K. 1941. HISTORY OF AGRICULTURE IN THE SOUTHERN 5 1,500 U.S. TO 1860. Carnegie Inst. Wash. Pub. 430. [Reprinted in 2 v.] Peter Smith, New York. (5) HOLMES, G. K. 1912. RICE CROP OF THE UNITED STATES, 1712-1911. 1,000 - U.S. Dept. Agr., Bur. Statis. Cir. 34, 11 pp. (6) JONES, J. W., DOCKINS, J. O., WALKER, R. K., and DAVIS, W. C. 1952. RICE PRODUCTION IN THE SOUTHERN STATES. U.S. Dept. Agr. Farmers' Bui. 2043, 36 pp. ( 7) KNAPP, S. A. 1899 1929 1939 969 1899. THE PRESENT STATUS OF RICE CULTURE IN YEAR THE UNITED STATES. U.S. Dept. Agr., Bot. Div. Bui. 22, 56 pp. FIGURE 3.—Yield per acre of rice in the United States ( 8 ) UNITED STATES DEPARTMENT OF AGRICULTURE. (5-year annual moving average), 1S£M;^1963. 1968. RICE. ANNUAL MARKET SUMMARY, Yô^J. U.S. Agr. Market. Serv. AMS-277, 47 pp. (9) ViNCENHELLER, W. G. 1906. RICE GROWING IN ARKANSAS. Ark. Agr. Expt. Sta. Bui. 89, pp. 119-129. fields with p(X)r soil. These factors may have accounted for the lower yields in this periocl. The 5-year average yield per acre increased each year from 1946 through 1963. Higher rates of fertil- izer application and other improved cultural practices increased yields during this period. Production of rice (100-pound bags) in the United States in I7l8 was estimated to be over 79,000 bags of rough rice (J). Production in- creased to nearly 3.5 million bai^s in 1849. It then declined to about 637,000 bags by 1871. By 1899, production had increased to ^3.4 million bags. The 5-year annual production increased to 19.4 million bags in 1922. Production declined until 1926 and then increased slightly. However, it remained within the range of Í4 to 20 million bags until 1936. The annual production fluctu- ated from year to vear but with an upward trend during the period from 1937 to 1954 when pro- duction reached a high of 64.2 million bags. Annual production declined until 1958 and then KTGT RF 4.—Production of rice in the United States mcreased each year until 1963 when the annual (5-year annual moving average), 1899-1963. DISTRIBUTION AND ORIGIN OF SPECIES, BOTANY, AND GENETICS By C. ROY ADATR and NELSON E. JODON
Distribution of the Species of Oryza Tateoka (6'4) are listed in table 2. and Origin of Cultivated Rice Five species were reco^iized by Chatterjee [13) but not by Tateoka {6^ so they were not listed Species of Ori/sa have been reported from all in table 2. These are O. granulata Nees & Arn. continents except Europe and from many of the ex Hook, f.; 0. pereyinis Moench; 0. sativa L. hirger islands. Rosclievicz (53) ^ reported a com- var. fatua Prain; O. stapf i Roschev. ; and 0. prehensive study of the genus, and he concluded sxihvJata Nees. Four species were recognized by from his study that there were 20 species of Tateoka (6'4) but not by Chatterjee {13) so they Orysa.^ Chevalier {lo) reported a similar study were not listed in table 2. These are 0. angu^stJ' in which he recognized 22 species. Chatterjee folia Hubbard; 0. IjarthU A. Cheval.; 0. longi- i IS) later summarized the information on Ort/2a gluwis Jansen; and 0. rufpogen Griff. The and listed 28 species. Tateoka (64) summarized cliromosome number of the species of Oryza as the information on species of Oryza in 1968 and reported by Kihara (35) and the distribution as recognized 22 valid species. The 18 species that reported bv Chatterjee {14) also are shown in were recognized by both Chatterjee {13) and table 2. TABLE 2.—Species, chromosome rmmher. and elistriljiition of O rvza Chromo Species some Xc Distribution f2n)
1. 0. alta Swallen 24 and 4S South America and Central America. 2. 0. australiensis Domiii __ 24 Australia. 3. 0. brachyantha A. Cheval. ¿k Roelir. 24 West Tropical Africa and Central Africa. 4. 0. bre vil if/ida ta A. Cheval. (fc Roehr. 24 West Tr(»pical Africa. 5. 0. coarctata Roxb. 48 India and Burma. *3. 0. eichinrjeri Peter 48 East Africa. T. 0. [jlabrrrlma Steiid. 24 W>st Tropical Africa and Central America.^ S, 0. rjrandirjlumis fDoeU ) Prorloehl 24 and 48 South America. 9. 0. JatifoJia Desv. 48 Central America, South America, and West Indies. 10. 0. meyeriana (Zoll. *fc Mor.) I>aill. 24 .Java, Borneo, Philippines, and Siam. 11. 0. minuta Presl 48 Malay Peninsula, Philippines, Sumatra, Java, and Borneo. 12. 0. offlcinalis Wall, ex Watt __ 24 India and Burma, 13. 0. perrieri A. Camus ^ladagascar. 14. 0. punctata Kotschy ex Steiid. Northeast Tropical Africa. 15. 0. ridleyi Hook. f. I 48 ^lahiy PetiÍnsula, Siam, Borneo, and New Guinea. 16. 0. sativa L. 24 and 48 India and Indo-China. IT. 0. srlilechteri Pilger New Guinea. IS. 0. tisseranti A. Cheval. Cnntral Africa.
1 P.I. 269630. Collected in El Salvador by H. M. Beaohell and identitied l)y Eugf-iip Critlith, Crops Research 1 Mvision, Agricultural Research Service, Beltsville, Md., and J. R. Swallen, Smithsonian Institution, Washington, D.C. Rosclievicz (53) divided the species of Oryza tion and nomenclature of Oryza and recommended into four sections on the basis of morpholo (or /. spontanea RosclieA,:' uid 0. perenm's were duplicated, probably due to meiotic irregu- (Asiatic, American, and Afriraii) subspecies and hirities in the hybrid. This followed by a subse- varieties; (2) the relation of the form commonly ((uent doubling of the chromosomes attained the designated 0. stapfii to 0, glahemmu and 0. bre- secondary balance of n = 12, the present existing viUgulata; (3) the relation between 0. gramdata number of 0. sativa'''^ (4-^). f. and 0. imyerkma; (4) the relation between 0. Sampath and Rao {56) "inferred that Oryza alta and 0. grandiglumis; and (5) the status of perennis is the ancestral form of cultivated rices, the taxa previously designated 0. ubœnghemi>< having given rise to 0. sativa in Asia and 0. gla- Chev. and 0, malampuzhaensls Krish. and Chand. herrima in Africa by human selection." These The committee also believed that the form com- authors were of the opinion that 0, hreviligulata monly designated 0. subid at a should be excluded and 0. sativa var. fatua are of collateral descent irom Oryza and should be recognized as Rhyn- from O. perennis. The present types that are choryza subuhta (Nees) Baill. classified as O. sativa var. fatua or spoiitanea Chatter]ee (li) reviewed the literature on the show morphologic differences that may be due to origin and distribution of wild and cultivated genetic transfer from cultivated rice. From this rice. He concluded that the eastern part of it is inferred that these wild forms are derived India, Indo-China, and part of China could be from hybrids with cultivated rices and are not considered the area where cultivated rice {Oryza the progenitors of cultivated rice. Instead it has sativa) originated. Chatterjee further concluded, been strongly suggested {55, 56. 70) that an inter- as did Roschevicz (55), that for the genus as a mediate type may be the immediate ancestor of whole or the section Sativa Roschev., the center O. sativa-. of origin is Africa. He was of the opinion that 0, altas 0. aii^tralieiisis^ 0, hixichyantha, 0, Description and Development of the eichingeri^ 0, grandiglumis^ 0. latí folia, 0. mm- Rice Plant and Classification uta^ 0, pemeri, 0. schlechteH^ 0. subidata^ and 0. tisseranti had little part in the ancestry of cul- of Cultivated Varieties tivated rice. This view seems to be based either Cultivated varieties of (9. sativa are divided on the fact that these species do not cross with into groups on the basis of several characters. 0, sativa or on the fact that they occur naturally The principal division is on the basis of sterility in areas far removed from the center where rice of the hybrid. Kato and others {33, 31^) observed cultivation orimnated. that in crosses of certain varieties from the tem- Many investigators have studied and discussed perate zone and certain varieties from tropical the origin of the genus Oryza and of cultivated areas, the hybrids had a high percentage of sterile rice {13, U, 15, 35, 1^6, 1^8. 50, 53, 55, 56, 67, 70), florets. The hybrids between varieties within It is generally concluded that the original ances- these two groups were as fertile as self-pollinated tral species may no longer exist and that present parent varieties. varieties evolved through progressive stages from known wild species {56). They proposed that the temperate zone varieties be named japónica and the tropical zone varieties Nandi {U) and Sakai (5^) proposed that a indica. Kato and others {31^) observed no differ- species with a haploid number of five chromo- somes was the ancestor of Oryza. This proposal ence between japónica and indica varieties in chromosome number and behavior or in pollen was rather widely accepted. Nandi (^4) observed that in the somatic complement having 24 chro- formation. However, in the hybrid, pollen for- mosomes there were two members of eight types mation Avas abnormal. Serological investigations and four members of two types. The maximum showed differences between japónica and indica varieties. association in second metaphase was two groups of three and three groups of two. It was con- Later, Terao and Midusima {66) noted that cluded from this observation that the haploid another group of varieties, principally from trop- genome of the present 0. satina is composed of ical islands of Southeast Asia, were intermediate. two original five-paired species belonging to two This last group is referred to as bulu. different ancestral genomes in which two chro- It appeared from the earlier studies that the mosomes were duplicated. varieties could be divided into three distinct Later, Shastry, Rao, and Misra {60) identified groups based on sexual affinity. Mizushima {39), 12 pachytine bivalents in a strain of 0. sativa. however, determined that this was not true and based on their length and arm ratios. This find- that sexual affinities among varieties from these ing seems to cast considerable doubt on the val- groups varied gradually from one extreme to the idity of the supposition "that O. sativa is a sec- other. ondarily balanced allo-tetraploid which origin- Oka (^5) compared 147 varieties from widely ated through hybridization between two different different geographic areas on the basis of a num- five-paired species in which two chromosomes ber of morphologic and physiologic characters RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION and by observing sexual affinity in hybrids. From basis of chromosome structural differences, lethal these studies, he placed the 147 varieties tested o-enes, inversions, paracentric inversions, genie into indica (continental) and japónica (insular). nuitations, and cryptic structural hybridity. He subdivided the japónica gi^oup into ''tropical- There are many morphologic differences be- insular" and ''temperate-insuhir/' tween typical japónica, indica, and bulu varieties In a review on reports of sterility in hybrids (table 3). Varieties that are known to be pro- between indica and japónica varieties, Sliastry, genies of hybrids are intermediate in many Rao, and Misra (60) explained sterility on the respects. TABLE 3.—Characters of japanwa. indica, and hiiiu ri^e varieties Character Japónica Indica Bulu Grain shape Short Long . Large. Second foliar leaf : Length Short Long Long. Angle -_ _ Small La rire Small. Foliage color _ _ Dark green Lisrht srreen Light green. Culm : Stiffness _ - Stiff Not stiff Stiff Erectness Upright Sureadins" Upright. Length Short Long Long. Flag leaf : Angle Medium Upright Medium Shape Narrow and short Narrow and long Broad and long. Degree of emergence of upper node. Medium Well emerged Not emerged. Number of tillers Many Many Few Pubescence Pubescent Variable Víí riablp Awns None None Many Panicles : Number Many Many Few Weight Heavy Light Heavy Length Short Long Medium Density- Dense Medium Medium Branching of rachis Few Medium Many. Source: Nagai HO). Description of plant The leaves of the rice plant are flat and range from 7 to 20 milimeters wide. The coleoptile The principal parts of the rice plant are a usually is considered to be the first leaf. It has fibrous root system, cuhns, leaves, and panicles. stomata but few chloroplasts. The mature foliage The fibrous root system extends outward and leaf consists of the sheath at the base, which sur- downward from the base of the plant. Adventi- rounds the culm for some distance; the blade, tious roots that arise from the lower nodes of the which is set at an angle with the sheath; the culms are finely branched. The extent of the root ligule; and the auricles. The junction of the system and the size of the roots vary with variety sheath and blade often is called \h^ collar or and type of culture. junctura. The swollen zone at the base of the The culm and leaves develop from ih.^ plumule. sheath where it joins the culm is the pulvinus. The culm consists of the nodes, which have solid The panicle of most varieties is fairly dense centers (septum), and the intemodes, which are and drooping. There is, however, much inter- hollow. The culms of most varieties of Oryza varietal variation, since the panicle ranges from sativa are erect or ascending, although there are open to very compact and from erect to drooping. procumbent types. Varieties range in height From one to three or sometimes more branches from less than 15 to more than 96 inches (37 to arise alternately or somewhat in whorls at each 240 centimeters) although varieties grown in the node of the peduncle. The rachilla bears the United States range from 36 to 54 inches. The spikelet, and each rachilla arises on the same side culms vary in diameter at the base from 5 to 15 of the rachis. Each rachilla usually has a single millimeters. The number of nodes in the culm spikelet, although some varieties may have two or ranges from 13 to 16 (5^), and the number is more spikelets on a rachilla. The spikelet is significantly correlated with length of growing laterally compressed, is one flowered, and articu- season. Usually, four internodes elongate; the lates below the outer glume. upper internode (peduncle) is usually the long- The two outer glumes usually are short, that is, est, and it bears the panicle. less than one-third the length of the lemma, al- AGRICUl/l LHCE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE thoiio;h tliere are types that ]i;i\e uluines as lono; length of growing period of the variety {Jß). as the lemma or long-er. I1i<' lemma (inferior or Tillers develop from buds in the axil of the node k-)wer ñoweriiig ghime) is rigid, keeled, and three and the arrangement is alternate {32^ Jf9). Japón- nerved, and has' two additional thin, marginal ica varieties {32) develop secondary tillers from nerves that can be seen only in section. The the buds at nodes 3 or 4 to 10. Tillers from node apiculus or ti]) of the lennna is sometimes i)ro- 10 often do not produce panicles. Tertiary tillers longed to form the awn. The palea (snperior or may develop from buds at nodes of the secondary upper riowering glume) is similar to the lemma, tillers. Init narrower. It lias two nerves near the margin Panicle formation starts when all nodes have and a thin midnerve that can be seen only in sec- been formed. The length of the period from tion. The ñower is composed of a one-carpellate seeding or transplanting to the starting of panicle pistil with a bifurcated, plumose slender style; formation varies with the length of growing and six stamens with yelhnvish, four-lol)ed, two- period of the variety. The period up to forma- celled anthers. The principal parts of the cary- tion of the panicle primordium constitutes the opsis (brown rice) are the embryo and endo- ^'vegetative'' stage. It is this period that accounts sperm and the covering tissues. for the variation in length of growing period among varieties. Formation of the panicle pri- Development of plant mordium starts about 50 days after seeding for very early United States varieties and about 100 Rice seed germinates rapidly when moisture, days for later United States varieties. The pe- temperature, and oxygen are optimum. The em- riod from formation of the i^anicle primordium to bryo, which consists of the organs that develop to emergence of the panicle from the sheath ranges produce the rice plant, lies in a slanting position from 24 to 31 days for indica varieties {1^9) and at the base of the grain on one side of the endo- from 28 to 36 days for japónica varieties (5). sperm. The endosperm contains the stored food For indica varieties, the panicle primordium that nourishes the developing seedling until the can be noted when it is 0.125 to 0.25 millimeters roots have developed sufficiently to obtain nu- long. By the time it is 0.5 millimeters long, trients from the soil. ''hemispherical excrescences are observed at the At germination, the coleorhiza pushes through base" (45^). The hemispherical excrescences rep- the pericarp, leaving a cavity. The primary root resent the branches of the panicle. Rudiments of soon elongates, fills the cavity, and then pushes the spikelet on either side of the basal a^is are through the coleorhiza. The root extends upward perceptible when the panicle primordium is 5.0 for a short distance and then turns down. About millimeters long. The panicle primordium then this same time, the coleoptile emerges and rapidly elongates, and the spikelets are differentiated elongates. The epicotyl below the coleoptile also progressively from the tip down to the base of the elongates. Elongation varies with the depth the panicle. Spikelets in the tip and middle of the seed is planted. It elongates enough to l)ring the panicle have reached maximum length by the base of the coleoptile to the surface of the soil. time the panicle has completed its elongation, When the coleoptile emerges from the soil, it which is 15 to 20 days after formation of panicle splits on the side opposite the scutellum, and the primordium. The spikelets at the base of the foliage leaves soon appear. Usually in about 2 panicle complete their elongation by the time the days, two adventitious roots start t<) develop in panicle emerges from the sheath {Jf9), the meristematic zone on the side opposite the Similar results were reported for a variety from scutellum. A third adventitious root may appear the Philippines {30), Anthesis starts the first later at the coleoptile divergence opposite the two day of emergence of the panicle. It begins with older ones. Lateral roots soon develop from the the ñowers at the tip of the panicle and continues primary and adventitious roots {71), progressively at the tip of each branch of the The main axis of the plant, often called the panicle. The greatest number of flowers open primary tiller, is differentiated rapidlv. The the second or third day after the panicle emerges. meristematic region is at the base of the inter- Anthesis occurs over \\ period of 6 to 10 days, nodes; this is typical of all grasses. With three vaiwing with weather and variety. It usually early (130-day) United States varieties, tillering occurs from midmorning to shortly after noon. started within 3 weeks after germination, and all The time differs with variety, location, and tdlers that produced panicles were formed within weather (5, 52), Pollen is shed just before or at a 3-week period (4). Japónica varieties started the time the flower opens. to tiller about 14 days after transplanting and The formation and development of the embryo tillering was completed in 23 to 25 days (5í2). of a japónica variety {65) and of a variety from Indica varieties started to tiller about ^14 days tlie Philippines {30) has been described! The after transplanting, and all tillers were initiated process is similar in both varieties. Juliano and m 3 to 5 weeks from this time, depending on the Aldama {30) reported that "development of the RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 9 megasporange, megaspore mother cell, and em- Breediiig and Testing Methods in Ú\^ United bryo is normal and folloAvs very closely those States,'' p. 31.) reported by other investigators. The embrvo sac On the basis of chemical characters, rice types is of the normal octonncleate type/' These nives- are divided into waxy (glutinous; endosperm tigators also observed that ''clevelopment of the contains no amylose) arul conunon (ordinary microsporange is normal and follows those re- starchy; endosperm contains amylose as well as ported in many angiosperms" ; that '\livision of amylopectin). Only a very small acreage of the microsi:)ore mother cell is successive''; and waxy rice is grown in the United States. The that ''long before anthesis the young microspore })ercentage of amylose in the starch in the endo- contains two coats, a thin peripheral cytoplasm, sperm of varieties groAvn in the United States wherein a single nucleus is embedded, and a single varies rather widely. (''See Eice Breeding and germ pore." Double fertilization occurs about 12 Testing .Methods in the United States,'^ ]>. 38.) hours after anthesis (65). In a japónica variety, A more detailed system is needed to classify the the caryopses reach maximum length in about Í2 many varieties and lines used in breeding studies. days after flowering, maximum width or breadth Much work has been done to devise objective (dorsoventral diameter) in about 22 days, maxi- methods of classifying rice varieties. Previous mum thickness (lateral diameter) in about 2S work was summarized and a proposal for classi- days, and maximum dry weight in about 35 days fying rice varieties was formulated by a special (o7). Similar results were obtained for United committee in India {21), The committee pro- States varieties; air-dry kernel weight and per- posed that rice varieties be classified on the basis centage of germination were maximum about 35 of qualitative and quantitative characters. Nagai davs after the first panicles emero^ed from the {IfO) reviewed systems used to classify rice var- sheath (61). ieties. These systems were followed rather closely in the Food and Agriculture Organization, Classification of varieties ^'World Catalogue of Genetic Stocks—Eice,^' (i) and subsequent supplements. The classification Cultivated varieties of rice belong to the gemis system used in the laiited States includes the Oryza L., tribe Oryzeae, and family Gramineae. items in these systems with certain modification Most cultivated varieties are in the species Oryza and additions. sativa L., although varieties of the species 0. gJahemma are cultivated in Africa. 0. sativa, is Genetics an annual ; but when moisture and temperature are optimum and in the absence of disease, jilants Varieties of ordinary cultivated rice, being have survived and produced grain for 20 years largely self-pollinated, remain uniform and con- or more. stant if care is taken to preserve pure seed. Mu- All varieties of rice groAvn in the United States tations, chromosome changes, and natural cross- are in the species 0. sativa L. The commercial ing, however, have brought into existence a wide varieties are classified on the basis of (1) length diversity of types and varieties that aiïect every of growing season, (2) size and shape of the part and function of the plant. Plants may be grain, and (3) chemical character of the endo- short or tall enough to grow in deep water; may sperm. Ito and Akihama {22) further classified have colored pigments of various shades dis- varieties on the basis of plant height, straw tributed in different ^^atterns over the plant; may strength, disease resistance, and color of various tiller little or profusely; may have long and plant parts. slender or short and round grains, with or with- On the basis of length of growing season, out awns; and may have translucent or opacjue United States varieties grown in the Southern kernels that differ in chemical composition. Also, States are divided into four groups: (1) Very the life cycle of one plant may be three times as early (100-115 days); (2) early (116-130 days)^ long as that of another. (3) midseason (131-155 days) ; and (-1) late (150 Differences that can be sorted into distinct con- days or more). The length of growing season is trasting classes make possible the study of segre- somewhat longer in California than in the South. gation and recombination as well as linkage rela- The difference in length of growing season be- tionships of genes, which are the units of heredity. tween these two areas is caused by day lengtli For convenience in publishing genetic studies, and temperature. differences that have individual efforts great The LTnited States varieties are divided into enough to be recognized are assigned gene sjmi- three grain size and shape classes: short (Pearl), bols. To promote uniform usage among rice medium, and long. The more slender long-grain geneticists, the International Eice Commission of varieties sometimes are considered a fourth class. the Food and Agriculture Organization of the Examples of the respective groups are Caloro, United Nations has adopted and recommended Nato, Bluebonnet 50, and Kexoro. (See ^'Eice the gene symbols listed below {2), 10 AURK L LIUIU: nANI)P>()OK 2 8 9, U.S. DEPT. OF AGRIC'ULIXTRE Inherited differences, sucli as plaiii height, tluit FA ^- Early flowering (low photosensitiv- are not clear cut but tliat grade from one extreme ity ).- See Lf to another involve the interaction of several genes Kn- = Enhaneei' (intensifier). Precedes that have similar effects, but the actual number symbol of character affected and the individual contribution of the genes in- ei- -- erect growth habit, recessive to spreading or procumbent. See dw, la volved remain uncertain. Ex = Exerted vs. enclosed panicle Gene symbols adopted and recommended Egi- = Eragrant flower for rice ^ fs = fine stripe vr = long glume 2 exceeding % length of A the spikelet A, A^ a ^ allelic anthoeyanin activator Kcnes gh ^ goldhull (golden yellowhuU, reces- (compleiuentary action with C genes sive to straw eolor. ) See Wh prodiiees red or purple in apieulus) gl = glabrous (nonhairy) leaf. See Lh al -^ albino - Crm = semi-dominant long glume. More ex- An .= Awned - treme and less regular in expression ail = laidinientary aui'iele than g. Epistatie to g green and white stripe ; see fs, v. be --= ))i'ittle eulni Bd = Beaked hull (tip of lemma i-eeurved H (H or h is suggested to denote hull, i.e., over palea ) lemma and palea ) Bf = Brown furrow (dark brown eolor in H™, H', = allelic genes for nonanthocyanin col- furrows of lemma and palea). See ors of lemma and palea appearing only in the presence of Gh ; goldhull I-Bf =^ Inhibitor of dark brown furro^^' colors appear with gh bg = eoarse (l)ig) culms He -^ Hf'lmintliosporium resistance Bh = BlaekhuU (complementary genes)- hsp = huUspot bl = physiologir diseases showing dark brown or blaekish mottled discolora- I = positive vs. negative staining with tion of leaf iodine-potassium iodide solution bn — bent node—culm forms angle at node T- ^ inhibitor (precedes symbol of char- acter inhibited ) — allelic basic genes for anthoeyanin QBt pBr «•olor; highei" alíeles have pleiotropie ( K or k is suggested to denote kernel, expression in internode i.e., caryopsis) C alone ^^ tawny colored apieulus CA == red or purple colored apieulus (1 (as second letter of a symbol) is CAP = completely and fully purple colored suggested to denote leaf.) apieulus = lethal (precedes symbol of character En-C = Enhancer of C having lethal effect ) Ce = Cercos por (I resistance la =^ lazy. See er chl =^ chlorina (chlorophyll deticiency) Ld ~= Lodging Lf Cl = Clustered spikelets, also super clus- = Late flowering ( highly photosensi- ter tive).- See Ef els .= eleistoganious spikelets Ig = liguleless (auricle and collar also clw = claw-shaped spikelets. See tri and al)sent) ^ Bd Lh = very hairy (long hair) dominant to D ordinary pubescence. See gl .- dwarfs,^ al:M)Ut % to i/o height or Ik .= grain length (long grain) 2 normal ; discrete classes in segregat- Imx --= extra lemma ing populations hi = lutescent da -^ double awn Lx = Lax vs. normal panicle. See Dn Dn Lxo = Lax vs. compact = Dense or '^compact" ; very close ar- :\i i-angement of spikelets (vs. normal panicle) ; epistatie to Ur. See Lx me = multiple embryos (polyembryonie) also Cl mp = multiple pistils (polyearyoptic) Dno = Dense vs. lax mottled leaf ; see bl Dn¡ = Normal vs. lax N Dp = Depressed palea and underdeveloped nal = narrow leaf palea nl = neckleaf dw = deep water paddy, so-called floating nk or I-Nk ^ notched kernel rico () o = open hull (parted lemma and palea) /Reemnmended by the Eighth (1059) PAO Interna- (P (as first letter of a symbol) is sug- tional Rice Commission Working Party on Rice Produc- gested to denote anthoeyanin color.) tioii and Protection; the list includes present revisions Exceptions : Ph, Pi ^More than one gene involved; subscripts to be sup- = (V)mpletely purple apieulus (comple- mentary action with C and A) plied by workers as needed. Letter subscripts are sug- Pau gested for complementary genes, numeral subscripts for = Purple auricle, basic to Pig genes having phenotypically similar effects and also f (PuiTJle Red purple Red Pink Colorless Flowering. A (Purple Red purple Red Colorless do Maturity. jDeep red Red Orange tinge __ Orange tinge __ do Flowering, A^ [Brown Light brown __ Yellow tinge __ Colorless do Maturity. j Colorless Colorless Colorless Colorless do Flowering. a [Dark brown Brown Light brown Yellow tinge do Maturity. Source: Takahashi {62). Combinations of C and A are basic to the glumes (lemma and palea), leaves, and nodes was appearance of color in other parts of the plant as shown to result from the complementary action well as in the apiculus. Purple color of inner of C and A with Pr, PI, and Pn, respectively. 12 V(iRl( I LIURE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE The expected segTegatioii ratio ii» tlie Fo of a apiculus:! both bran and apiculus colorless. In cross between a line witli purple apicuhis and this cross, red bran is found only with colored inner glumes and a completely colorless line is apiculus and brown bran only with colorless. In given below to illustrate the many color patterns the cross C A Rd Re X c a rd Re, on the other That appear as the result of recombinations of hand, red bran occurs with and without colored color genes. apiculus; but brown bran never occurs with col- ored apiculus. The F2 ratio is 9 red bran, colored Ratio of Color patterns apiculus :8 brown bran, colorless apiculus :3 red ye tie eomhinations bran, colorless apiculus:! both bran and apiculus 27 C A Pr Purple apieiilus and glumes. colorless. 9 C A pr Purple apiculus, colorless glumes. The existence of varieties with life cycles that 9 C a Pr Brown (tawny) apiciUus and range from as short a period as 3 months to about glumes. 8 C a pr Brown (tawny) apiculus, colorless 10 months contributes greatly to the wide adapt- glumes. ability of rice to different areas and conditions. 1(3 (j All combinations with c are color- Varieties are classified for time of flowering as less. photosensitive or as insensitive. The photosen- Many of the seg:regation ratios previously re- sitive class includes late-maturing varieties, which ported in publications in Japan and other coun- remain in a vegetative stage while the days are tries can noAv be reinterpreted with fewer as- long but probably enter the flowering stage when sumptions in accordance with the above analysis. the night period reaches a critical length. In Other workers had recognized two basic comple- Ceylon, differences in varietal response to varia- mentary color genes, but the pleiotropic action tions of less than an hour in day length were and the existence of multiple allels had not been found and were controlled by one dominant gene fully realized. for sensitivity (11). Early varieties tend to enter Indian workers {50) have established an allelic the flowering stage after the completion of a series for another set of glume colors : H"^', fairly constant vegetative stage. mottled; W, piebald; H^, green changing to straw In Japan, a series of six maturity genes domi- at maturity; and H^ dark furrow color. These nant for lateness and having accumulative effects colors appear only in the presence of the gene for have been postulated (40). The action of these strawhull color, Gh; and witli gh, only goldhull genes is conditioned by temperature. Sampath colors appear. and Seshu (57) reported an Indian study that Purple bran appears in varieties apparently dealt witli crosses of two varieties from Japan lacking pigmentation in all other parts and seg- with photosensitive Indian varieties. One Japa- regates in 8:1 ratios in crosses witli colorless bran. nese variet}^ was insensitive and the other A cross between a purple bran line that carried a photosensitive in Japan; but under the tempera- gene for red bran and a colorless line gave 9 ture and day length conditions at Cuttack, India, purple-red :8 purple :3 red:l colorless (9)'. The both flowered early (48 and 68 days from seeding, red underlaid the purple m such a way that it respectively).^ The Fi plants of crosses of the was possible to separate the first two classes. A Indian varieties with the insensitive Japanese cross between a purple bran line having colorless variety flowered early, and segregation in the Fo vegetative parts and a line having ordinary bran generation was 3 early:! late^or !5 early:! late. and partly purple leaves segregated in the F. However, in crosses iDetween the photosensitive generation in a ratio of 18 colorless or partlv Japanese variety and Indian varieties the Fi purple leaves to 8 fully purple leaves. The plants flowered late and segregation in the Fo results show that an inhibitor gene restricts ex- generation was ! early :8 late or ! early :!5 late. pression of full purple leaf color. Purple leaf It was assumed that in the crosses with the photo- appeared only in the presence of purple bran. sensitive parent, genes involved in temperature Red rice varieties are grown in southern India, responses and modifying the photoperiodic re- in Ceylon, and in other areas: but red-rice mix- sponse were segregating. These authors cite a tures hi white milled rice detract from the Japanese study in which a gene for late flowering appearance. Work reported from Japan (47) was found to be epistatic to one for early showed that red bran color required tAvo genes flowering. for expression. A gene Re for brown bran is In Louisiana, a cross between varieties that basic, and with Rd the bran is bright red. Rd headed in 90 and !25 days was studied (8). The and A are closely linked; this makes it appear Fo segregation was bimodal and indicated the that the apiculus color gene is basic for red. In action of one major gene for earliness. a cross between a red line of the genetic constitu- Disease resistance can be analyzed genetically tion C A Rd Re and colorless C a rd re, the segre- if distinctly resistant and susceptible classes gation is 9 red bran, colored apiculus :8 coloi^ess occur. Specialized races of fungus diseases must bran, colored apiculus :8 brown bran, colorless be taken into account ; usually segregation is best RICE IN THE UNITED STxVlES : VARIETIES AND PRODUCTION 13 determined follo^Ying inoculation with cultured The strength of attachment of spikelets to their spores of individual races. Single and duplicate I)edicles is of practical importance to the groAver. genes for resistance to four racles of Ccrcosporn Sliattering (shedding) of grain in the Avind, orijzae I. Miyake, the fungus that causes narrow which occurs in red rice, Avould make it impos- brown leaf spot, have been determined {ß'7). Xo sible to harvest the crop; whereas at the other linkage was found between genes for Cercospora extreme, Avhich occurs in some of tlie Japanese resistance and the chromosome marker genes C varieties, the attachment is so tight that in com- apiculus color, W furrow color, gh goldhull, and bining much grain Avould remain on the straw. wx waxy {26). Types tliat thresh free of the straAv yet do not Several types of genetic segregation have been shatter easily are needed for mechanized harvest. reported for inheritance of resistance to Piri- Easy threshing Sh is dominant to intermediate cidaria oryzae Cav., the fungus that causes blast. or tough threshing sh; but, on the other hand, As early as 1922, resistance was reported to be tough threshing is dominant to intermediate controlled by a single dominant gene {W) - How- threshing. ever, no work has been reported on segregation of ^lultiple gene inheritance of grain length was resistance to established races. In 196Û, a labora- reported in a study in the United States {29). In tory study of three crosses was reported from crosses of short X medium, short X long, and India (7). Survival was controlled by one or medium X long types, variation in length in the two dominant genes, but the surviving plants and Fo generation Avas continuous. Similar results, the parents showed rather high degrees of also sliOAvino- trans<>:ressÍA^e seírreo;ation, Avere ob- susceptibility. tamed for breadth of grain. AAVUS are a conspicuous morphologic character. Tillering ability is of gi^eat importance Avhere Although little is known of their physiologic rice is transplanted, but much less so Avhere direct value to the plant, they are supposed to be asso- seeding at relatively high rates is practiced. ciated with general hardiness [ßO] and to offer Ramiali and Eao ('5()) reported from India that some protection against pests. Awns are objec- the Fi plants of three crosses were intermediate tionable in threshing and handling the grain. for num))er of tillers per plant, and the F2 prog- The development of awns varies considerably enies showed traiisgressive segregation. In one with environmental conditions. Varieties that cross higli correlation ))etAveen the number of show mere tip awns at moderate levels of fertility tillers 111 F2 plants and their respective F3 prog- may develop much more prominent awns at enies indicated that the controlling genes are higher levels. In Louisiana, the Caloro variety limited in mimljer—proliably no more than three develops awns when seeded very early but ma}^ be or four. In another cross the occurrence of num- practically aAvnless wlien seeded late. In the F. erous F3 progenies, each comparatiA^ely uniform generation, ratios of aAvned to awnless phiiits of in number of tillers, led to the same conclusion. 3:1, 15:1, and 9:7 have Ijeen reported from India. Standing ability or lodging resistance is a com- Japan, and the United States. These ratios show, plex cliaracter that is difficult to measure in in- respectively, tliat single, duplicate, and comple- heritance studies. In a study reported from mentary genes act to produce aAvns. A study in India {ÖO), the F2 progenies of a cross segregated California (28) shoAved that fully aAvned plants o lodging :1 nonlodging, Ijut the latter were low differed from awnle-s 'jy tAvo genes, fully aAvned tillering and late maturing. from partly aAAmed Ijy one gene, and partly aAvned In Louisiana, a cross betAveen an early-matur- from awnless l3y one gene. ing, medium-grain selection and the late-maturing Most rice A^arieties have pubescent leaves and A'ariety Eexoro indicated transgressive segrega- hulls, although a few are essentially glabrous. tion for yield (5). F4 lines Avere recoA^ered that Pubescence has Ijeen eliminated from tlie vari- had yields significantly higher than those of the eties groAvii in the Southern United States. In high-yielding parent, but none had yields sig- most varieties, a single gene pair Gl :gl controls nificantly loAver than those of the loAv-yielding the development of plaiit hairs on all outer sur- parent. Higher yield Avas strongly associated faces of the plant. However, some varieties have Avith earlier maturity. No correlation Avas found some pubescence on the leaf surface, although the betAveen yield and spikelet length and breadth, or lemma and palea are smooth. Xagao, Takahashi, betAveen yield and grain weight. and Kinoshita {1^3) reported the segregation in In correlation studies from other countries crosses of the latter type with ordinary pubescent Ramiah and Rao (5(9) indicate association of Japanese types. Three classes of pubescence plus higher yield Avith number of tillers, number of glabrous appeared in the F2 generation in ratios grains per ear, and plant height. of 9 :3 :3 :1 and 27:9 :21:3. It was concluded that Genetic information on the quality character of tAvo genes Hla and Hlb together but not singly rice is A^ery limited, although the single gene seg- bring about the deA^elopment of hairs on the leaf regation between common and Avaxy types Avas surfaces even in the presence of gl. one of the first characters studied. The inherit- .\(iK:ri I,TL UE IIAXDI'.OOK 2S9, U.S. DEPT. OF AGRIGULITJRE 14 WAXY 52 _A_ 47 28 38 49 _A_ 25 35 31 7, 24 PURPLELEAF PI Ig Ph Pr 30 _A_ 39 0.3 27 ACTIVATOR LAZY A Rd Pn la th 30 34 14 29 NECKLEAF LONG GLUME Re 25 42 BLACKLEAF INHIBITOR bl ds -Bf Ps 48 40 -A— A„ / \ 44 28 1 1 BRITTLE DWARF L-^l. doAni V di gh 46 _/^ 41 28 I GLABROUS FINE STRIPE An Ur fs Dn gl FiGiKE T).—Rice linkage .i;r(tiips aiice of aiiivlose rontent as iiidicated bv the iodine iodine value Avere much more numerous in the value was studied u\ a ei-oss of Toro hiixli iodine early-uiaturino- than in the late-maturmg group. value) ■' Texas P-^atiui (low iodine \'alue) {68). Tinkage refers to the closeness of association in The value in tlie Fi generation was low, indicat- inheritance of genes located on the same chro- ing })ai'tial (h)nnnanr'e. A hiniodal distri])ution mosomes, (xenes controlling characters that seg- was obtained in tlie FM, indicating- dominance of regate into clear-cut classes and that are viable one major ^-ene for low iodine value. An asso- are useful for determining linkage relationships. ciation was shown between low iodine \'alue and Several of the genes for color are suitable marker colored ai)iculus; the latter is also a cliaracttu' of genes. Easily classified morphologic characters the low iodine parent. RecoAcred lines with high dependent on single genes are also useful, includ- RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION ing some of the more conspicuous characters such figure 5 are based on the Japanese results. Data as awns, h)ng outer ghunes (of which recessive from other studies and reviews (¿, 23, 2^. 25, 38\ and semidominant types are known), pubescence, ()3)^ are provisionally included with the groups to neckleaf, liguleless,^ hizy (ageotropic), brittle wliich they aj^pear to l)elong. Linkages between cuhn, numerous dwarfs, waxy endosperm, and genes that ha^T been reported but not definitely viable types of chlorophyll deficiencies. h:>cated on the respective chromosomes are listed In a report from Japan^ Nagao and Takahashi in table 5. Linkages between genes that have (Jf2) presented data that established V2 linkage been reported but have not been assigned to a groups, representing, as expected, the number of linkage group are also shown in table 5. Link- chromosomes found in rice. Takahashi {63) has age maps of rice are much less complete than since amplified the information on the linkage tliose of barle}^ and maize. groups. The linkage diagrams (maps) shown in TABLE 5. LJnl'dges not defnitely located on the respective cfnowosomes Percentage Percentage Link;i.2:es tentatively Linkages tentatively recomt)ina- Authoritv recombina- Authority assiirned to groups assigned to groups tion 1 tion 1 WAXY CiKoUP LONG GLUME GROL^P— \vx vs. Pia 45 Nagao and Taka- Con. hashi iJß). Rk vs. I-An 31? Jodon (unpub- C vs. H' 29 Ramiah and Rao lished). (50). Pin vs. Re Unknown Ramiah and Rao C vs. Se 16 Chandraratna ( 10 ) [50). C vs. Lf 32 Yamagnchi {68). Re vs. Lf,? Yamaguchi {69). C vs. dp Unknown Xagamatsu and IXHIBrroK GROUP Ohrnura.i Ps vs. Psh 10 rhao {12). C vs. n_ do___.. Do.i Ps vs. Apic 9 Shafi and Aziz {59). 1 vs. do. 217? .Jodon (unpul)- Ai)ic vs. Psh 12 Do. lished). Ps vs. Pr D'Cruz (17). wx vs. X|^1- Unknown Oka (1953).! wx vs. Vi do Do.i DWAHF GROUP PUKPLE LEAF GROUP gh VS. AUß 43 Nagao and Taka- PI VS. An 29? Jodon (unpub- hashi (^2). lished ). g h VS. p or Pr_ 30 Jodon and Chilton PI vs. lop Unknown Na2:amatsu and {26). ohnnira, 1961.^ FINE STRIPE GROUP 1^ vs. Wh S Jodon {2Ji, 25). None Iff vs. Xa Unknown Nishimura.^ LAZY GROUP Pr vs. P 32? Jodon Í unpub- La vs. d Unkn(nvn Naga mat su and lished ). Ohmura.^ P vs. (blackspot)- 33? Do. Pr vs. Ig 30 Richharia and NECKLEAF GROUP others (51). nl vs. An 32? Jodon (unpub- Pr vs. Px 9 Do. lished) . Px vs. Psh C Do. GLABRO L^S GROUP Pr vs. gh 32 Jodon (24, 25). g] VS. H^ 39 Nagao and Taka- Pr vs. h 36 Do. hashi {1^2). gh. vs. Wh Unknown Do. LINKAGES NOT Ps vs. Pr ____do Hsieh {20). ASSIGNED TO d vs. PI _do_ Do. LINKAGE GROUP Pi vs. Ig _do_ Do. Rk VS. An 14 and 24 Anandan (6'). ACTIVATOR GROUP Bh vs. An 21 Kuang {S6). A VS. bn 23 Hsieh {19). Bh vs. Pin? 17 Parnell, Ranga- bn vs. doo 28 Do. swami Ayyangar, ^22 '^^''- l^t 16 Do. and Ramiah {1^1) Igt VS. bn 30 Do. An vs. d 11 Kuang {S6). A vs. doo 37 Do. Pr? vs. Pig? 13 Hebert {18). Rd vs. Pin 21 Ramiah and Rao Pr? vs. Pin 10 Do. {50). Purple collar vs. Prp 13 Breaux {9). LONG GLUME GROUP Psh vs. Prp 16 Comeaux {16). dfi vs. dT 39 Nagao and Taka- bl vs. Prp Unknown Jodon (unpub- hashi {1^2). lished ). g vs. Rk___ Kadam and D'Cruz d2i vs. Prp_ .-__do Do. {SD. sk vs. Prp__ _do__ Ramiah and Rao Apic vs. g_ 17 Do. {50). 1 As reported by Takahashi ( 6S ), 2 Entries followed by question marks have not been verified and may be changed as more information becomes available. 16 ¡Kiri I;í IRE JIANDBOOK 289, U.S. DEPT. OF AGRICULTURE ( 19 ) LI STEH, S. c. Selected References 1960. GENIC ANALYSIS IN RICE. I, COLORATION GENES AND OTHER CHARACTERS IN RICE. (1) ANON Y MOUS. Acad. Sínica Bot. Bul. 1: 117-132. 1950. WORLD CATALOGUE OK GENEIIC STOCKS RICE. (20) Food and Agr. Organ. United Nations, 30 1961. ANALYSIS OF GENES FOR BLAST DISEASE RE- pp. [Mimeographed.] SISTANCE CAUSED BY PIRICULARIA ORYZAE. Symp., studies on Cause of Low Yield 1963 RICE GENE SYMBOLIZATION AND LINKAGE of Rice in Tropical and Sub-Tropical Re- GROUPS. U.S. Agr. Res. Serv, ARS 34-28, gions, Proc. Spec. Pulx Taiwan Agr. Res. m pp. Inst. 3 : 45-52. (3) AD AIR, C. R. (21) HuTCHiNSON, J. B., RAMIAH, K., and MEMBERS OF 1934. s TIEDIE s ON BLOOMING IN RICE. AgTon. Two SPECIAL SUBCOMMITTEES. Jour. 26 : 965-973. 1938. THE DESCRIPTION OF CROP-PLANT CHARACTEES (4) AND THEIR RANGES OF VARIATION. INTRO- 1936. STUDIES ON GROWTH IN RICE. AgTOn. JOUr. DUCTION. Indian Jour. Agri. Sei. 8(5) : 28: 506-514. 567-569; ii. VARIABILITY IN RICE. 8(5): AKIMOTO, S., and TOGARI, Y. (5) 592-616. 1939. VARIETAL DIFFERENCES IN DANICLE DEVELOP- (22) ITO, H., and AKIHAMA, T. MENT OF RICE WITH REFERENCE TO EARLY OR 1962. AN APPROACH FOR THE SYMBOLIZATION OF LATE TRANSPLANTING. Crop Sci. Soc. Ja- COLORS IN RICE PLANTS AND ITS ADOPTION pan, Proc. 11(1) : 7-14. FOR THE CLASSIFICATION OF RICE VARIETIES. (6) ANANDAN. M. Jap. Jour. Breeding 12: 221-2:oo-i_oor: 1928-33. RPTS. ON AGR. STAS.. MADRAS DEPT. AGR., [In Japanese. English summary.] ADUTURIA, 1927-28 AND 1932-33. [Original not seen. Reported Itv Ramiah and Rao (23) JODON, N. E. (50).] 1948. SUMMARY OF RICE LINKAGE DATA. U.S. Dept. Agr., Bur. Plant Indus., Soils, and (7) BHAPKAR, D. G., and D'ORI^Z, R. 1960. INHERITANCE OF BLAST RESLSTANCE IN RICE. Agr. Engin., 34 pp. [Mimeographed.] Poona Agr. ( Y)l. ^lag. 51 (L>): 23-25. (24) (8) BOLLICH, C. N. 1955. PRESENT STATUS OF RICE GENETICS. Agr. 1957. INHERITANCE OF SEN'ERAL ECONOMIC (^UANTI- Assoc. China, Jour, (n.s.) 10: 5-21. TATIMÎ CHARACTERS IN RICE. I^npuhlislied (25) 1956. PRESENT STATUS OF RICE GENETICS. Agr. tliesis, PILI)., La. State Univ. (9) BREAUX, NORRIS. Assoc. China, Jour, (n.s.) 14: 69-73. 1940. CHARACTER INHERITAN(F, FA( LOR INTERAC- (26) and CHILTON, S. J. P. TION, AND LINKA(;E RELAflONS IN THE Fo OF 1946. SOME CHARACTERS INHERITED INDEPEND- A RICE CROSS. L^npublislied tliesis, Ph.D., ENTLY OF REACTION TO PHYSIOLOGIC RACES OF Dept. Of Agron., La. State Univ., 38 pp. CERCOSPORA ORYZAE IN RICE. Amor. SoC. (10) CHANDRARATNA, M. F. Agron. Jour. 38 : 864-872. 1953. A GENE FOR PHOTOPERIOD SENSITIVITY IN RICE (27) — RYKER, T. C, and CHILTON, S. J. P. LINKED WITH AiTcuLi's COLOUR. Nature 1944. INHERITANCE OF REACTION TO PHYSIOLOGIC 171 : 1162-1163. RACES OF CERCOSPORA ORY'ZAE IN RICE. (11) Amer. Soc Agron. Jour. 36: 497-507. 1955. GKNETK s OF P HoTo]'KlUODIC SENSITIVITY IN (28) JONES, J. W. RICE. Jour. Genet. 53 : 215-223. 1933. INHERITANCE OF CHARACTERS IN RICE. JOUr. (12) CHAO, L. F. Agr. Res. 47 : 771-782. 1928. LINKAGE sTn)iES IN RICE. Genetics 13 : (29) XADAIR, C. R., BEACHELL, H. M., and DAVIS, 133-169. L. L. (13) CHATTERJEE, L>. 1935. INHERITANCE OF EARLINESS OF LENGTH OF 1948. A MODIFIED KEY AND ENUMERATION OF THE KERNEL IN RICE. Amer. Soc. Agron. Jour. SPECIES OF oRYZA LINN. Indian Jour. Agr. 27: 910-921. Sei. 18(3) : 185-192. (30) JLTI.IANO, J. B., and ALDAMA, M. J. (14) 1937. MORPHOLOGY^ OF ORYZA SATIVA LINNAEUS. 1951. NOTE ON THE ORIGIN AND DISTRIBUTION OF Philippine Agr. 26 : 1-134. WILD AND CULTIVATED RICES. Indian Jour, (31) KADAM, B. S., and D'CRUZ, R. (xenet. and Plant Breeding 11(1): 18-22. 19(30. GENIC ANALYSIS IN RICE. HI. INHERITANCE (15) CHEVAL 1ER, A. OF SOME CHARACTERS IN TW'O CLUSTERED 1932. NOUVELLE CONTRIBUTION A L'ETUDE SYSTE- VARIETIES OF RICE. Indian Jour. Genet, and MATIQUE DES ORYZA. Rev. do Bot. Appl. et Plant Breeding 20 : 79-84. d'Agr. Trop. 12 : 1014-1032. (32) KATAY'AMA, TUKUDA. (16) COMEAI x, D. J. 1931. ANALYTICAL STUDIES OF TILLERING IN PADDY 1946. AN INHERITANCE AND LINKAGE STUDY OF RICE. Jour. Imp. Agr. Exp. Sta. 1(4): VIRESCENCE AND OTHER FACTORS IN RICE, 327-374. [English summary, 371-374.] ORYZA SATIVA. Uiipublished thesis, La. (33) KATO, S., KOSAKA, H., and HARA, S. State Univ., 50 pp. 1928. ON THE AFFINITY OF RICE VARIETIES AS (17 D'CRUZ R. SHOWN BY THE FERTILITY OF HYBRID PLANTS. 1960. A LINKA(;E BETWEEN TWO BASIC GENES FOR Kjusu Imp. Univ., Fakult. Terkult. Bui. ANTHOCYANIN COLOT^K IN RiCE. Sci. and Sci. Rpt. 3: 132. [In Japanese.] Cult. [India 1 25: .534-.536. ( 34 ) KOSAKA, H., and HAEA, S., and others. (18) HEBERT, L. P. 1930. ON THE AFFINITY OF THE CUILTIVATED VARI- 1938. A (iENEIlC STTn)Y OF COLOR AND CERTAIN ETIES OF RICE PLANTS, ORYZA SATIVA L. Ky- OTHER ( HARACTERs IN RICE. Unpublished ushu Imp. Univ., Dept. Agr, Jour. 2(9): thesis, La. State Univ., 57 pp. 241-276. RICE IN THE ITNITED STATES : VARIETIES AND PRODUCTION (35) KlHARA, H. lOOO. J.INKAGE STUDIES IN RICE (OKYZA SATIVA L. ). 1959. CONSIDERATIONS ON THE OKIGIN OF crLTI- Euphytica 9: 122-126. VATED RICE. Soikeii Zilio. 10: i;S-S3. ( 51! ) UODKTGO, A. (36) KuANG, IT. H. li)2, POLTJ NATION AND THE b'LOWER ol RICE. 1951. STUDIES ON RICE CYTOLO(îY AND GENETICS AS Philippine Agr. 14(3) : 155-171. WELL AS BREEDING WORK IN CHINA. AgrOIL ( 53 ) RoSCHEVlCZ, R. J. Jour. 48 : 387-397. li)31. A CONTHIBU TlON TO THE KNOWLEDGE OF RICE. (37) MATSUDA, K. P»Ul. Appl. Bot., Genet., and Plant Breed- 1929. ON THE DEVELOPMENT OF RK^E KERNELS. ing 27(4) : 1-133. [English summary, pp. Nogakii Kwaiho (Sei. Agr. Soc. [Japan] 119-133.] (54) SAKAI, K. I. Jour. ), No. 314, 34 pp. 1935. CHROMOSOME STUDIES IN ORYZA SATIVA L. (38) MATSUURA, H. I. THE SECONDARY ASSOi IATIOXN OF THE 1933. ORYZA SATIVA. His A Bibliographical Mon- MEioTic CHROMOSOMES. Jap. JouT. Gouet. ograph on Plant Genetics (Genie Analy- 11(3) : 145-156. [English summary, p. sis), 1900-1929. Ed. 2, pp. 240-265. Hok- 154.] kaido Imp. Univ., Sapporo. (00) SAMPATH, S., and GOVINDASWAMI, S. (39) MiZUSHIMA, U. 1958. WILD RICES OF ORISSA—THEIR RELATIONSHIP 1948. STL'DY ON SEXUAL AFFINITY AMONG RICE TO CI^LTIVATED VARIETéS. Rice News Teller, VARIETIES. ORYZA SATIVA L. I. ANALY'SIS OF July. AFFINITY OF .JAPANESE, AMERICAN, AND JAV- (56) and RAO, M. B. V. N. ANESE VARIETIES. Seibutu 3(2) : 41-52. 1951. INTERRELATIONSHIPS BETWEEN SPECIES IN (40) NAG AI, I. THE GENUS ORYZA. Indian Jour. Genet, and 1959. JAPÓNICA RICE. ITS BREEDING AND CULTI'RE. Plant Breeding 11: 14-17. 843 pp. Yokendo, Ltd., Tokyo. (57) and SESHU, D. V. (41) NAGAO, S. 1961. GENETICS OF PHOTOPERIOD RESPONSE IN RICE. 1951, GENIC ANALYSIS AND LINKAGE RELATION- Indian Jour. Genet, and Plant Breeding SHIP OF CHARACTERS IN RICE. In Demerec, 21: 38-42. M., ed., Adv. in Genet. 4: 181-212. (58) SEETHARAMAN, RAMASWAMY. 1959. THE INHERITANCE OF IODINE VALUE IN RICE (42) and TAKAHASHI, M. AND ITS ASSOCIATION WITH OTHER CHARAC- 1963. TRIAL CONSTRUCTION OF TWELVE LINKAGE TERS. Ph.D. Diss., La. state Univ., 65 pp. GROUPS IN JAPANESE RICE. Hokkaido Imp. ( 59 ) SHAFI, M., and Aziz. M. A. Univ., Faculty Agr. Jour. 53: 72-130. 1959. THE INHERITANCE OF ANTHOCYANTN PIG- (43) TAKAHASHI, M., and KINOSHITA, T. MENT IN THE OUTERGLUME AND APICULUS 1960. GENETICAL STI'DIES ON RICE PLANT. XXV. OF RICE. Agr. Pakistan 10: 217-232. INHERITANCE OF THREE MORPHOLOGICAL ( ( )(> ) SHASTRY, S. V. S., RAO, D. R. R., and MISRA, R. N. CHARACTERS. PUBESCENCE OF LEAVES AND 1960. PACHYTENE ANALYSIS IN ORYZA. I. CHRO- FLORAL GLUMES, AND DEFORMATION OF MOSOME MORPHOLOGY^ IN ORYZA SATIVA. In- EMPTY GLUMES. Hokkaido Imp. Univ., dian Jour. Genet, and Plant Breeding Faculty Agr. Jour. 51: 299-314. [In Eng- 20(1) : 15-21. lish.! ( 61 ) SMITH, W. D., DEFFES, J. J., BENNETT, C. H., and (44) NANDL H. K. others. 1936. THE CHROMOSOME MORPHOLOGY, SECONDARY^ 1938. EFFECT OF DATE OF HARVEST ON YIELD AND ASSOCIATION AND ORIGIN OF CI^LTIVATED RICE. MILLING QUALITY OF RICE. U.S. Dept. Agr. Jour. Genet. 33(2) : 315-336. Cir. 484, 20 pp. (45) OKA, H. I. ( 62 ) TAKAHASHI, M. 1958. INTERVARIETAL VARIATION AND CLASSIFICA- 1957. ANALYSIS ON APICULU; COLOR GENES ESSEN- TION OF CULTIVATED RICE. Indian Jour. TIAL TO ANTHOCYANIN COLORATION IN RICE. Genet, and Plant Breeding 18(2) : 79-89. Hokkaido Imp. Univ. Faculty Agr. Jour. (46) and CHANG, W. T. 50 : 266-362, 6 plates. [In English.] 1962. RICE VARIETIES INTERMEDIATE BETWEEN WILD ( 63 ) AND CUTITIVATED FORMS AND THE ORIGIN OF 1964. LINKAGE GROUPS AND GENE SCHEMES OF SOME THE JAPÓNICA TY^PE. Acad. Slulca Bot. STRIKING MORPHOLOGICAL CHARACTERS IN Bul., 3(1) : 109-131. JAPANESE RICE. 1)1 Rice Geuetics and Cy- (47) PAENELL, F. R., RANGASWAMI AYY'ANGAR, G. N., togenetics, Symp. Proc, Internatl. Rice Res. and RAMIAH, K. Inst., Los Banos, Philippines, pp. 215-236. 1917. THE INHERITANCE OF CHARACTERS IN RICE. Elsevier Pub. Co., Amsterdam, London, and L India Dept. Agr. Mem., Bot. Ser. 9: New York. 75-105. (64) TATEOK A, T. (48) RAMIAH, K., and GHOSE, R. L. M. 1963 TAXONOMIC STUDIES OF ORYZA. III. KEY^ TO 1951. ORIGIN AND DISTRIBUTION OF CULTIVATED THE SPECIES AND THEIR ENUMERATION. Bot. PLANTS OF SOUTH ASIA—RICE. Indian Jour. Mag. Tokyo 76: 165-173. Genet, and Plant Breeding 11(1): 7-13. (65) TERADA, S. (49) and NARASIMHAN, M. 1928. EMBRYOLOGICAL STI'DIES IN ORYZA SATIVA L. 1936. DEVELOPMENTAL STUDIES IN RICE. I. Madras Hokkaido Imp. Univ., Col. Agr. Jour. Agr. Jour. 24(2j : 50-66. 19(4) : 245-260. [In English.] (50) and RAO, M. B. Y. N. (66) TERAO, H., and MIDUSIMA, U. 1953. RICE BREEDING AND GENETICS. Indian Coun- 1939. SOME CONSIDERATIONS ON THE CLASSIFICA- cil Agr. Res. Sei. Monog. 19, 360 pp. TION OF ORYZA SATIVA L. INTO TWO SUB- (51) RICHHARIA, R. H., MISRO, B., BUTANY, W. T., and SPECIES SO-CALLED 'JAPÓNICA' AND 'INDICA.' SEETHAEAMAN, R. Jap. Jour. Bot. 10(3) : 213-258. 18 A(iRIOl^í/r' Jí ilAXDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE (67) TING, YING. EDGE OK THE SECOND (S.M.) LINKAGE GROUP 1041). ORIGINATION OK TllK KiCE < ' I L11V ATION IN IN RICE. Nogaku Kenkyu [Studies in CHINA. Rice Kxpt. StM., Sun Yatseii Univ., Agr. Sei.] .Tapan 13: 13.5-172. [In Jap- Canton, China. Coi. of Agr., A^^^ron. Bui. 7, anese.] Pub. series III, IS pp. [Resume in Eng- (70) YEH, B., and HENDERSON, M. T. iisli.] 1961. CYTOGENETIC RELATIONSHIPS BETWEEN CUL- (OS) YA^fAGUCHI, Y^. TIVATED RICE, ORYZA SATIVA L., AND FIVE 1921. ETUDES D'HéRéDITé SUR l^\ COUUEUß DES WILD SPECIES OF ORYZA. Crop Sci. 1: 445- GLUMES CHEZ LE RIZ. Bot. Mag. [Tokyo] 450. 35: 106-112. [English review in Internati. Rev. Sei. and Pract. Agr. [Rome] 12 : (71) YUNG, G. T. 1,399-1401.] 1938. DEVELOPMENTAL ANATOMY OF THE SEEDLING (<Î9) OF THE RICE PLANT. Bot. Gaz. 99(4) • 1929. FURTHER CONTRIBUTIONS TO THE KNOWL- 786-802. RICE BREEDING AND TESTING METHODS IN THE UNITED STATES By C. ROY ADAIR, H. M. BEACHELL, NELSON E. JODON, T. H. JOHNSTON, J. R. THYSELI^ y. E. GREEN, JR., B. D. WEBB, and J. G. ATKINS History and Objectives experiment station at each of these locations. The rice-breeding studies were started in Louisiana in Rice improvement in the United States has been 1909, in California in 1912, and in Arkansas in discussed by Jones (55),^ and the descriptions and 1931. Although a comprehensive rice-breeding performance of varieties developed have been program was not started in Texas until 1931 and reported by several authors {1,2, 25, ^í2, ^5, ^8. in Mississippi until 1958, some breeding work had 52, 57, 55, 59, 67). Although some work to im- been done in these States before these dates. prove United States rice varieties was done before Most of the early work consisted of testing 1909, it was not until about then that compre- selections from foreign introductions and com- hensive, cooperative rice-breeding studies were mercial fields. Many varieties, such as Caloro, started in the United States. Objectives of the Colusa, Fortuna, Nira, and Rexoro, were devel- rice-breeding program and methods used have oped and released from 1909 to about 1937. been described (7, 18, 55, 69), According to a S. L. Wright, r. farmer in Louisiana, developed report by the Rice Millers Association,^ all rice sevei-al rice varieties by selection. These varieties varieties grown in the United States in 1963 probably were progenies of natural hybrids be- evolved from these cooperative rice-breecling tween varieties, such as the long-grain Honduras experiments. and the short-grain Shinriki. The most widely Although introductions were made by indi- grown varieties developed by Wright were Blue viduals after the original introductions into South Rose and Early Prolific, which are medium- Carolina in the I7th century, little effort was grain types, and Edith and Lady Wright, which made by Federal or State agencies to improve are long-grain types. None of these varieties rice varieties until work was started by the U.S. were grown in 1963, but they were the leading Department of Agriculture in 1899. At that time varieties in the southern rice area from about Seaman A. Knapp, an explorer in the Division of 1915 to 1940. Botany, introclucecl from Japan 10 tons of Kiushu rice that Avas distributed in southwestern Louisi- During the early years, no attempt was made ana and probably in eastern Texas, where he ar- to improve varieties by hybridization. Although ranged farm demonstrations of rice varieties and a few hybrids had been made at experiment sta- cultural methods. Many varieties were intro- tions in the southern rice area at an earlier elate, duced and tested by Department workers on it was not until after 1922 that this method of demonstration farms in Louisiana and Texas, and breeding was used. later in Arkansas and California, before the es- The primary objective in rice breeding in the tablishment of rice experiment stations in these United States is to develop varieties that will States. assure a maximum and stable production of the The Rice Experimental Station at Crowley, types of rice required by producers and con- La., was established in 1909. The Biggs Rice sumers. Emphasis is given to developing short- Field Station at Biggs, Calif., (now the Rice season varieties. Short-, medium-, and long-grain Experiment Station) and the Rice Experiment types—with a wide maturity range within each Station at Beaumont, Tex., (now the Rice-Pas- grain type class—should be developed. The ob- ture Research and Extension Center) were estab- jectives of that program are to develop varieties lished in 1912. The Rice Branch Experiment that (1) germinate quickly and grow rapidly in Station at Stuttgart, Ark., was established in the seedling stage; (2) tolerate low temperature 1926. Rice investigations were started at the in the germinating, seedling, and flowering stages Delta Branch Experiment Station, Stoneville, and tolerate low irrigation water temperatures Miss., about 1951. Rice-breecling investigations during the entire growing season; (3) are re- are conducted cooperatively by the U.S. Depart- sistant to alkaline and saline soils and to salt in ment of Apiculture and the State a2:ricultural the irrigation water; (4) are resistant to diseases and insects; (5) have short, stiff straw and resist ^ Italic numbers in parentheses refer to Selected Ref- erences, p. 62. lodging; (6) respond to and make efficient use of 2 Shown printed in Rice Jour. 66(12) : 14-15. 1963. maximum rates of fertilizer; (7) mature uni- 19 20 A(íiaCUI/rUKE IIAXDIÎUOK 1289, U.S. DEPT. OF AGRICULTURE formly ami produce seed that has a period of al)ly rapid drainage when necessary. Howe\-er dormancy so that the o-raiii will not (jerminate the slope should l)e sucli that blocks of tliree- when ]Kir\est is dehiyed by i-ain; (S) produce tenth aci'e or larger can be uniformly irrigated maximum held and milling yields when grown without contour levees. under a wide range of environmental conditions: In the Taiited States it is customarj- to locate and (9) have the desired cooking and processing roadways at 200- to 300-foot intervals running in ([ualities required by domestic and foreign trade. the directiim of the fall of the land and wide Each of tliese objectives is important in earli enough to acconnnodate held equipment and other rice-producing area in the T'nited States, altliough vehicles. The road ditches are used for drainage some of the olijectives are more important in one and are paralleled by border levees. The entire area than in another. For example, cold toler- area should be graded to a uniform slo])e before ance, esjiecially tolerance to cold irrigation water, roadways and irrigation laterals are constructed. is more important in California than in the south- Cross levees at designated points divide the field ern rice area. Disease resistance, on the other into areas of approximately one-tenth acre that hand, is more important in the southern rice area than in California. can be irrigated or drained independently (fig. 6). Larger blocks can be formed by eliminating one Cultural Methods and Equipment or more cross levees. Irrigation laterals parallel for Breeding Rice in the United States roadways and are located midwa}' between the roadwaj'S or directly adjacent to one side of the Land for rice-breeding experiments should be roadways. of uniform soil type and topography. A gradual Ricefield machinery is used to build levees. In and uniform slope is desirable to afford reason- heavy clay soils, a steel-bladed levee builder (fig.. tvim^MtKi»«ai-'-«ÊÊinim .1 FiGUKE 6.—Seeded nursery plots. Some of the plots are irrigated. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 21 Texas. It consists of 1 year of rice followed by 2 years of summer fallow. The first summer after rice is grown and harvested, the field is fallowed and then clover or ryegrass is sown in the fall. The crop is harvested for hay or seed in the spring, and the field is sunnner-fallowed through- out the second summer. Land is leveled during the second summer as time and weather permit. On clay soils the cross levees are reconstructed in the late fall or winter before the fields are seeded again with rice. After cross levees are construi'ted, the land is prepared by using lift- type implements attached to a lightweight farm tractor. On silt loam soils the cross levees may be made inunediately after seeding. In California, a 2-year rotation generallj' is usecl in rice-breeding nurseries. The land is plowed in the winter or early spring after the rice crop has been grown and harvested. The fields usually are irrigated one or more times dur- ing the summer when they are not cropped to rice to germinate weed, grass, and rice seeds. The field is cultivated after each irrigation to destroy the plants that emerge. FIGURE -Constructiug levees in the nursery with Permanent levees are maintained in some of steel-bhided levee builder. the areas used for rice nurseries. In other areas, plastic levees are used, or earthen levees are con- 7) is used; in the nioi-e loamy soils, a disk-type structed with a bulldozer or front-end loading levee builder (fig. 8) is used. Usually the cross tractor each year before seeding. levees have an S- to Id-foot base. A concrete Weeds and grass are controlled on lateral and levee packer is useful in packing newly con- drainage ditch banks, levees, and alleyways in rice structed levees. A concrete tile, -Í to G inches in by spraying with a contact herbicide. diameter, is placed at the lower end of each block Various types of seeding equipment are used. to drain the water into the road ditch so that it will hold the irrigation water. The tile is closed with a metal plate. Sometimes plastic tube siphons are usecl to irrigate from the lateral or to drain the water into the road ditch. In the southern rice area, it is customary to plow down the cross levees after each rice crop and to cultivate the fields with ricefield equip- ment. The irrigation laterals and border levees may or may not be torn dowji. After cross levees have been i^lowed down, the areas are disked or plowed ancl are leveled with a land plane. A 3- year rotation system is practiced in Arkansas and Louisiana. In Arkansas, the land may be cropped to soybeans the first year. The soybeans may be harvested or turned under or disked into the ground as green manure, after which a winter grain crop may be sown. The grain crop may be overplanted with lespedeza the following spring. The grain crop is harvested in early sunmier, and the lespedeza is harvested for hay or seed in the summer or fall. The field is plowed or disked, and land is leveled during the winter and early spring preparatory to seeding rice the following year. In Louisiana, the land is fallowed when not in rice. FIGURE 8.—Constructing levees in the nur.sery with a A 3-year rotation system is also practiced in- disk-type levee builder. 22 AGRICULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE In field plot varietal experiments, seeds are sown with small grain drills or specially equipped drills. In yield trials on nursery plots or in experiments where multiple seed sources are in- volved, belt-type seeders (fig. 9) or other readily cleaned drills are used for seeding. Breeding nurseries involving numerous panicle-row selec- tions are sown by dribbling seed into a single- row manually operated drill (fig. 10) or a multi- ple-row power-operated drill. On experimental plots uniform application of known amounts of fertilizer materials is difficult. A basal application of phosphorus and potassium may be applied with a conventional fertilizer dis- tributor before seeding rice or to one of the other crops groAvn in rotation with rice. Although the fertilizer usually is distributed by a tractor- drawn implement, it may be distributed by air- plane. In the southern rice area, the nitrogen fertilizer for breeding trials usually is applied as a topdressing, although sometimes part or all is applied at seeding time. Various methods and devices have been used to apply fertilizer to rice grown in breeding nurseries. Weighed amounts of fertilizer are applied by hand as a topdressing. Mechanized fertilizer distributors have been tried with only limited success. Most devices are slower than hand application, do not apply or distribute uni- form amounts of fertilizer, and can be used only ;i*í¿5íyi^^':--íí«í on relatively dry soil. At Stuttgart, Ark., a manually operated FrouBE 10.—Manually operated seeder used to seed "planter" is used to apply nitrogen fertilizer be- selections. tween alternate rows when the soil is dry (fig. 11). At Crowley, La., a single-row seeder that has an agitator-type fertilizer attachment with a sep- arate shoe places fertilizer just below the seed. For a number of years a fertilizer distributor attached to a 3-row seeder was used at Beaumont, Tex. This drill used regular grain drill fertilizer distributor parts. Top-feed and other hopper- type distributors have been used with limited suc- cess to topdress plots. A force-feed type dis- tributor that drops the fertilizer on the soil sur- face is fairly successful (fig. 12). Cross-plot fer- tilizing with this type distributor appears to be desirable in overcoming irregularities of distri- bution. Because rice nurseries are likely to be muddy at harvesttime, mechanical han^esting equipment is not used. Hand sickles are used to harvest small plots; combine harvesters may be used to harvest large plots. Bundles from small plots are air dried by hang- r^:^.r ing in a drying shed or by using heated-air driers. When dried by heated air, the bundles are placed FIGURE 9.—Belt seedt-r, mounted on a small tractor, used in drying trays as harvested and dried over a tun- for seeding nursery yield experiments. nel or rack-type drying unit with forced heated RICE IN TUE UNITED STATES : VARIETIES AND PRODUCTION 23 <»•• ï-<*i,*.i«.. : ;«*•«*««( FiGUKE 12.—A force-feed fertilizer used to distribute nitrogen as a topdressing. FIGURE 11.—A distributor used to apply nitrogen ferti- Maintenance of viable seed of varieties and lizer between the rows as a topdressing. breeding lines is important in a rice-breeding program. The main causes of rapid deterioi-a- air (fig. 13). Bundles are left in the trays until tion of seed viability are moisture content of the the grain is ready to be threshed. seed and storage temperature. A method of dry- Bundles from large plots are threshed in a ing the seed and storage facilities with low hu- Vogel thresher (fig. 14) or a modified Kansas- midity and low temperatures are needed. type nursery thresher (fig. 15). Sometimes the The moisture content of the grain is probably concave teeth are removed to reduce breakage. more important than temperature in retaining Threshing rice is primarily a stripping action, viability. Bice with a moisture content of 10 and breakage is avoided when concave teeth are percent or below (wet basis) retained viability not used and cylinder speed is reduced. Break- for several years at Beaumont, Tex. The tem- age caused by improper adjustment of the perature in the storage room ranged from 70° to thresher should be avoided because it causes a 90° F., and the relative humidity was below 50 bias of grain yield and milling quality. percent most of the time. In some instances, bundles are placed on the cross levees for a few hours after cutting and are The moisture content of rough rice can be re- threshed the same day. The threshed grain is duced to 4.7 percent (wet basis) when stored 42 placed in cloth bags and artifically dried with days over a saturated solution of lithium chloride forced air heated to between 90° and 100° F. {60). The moisture content of rice can be re- Threshed samples usually are cleaned before duced to about 6 percent with a silica gel drying weighing for yield determinations. It may also unit (fig. 16). Rice reduced to this moisture be necessary to break off awns and attached frag- content probably will retain viability for 5 years ments of rachises. This is accomplished by plac- or longer when stored at room temperatures. ing the sample in a section of automobile inner- At Beaumont, Tex., seed of rice varieties, breed- tube and pounding several times. An easily ing lines, and genetic stocks is dried in a silica cleaned aspirator, dockage machine, or small fan- gel drier to about 6-percent moisture and stored ning machine can be used to remove foreign ma- with silica gel in sealed 1.2-cubic foot metal con- terial. If the threshed samples are relatively free tainers at about 34° F. About 2 pounds of silica from foreign material, the grain weight can be gel is put in each container. An indicator, such obtained before cleaning. as cobalt chloride crystals or paper, that changes AGRICULTURE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE 24 FiGL-KK 13.—ln-yiug bundles of rice in trays with forced ¡leated aii'. FiGURK 14.—Thresliing breeder seed with a Vogel thresher. color with increase in moisture is used, so that an increase in moisture is easily detected. The silica According to Jones (öß), few varieties were gel is usually chang-ed every 2 years. Seed can be stored in polyethylene bags with silica gel. How- introduced from about 1G85 to 188'.). It became ever, since these bags do not exclude all the evident then that the varieties being grown m moisture, the silica gel must be changed more the United States were not as productive as varieties grown in other countries. Starting frequenth. At Crowley. La., and Beltsville. Md.. seed is about 1800 and continuing to the present, many stored at a temj)erature of about 0"' F. Seed varieties have been introduced. Jones (on) listed stored in this manner has retained its viability and described nine varieties that were intro- for more tiian -20 years. duced from other countries and grown in the Ignited States. These were Carolina Gold, Caro- Breeding Methods lina White. Early Wataribune. Hcmduras, Km- shu. Omachi, Onsen, Shinriki. and Wataribune. The three major breeding methods commonly About 193,5, Asalii was introduced from Japan by used foi' small grain have been used in rire T. M. Sabora, a Texas rice farmer. He increased breeding (■'i''). These are (1) introduction of this \-ariety for commercial production al)out varieties from foreign countries, (-2) selection (if mill {'>7).' Tlius, there have been at least 10 pure lines from ciunmercial and introduced varie- introduced \arieties that have been grown rather ties, and (3) creation of new varieties by hybridi- extensively. None of these varieties are now of zation followed liy selection. Irradiation breed- commercial importance. ing also has been used in the United States. Varieties now introduced into the United States The varieties now grown in the United States are grown the ñrst year in a greenhouse away were developed liy using progressively the thi'ee from rice production centers to avoid the intro- major methods. For e.xample. the (iulfrose vari- duction of diseases and insects. The seed pro- ety was selected from the i)rogeiiy of a cross duced in the greenhouse then is sown in a single- between a selection from an introduced variety row plot at one of the rice experiment stations. and a pure line selection from a commercial Notes are taken on such characters as seedling variety. \igor, straw strength, plant height, length of growing season, grain type, kernel characters, Introduction and reaction to diseases and insects. Whether The introduction of varieties from other coun- the variety is a pure line or consists of mechanical ti-ies has been and still is an important source of or hybrid mixtures is also noted. Varieties that germ plasm for rice breeders in the United States. appear to have no desirable characters are dis- Some of the introduced varieties have been de- carded. Varieties that have some but not all veloped by Ijreeders in the country of origin, and desirable characters are held in reserve for pos- others have been indigenous varieties grown for sible future use in the breeding program. Varie- manv years by farmers in the country of origin. ties that look promising in all respects in the RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 25 FIGURE 15.—Threshing bundles of rice from nursery yield FiGURE 16.—Silica gel drying apparatus for drying small experiment with a modified Kansas nursery thresher. samples of rice. fully observed for the principal characters. If a preliminary trials are tested for at least 3 years selection from the progeny of a hybrid is segre- in replicated yield trials and are evaluated ior gating, desirable plants or panicles are selected disease reaction and cooking quality. AVlien a and sown in single-row plots the second year. variety is proved to be superior to commercial AVhen promising lines are breeding true to type, varieties, the seed is purified and increased and they are tested in replicated yield trials in the seed of the new variety is distributed to farmers. same manner as introductions. When a selection is proved to be outstanding, it is named, the seed Selection supply is purified and increased, and it is released Selections from introduced or commercial vari- for commeivial production. eties have been an important source of rice varie- ]Most of the varieties developed by the selection ties in this country. Practically all of the method have been replaced by newer varieties, varieties grown in the United States from 1920 although there are a few notable exceptions. Li to about 1945 were developed by this method. 19().3. Bluebonnet ."lU was the leading variety in Jones {ôô} named the breeders who partici- the South, and Rexoro was grown rather widely pated in this work from about 19U0 to about 1930. in Louisiana and Texas. Caloro was the leading Most of these breeders were employees of the U.S. variety in California, and Colusa also was widely Department of Agriculture. Chambliss and grown in that State. Jenkins (25) listed and described six varieties Hybridization that were developed by selection. These are Acadia, Delitus, Evangelhie, Salvo, Tokalon, and Varieties developed by the selection method Vintula. These six varieties were not grown ex- were a A'ast improvement over the varieties they tensively but probably were important for a few replaced, but varieties developed by this method years in local areas in Louisiana. Ten other var- did not have all the desired characters. Since ieties developed by selection and listed and briefly about 1922 rice breeders in the LTnited States described by Jones (-'T-5) are Blue Rose, Caloro, have used the hybridization method of rice breed- Colusa, Early Prolific, Edith, Fortuna, Lady ing, and hundreds of crosses have been made. Wright, Xira, Rexoro, and Shoemed. Other Three S3'stems are followed in the hybridization varieties developed by pure line selection are Con- method of breeding rice. These are: (1) Two way (29), Sunbonnet (4^), Bluebonnet 50 (-57), varieties are crossed and the progeny grown in and lola. Latex, Mortgage Lifter, Storm Proof, pedigreed rows or bulk plots until pure lines are and Zenith (58). Other selections have been selected; (2) the backcrossing system in which made by farmers and grown locally for a few two varieties are crossed and the Fi plants crossed years. to one of these varieties and repeated for four Selection is a relatively easy method for breed- or five times; and (3) the multiple cro.ssing sys- ing rice, but it takes many years to develop a tem in which four or eight varieties are crossed variety by this method. The procedure is to in pairs, followed by crossing the Fi plants from select a large number of plants or panicles from the different combinations so that after two or a variety that consists of diverse types. These three rounds of crossing, Fi plants are obtained selections are sown in single-row plots and care- that contain some genes from each of the parent HANDBOOK 289, U.S. DEPT. OF AGPaCULTLlKE 26 A'liKlJ varieties, These systems iiiny O be modiñed in that day or the next day, pollen from a male A'^arious ways. panicle that has many florets just starting to CROSSING TECHNIQUES.—Tlie two basic tech- bloom is dusted on the stigmas of the emasculated niques used for making rice crosses are the clip- panicle. Before pollination the bottom of the ping- and the liot Avater method. There are sev- inverted bag on the emasculated panicle is slit so eral modifications of the clipping method but in that it can be spread open and can serve more or each case a part of the lemma and palea is re- less as a funnel while the pollen is being applied. moved. In the hot water method the panicle is The bag then can be closed, folded over, and emersed in hot water. fastened with a paper clip. The pollinated pani- An example of the clipping technique that has cle is then tagged to show the designation of the been widely used was described by Jones {55) and parents and the date of pollination. may be summarized as follows : In the morning As a result of the elevated temperature within before the rice begins to bloom, or in the after- the bag, seed set may be poor in crosses made by noon after the daily blooming period has passed, clipping the floret. In an effort to devise a tech- all except 10 to 20 spikelets are removed from the nique for making a cross that would not require female panicle. The upper part of the lemma and bagging the female panicles, Jodon {39\ devel- palea of the remaining spikelets are clipped off at oped the hot-water method for emasculating rice about a 45° angle. This removes about half of flowers. In this method, the female panicle is the lemma but only the tip or none of the palea immersed in water at a temperature of 40° to so the anthers can be easily removed with fine- 44° C. for 10 minutes in the morning before any pointed forceps. The emasculated panicle then of the florets have opened. This critical tem- is tagged and covered with a glassine bag. The perature renders the pollen grains ineffective but same day or the next day between 9 :00 a.m. and does not prevent the normal functioning of the 2:00 p.m., depending somewhat upon the weather, female portion of the rice florets. Within a few the emasculated panicles are pollinated. Phmts minutes after the panicle is removed from the of the variety to be used as the male parent are warm Avater, the florets that w^ould have bloomed examined, and a panicle that has spikelets about later that day open. These florets can be pol- to bloom is taken. A spikelet that has the linated in the same manner as in the clipping anthers pushing up toward the tip of the floret method. Spikelets that already have been pol- is opened, and an anther or two are placed in the linated and spikelets that do not open are clipped emasculated flower. Usually the anthers are off. Spikelets at the base of the panicle usually broken open and the pollen is dusted on the are immature and can be left to produce mother stigma. This process is repeated until all flowers seed. It may not be necessary to bag the panicle, have been pollinated. After pollination, the pani- because the lemma and palea usually close in cle is again enclosed in the bag and the designa- about 45 minutes. Thus, they usually are closed tion of the parents and the date of pollination before other plants start to shed pollen. The pol- are written on the tag. linated panicle then is tagged to show the desig- A modification of the clipping method has been nation of the parents and the date of pollination. used at the Eice-Pasture Research and Extension SINGLE CROSSES.—The crossed seeds are planted Center, Beaumont, Tex. In this method, the tips in a greenhouse in the fall after the cross is made of the lemma and palea are clipped off at right or in the field the next spring. AVlien the Fi angles to the longitudinal axis of the spikelet. plants are grown in the greenhouse during the The anthers then are removed by vaccum, Ijy winter, a year is saved because the F2 population means of a fine glass nozzle connected to a vac- can be grown in the field the year after the cross uum jnunp that is driven by an eleotric motor is made. operating from a storage battery. Emasculating Usually several Fi plants are grown to assure is done in the early morning or in the late after- that typical parental strains were used in making noon; and pollinating, bagging, and tagging are the crosses. The cross should be made so that the completed in the same mainier as in the clipping Fi plant can be distinguished from the female method described by Jones {55). parent variety. For example, when pubescent X Another techniciue that has been used for cross- nonpubescent varieties are crossed, the nonpube- ing rice is a modification of a method developed scent variety should be used as the female parent. for wheat and barley {85). In this method, the Fi plants should be propagated vegetatively until lemma and palea are^clipped at right angles to the it is known that they are not needed for addi- longitudinal axis of the spikelet at a point just tional seed production or other purposes. Vegeta- above the tip of the stigma. This cuts the an- tive propagation of Fi plants is also helpñil in thers, and it is not necessary to remove them. obtaining increased quantities of F2 seeds. The florets are clipped early in the morning or in Seeds from the Fi plants are spaced thinly or the afternoon, and then the emasculated panicle space sown in rows 12 inches or farther apart. is covered with a fairly large glassine bag. Later When space sowai, seeds are placed 3 to 6 inches RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 27 apart in the row, so the F2 plants can be examined from each panicle is seldom sufficient for seeding mdividually for plant characters and disease at more than one or two locations. Small samples reaction. A further advantage of space seeding for quality tests and a few seeds for disease F2 populations is that all the seed produced by a nurseries may be obtained by bulking part of the selected F2 plant can be harvested and used for seed from each of the 6 to 15 panicles harvested (1) preliminary quality tests on milled samples from a given F3 line. The remaining panicles in (5 to 10 grams), (2) growing at different loca- a line may be harvested in bulk to provide addi- tions or dates of seeding to obtain information tional seed for testing the line for resistance to on reaction to diseases and to photoperiod and straighthead, hoja blanca, and blast; and for other environmental influences, and (3) seedling seedling hardiness, grain quality, or other char- tests in greenhouse or growth chamber for blast acters. The F4 lines are handled in much the reaction and seedling hardiness. In important same manner as the F3 lines. Usually from 3 to crosses where known genetic variables can be 6 selected panicles of each line are sown in identified, early-generation testing has proved panicle-row plots the following year. very effective. Early-generation testing is continued until it The rice-breeding procedures used in the F3 is reasonably certain that the lines are no longer and subsequent generations usually are governed segregating for the characters under study. by particular circumstances such as available per- From 10 to 15 panicles are selected from non- sonnel, physical facilities, financial considera- segregating rows, and then the rows are harvested tions, urgency of a particular development, and threshed in bulk. Part of the seed from the number of characters involved, and mode of harvested rows is used for more extensive labora- inheritance. tory grain quality tests. The pedigree system has been more widely used Lines that have suitable grain type are then than other systems of handling hybrid progenies, tested in a preliminary yield trial. Some lines although modifications of the pedigree and bulk may be discarded because of lack of vigor, weak systems are frequently followed. straw, disease susceptibility, undesirable cooking In the pedigree system, the F2 plants are care- quality, or other undesirable characters. Lines fully examined in the field and laboratory. The that are heterozygous for one or more characters selections that appear to be satisfactory for all but otherwise appear to be desirable are replaced characters studied are sown in individual rows by pedigree sublines selected from later genera- (8 to 16 feet long and 12 inches apart) the tion panicle rows. True breeding lines usually next spring. Seeds are spaced thinly in rows. can be isolated in six to eight generations. The Space seeding is seldom used for F3 and later true breeding lines then are tested for at least 3 generations. years to determine yielding ability, disease resist- "ÍYlien facilities and circumstances permit, a ance, time of maturity, plant height, stiffness of system of multiple screening of selections may be straw, and cold tolerance, and to check thoroughly used. Desirable plants are saved from the Fo milling, processing, cooking, and other characters. progenies in the field, and each i)lant is threshed Lines that prove to be superior to existing varie- individually. A small portion of the grain of ties in one or more characters are then named, the each is milled, and plants having chalky kernels seed is purified and increased, and the seed of the are discarded. Milled samples from the remain- new variety is distributed to growers. ing plants are tested in the laboratory to deter- The bulk sj^stem has been used to a limited mine cooking quality. Undesirable plants are extent, particularly where time and space were eliminated, and the seeds of each of those remain- limiting factors. True breeding lines usually ing after the double screening are divided into can be obtained in fewer generations when the three parts. One part (about 25 seeds) of each pedigree method is used. is tested for reaction to hoja blanca under con- In the bulk system of breeding, the Fi plants trolled conditions. Another part is seeded late in are grown and the F2 populations are sown in the the field under conditions believed to be favorable same manner as in the pedigree method. The F2 for the development of blast. The third part is population is harvested and threshed in bulk. seeded in the breeding nursery to observe agro- Progenies from each cross may be kept separate nomic characters and to proAdde seed for further or the progenies from several crosses with similar testing of lines surviving the multiple screening. parentage may be combined. From 10 to 25 rod This screening method eliminates many undesir- roAvs are grown in F3. They are harvested and able lines in the F3 generation. threshed in bulk and sown on a similar size plot The F3 lines are carefully examined through- the next year. This procedure is followed for out the growing season and usually from 6 to 15 each succeeding generation until Fe or F7. In panicles are selected from lines that have the bulk-hybrid populations, special care should be desired plant and grain type and that appear to taken to be sure that desirable plant types are not be resistant to diseases. The quantity of seed teing eliminated through natural selection. For 28 ■ K LV' :i: HANDBOOK 289, U.S. DEPT. OF AGRK ULTURE example, tall and profiise-i illeiiiia' tv})es tend to I{-I), Rexark, R-N, Saturn, Texas Patna, Toro, eliminate shoi*t types (6"). TP 4Í), and Vegold. Many of these varieties were The bulk system often is modiñed in various not in commercial production in 1963, although ways. For example, if there is a diíí'erential \'arieties developed from crosses comprised about plant reaction to a natural or artifically induced S5 ¡percent of the United States acreage that year. infection of a serious disease, a bulk is made up BACKCKOSS.—The Ijackcross system or a modifi- by selecting the resistant plants. Plants that cation of the typical backcross system is success- make up the bulk are sometimes tested for proc- fully used to some extent in rice breeding in the essing and cooking quality. Where the parents United States. As w^th other small grains, this differ in grain type, panicles having the desired system LS used when it is desired to transfer one grain types are selected in bulk or the Indked ^^^w^ or a small number of genes to a fairly well- seed is graded on the basis of length and width, adapted variety. This system has not been used and the desired grain type is saved. This opera- as widely with rice as with other small grains. tion might be repeated foi* seA'eral generations. Commercial rice production methods in the AAHien unfaAV)ra))le v\'eather or a shortage of helj) United States have undergone periodic changes makes selections in the field impossible, a com- (combine harvesting, increased fertilizer use, new posite may be harvested and panicles selected in herbicides) that have resulted in rather drastic the laboratory. In tliis case, the grain from changes in plant-type requirements. Because rice selected plants is combined for seeding the bulk breeders have had to search for divergent types, plot the next year. the use of standard varieties as recurrent parents In California, progenies from each cross are in a formal backcross ¡program has been pre- sometimes grown in small, water-seeded plots vented. As production methods become more where the material is seeded under conditions stable and satisfactory plant types are developed, similar to those of tlie commercial ricefields. and as rice breeding progresses in the United This method aids the l)reeder in selecting plants States, the backcross method may be used more that emerge readily through deep water. Also, generally. Adair, Miller, and Beachell (7) de- when rice is water seeded, some varieties do not scribed briefly the development of hoja blanca develop sufficient roots, and plants may tend to resistant, long-grain types by backcrossing. lean as the grain matures. Thus, when rice is Calrose {ñ7), a medium-grain variety, was de- water seeded in l)reeding studies, plants may be \'eloped by this method of breeding. evaluated for resistance to this type of lodging. MULTIPLE CROSS.—IMultiple crossing has been Each year the material may be subjected to used very^ little by rice breeders in the United natural selection pressures in an attempt to elimi- States. Several varieties have been developed nate undesirable types. Examples of luitural from rather complex crosses, but none of these selection pressures are: Harvesting I)efore late were selected from a population obtained from plants are mature if short-season types are de- systematically crossing four or more varieties. sired; seeding uiider conditions where straight- head is likely to occur; or inoculating with Irradiation Aphelerichohles hessey¡ Christie (sometimes called Irradiation breeding has been employed in the A. orijzae Yokoo) to eliminate plants susceptible United States. Several mutants that niay be use- to white tip. After six or seven crenerations, a ful m breeding programs have been obtained in large number of plants or panicles' are selected, this manner, but no varieties have been developed. preferably from a space-planted population. The plants are carefully examined and only those that appear to have strong straw, disease resistance, Breeding for Agronomic Characters and good grain type are selected. Seeds of the Rice often is seeded early in the spring when selections are then examiiied in the laboratory the soil temperature is low,^r it may be sown in much the same as seeds from Fo plants are ex- water that is below the optimum temperature. ammed, and those that appear to liave the desired Ihus, seedling vigor is an important character kernel characters are sown in single-row plots the of rice varieties, and it is desirable to studv seed- next year. The selections are then handled in the ling vigor and cold tolerance concurrently \and to same manner as advanced-generation selections obtained by the pedigree method. cond)ine the two characters in a rice variety. Many rice varieties have been developed in the At optimum temperatures, indica varieties gen- I lilted States by the livl)ridizatio]i method. Va- erally grov^ faster in the seedling stage than do rieties rhat were named and rele;ised are as fol- japónica varieties. However, some of the japón- h)ws: Arkrose, Belle Patna, Bluebonnet, Caladv ica varieties are more tolerant to low tempera- Century Patna 2:]1, Cody, Delrex, Gulfrose, Im- tures, and seedlings of these cold-tolerant janonica proved P>]uebonnet, Kami'ose, Lacrosse, Ma^niolia varieties may grow and develop faster than seed- Missouri R-500, Nato, Xortlirose, Nova, Prelude^ lings of mdica varieties when the temperature of the soil or water is low. RICE IN THE UNITED STATES : VAPvIETIES AND PRODUCTION 29 Vigor and cold tolerance of seedlings are inmiediately thereafter. When blooming occurred studied under controlled conditions {68) and in during periods of cloudy weather and moderate the ñeld. In the controlled studies, the seeds are temperatures, practically all lines showed good sown in water and the temperature is maintained seed sets. When temperatures were higli and at 60° F. The length of longest leaf at about 'M) humidity was low, practically all lines showed days is the criterion used to judge tolerance and poor seed sets. After several years, the test was vigor. The varieties aiid lines that are vigorous abandoned because it required a great amount of and cold tolerant under controlled conditions are time and efl'ort and provided little information. tested in the fieUl. P^ield experiments are con- Varieties that produce maximum yields must ducted by water seeding in ñelds where the irriga- have relatively short and sturdy straw, so that the tion water is cold, or by drill seeding early in the rice does not lodge before harvest (fig. 17). spring. Because variability is high under field Japónica varieties have smaller and shorter culms conditions, results for a particular experiment are and shorter, narrower, and darker green leaves not always dependable. But over a period of than do most indica varieties. Although there years, useful information can be obtained on the are exceptions, japónica varieties generally pro- performance of varieties under these adverse duce higher yields than do indica varieties; this conditions. indicates that morphologic characters might be Varieties also diifer in their response to low associated with grain yield. The japónica varie- temperatures during the flowering stage. This ties have tough but willowy stems. The less character of rice varieties and breeding lines is willowy straw character of the indica varieties is studied by seeding late, so that pollen develop- preferred since this type is less likely to lodge. ment and flowering occur when the temperatures For several years, rice breeders have been are low. In Texas, when temperatures are below searching for plants with short, slender stems; the optimum in October when rice is flowering, with erect, relatively narrow, dark-green leaves hardy varieties, such as Caloro, continue to de- of intermediate length; and with low percentages velop; whereas cold-sensitive varieties, such as of sterility at high rates of nitrogen fertilization. Bluebonnet 50 and Century Patna 231, may not Strains approaching this description have been produce seed. selected from crosses between a Taiwan variety, Eice varieties also vary in response to high Tainan-iku Xo. 487 (P.I. 215,936),^ and United concentration of salts in the irrigation water and States varieties. Ten short-stature selections from in the soil. Varietal response to salt was studied these crosses were grown in a variety-fertilizer at Stuttgart, Ark., and Beaumont, Tex. At test in 1961. They averaged 4,224 pounds of Stuttgart, on soils with a high salt content. Ark- rough rice per acre at the 160-pouncl nitrogen rose produced 4,180 pounds per acre and Blue- rate and 3,367 pounds at the 80-pound rate. The bonnet 50 produced 3,172 pounds. On soils with highest yielding strain yielded 5,658 pounds at lower concentration of salts, Arkrose produced the 160-pound rate and 4,022 pounds at the 80- 4,531 pounds per acre and Bluebonnet 50 pro- pound rate, compared with Bluebonnet 50, an duced 3,838 pounds. At Beaumont, with a con- indica type variety, which yielded 3,448 and centration of sodium chloride of about 2,500 parts per million in the irrigation water. Caloro produced 1,789 pounds of grain per acre, whereas Toro produced only 842 pounds. "N^Hien no salt was added to the irrigation water, Caloro pro- duced 4,820 pounds per acre ancl Toro 3,716 pounds. •*->*/'■ The Beaumont studies were conducted in 1/10- acre blocks of Beaumont clay soil. Approxi- mately 2,500 parts per million of salt was main- tained in the irrigation water by adding sodium chloride. Frequent additions of salt were needed because of dilution from rains and soil moisture exchange. As much as 15,000 pounds of salt per acre was used during the 70- to 80-day test. Salt was first added to the irrigation water when the rice plants were about 45 days old. Under these conditions an attempt w^as made to grow breeding lines in single-panicle rows as well FIGURE 17.—A field of Caloro rice showing serious lodging. as to conduct yield tests in replicated nursery 3 P.I. refers to the accession number assigned to foreign plots. Widely different responses occurred be- introductions by the Crops Research Division, Agricultural cause of weather conditions during blooming and Research Service, U.S. Department of Agriculture. 30 AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICUijTURE 2,916 pounds, respecti\'ely, at tlie two rates of The cause of the increased sterility was not de- nitrogen fertilization. termined. This promising dwarf type will be In an eti'ort to find short-stature types possess- studied further. ing superior yielding capacity, varieties that com- üenerally a high rate of nitrogen fertilizer is bine extremely narrow and erect leaves and small applied to rice-breeding nurseries to select tyjDes stems have been crossed. that respond to fertilizer and that resist lodging. Short-strawed plants have been found in hybrid When pure lines are isolated, they are then tested and irradiated populations, as mutations from at two rates of nitrogen fertilization. Usually a varieties, and in introductions from foreign coun- I'andomized, split-plot design is used with varie- tries. In Arkansas, naturally occurring dwarf ties as the main plots and with nitrogen rates as types were saved from C.I. 9187,'' a high-yielding, subplots (fig. 18). lodging-resistant, early long-grain experimental At Stuttgart, Ark., a continuing experiment variety that has short straw and narrow leaves. designed cooperatively by the agronomist, the Crosses were made with Eluebonnet types to im- plant breeder, and the plant pathologist has been prove milling quality, and dwarf and semidwarf established to compare outstanding experimental types were saved for testing. varieties with commercial varieties they might be The short-stature types showed considerable expected to replace. Varieties are tested in ma- variation in plant height because of the degree of turity groups and receive nitrogen fertilizer at a internode elongation. Club and grassy dwarfs number of rates and times. The varieties are seldom grow more than 12 to 18 inches tall. Since checked closely for grain yields and disease reac- grains are shortened and fretjuently are otherwise tion, lodging, and other characters in the field. distorted, they are of no economic value. Some Milling yields and chalkiness of the grain and intermediate-height, dwarf-type lines exhibit kernels resulting from the various treatments are varying degrees of grain distortion. Other inter- also checked. To deA'elop a satisfactory nitrogen mediate-height, dwarf-type lines appear to pro- fertilization program for each variety'^so that it duce grains of normal size and shape. will give consistently high grain yields with a All of the dwarf-type plants examined ap- minimum of lodging and disease," possible new peared to have the normal number of nodes. The varieties are tested 2 or 3 years as part of a final reduced height was governed by the extent of evaluation before their release. internode elongation, including the peduncle (in- In fertilizer-variety tests at Stuttgart, Ark., ternode just below panicle). In all but one C.I. 9434, a very short-season, experimental long- dwarf-type selections examined, all internodes of the stem, including the peduncle, showed reduced elongation when compared with normal height .V"-, plants. An exception to this elongation pattern was observed in a dwarf plant selected at Beau- mont, Tex., iii 1955, from an irradiated popula- tion of Century Patna 231. The panicles of this selection were normal in length and floret num- ber, and the peduncles were of about normal length. The lower internodes showed only minor elongation; this resulted in an extremely short and sturdy plant. The grains of the dwarf were of normal length but appeared to be slightly tapered. This dwarf was crossed with normal Bluebonnet 50, Century ,.-. m Patna 231, Rexoro, and Texas Patna. Dwarf- m^ type selections resembling the original strain were recovered in about a 3 normal :1 dwarf-type ratio m all crosses. The original and the dwarf-type selections from the crosses were tested in yield expermients and invariably showed about 15- to 20-percent lower yields thkn did normal strains. All the dwarf-type strains showed considerably more sterility than did the normal strains, which was probably responsible for the reduced yields. ^ C.I refers to the accession number used in the Cereal Cops Research Branch, Crops Research Division Agri- ViGXTRK 18.—C.I. 9446 fertilized at two rates: Left, 200 eumn-al Research Service. U.S. Department of AgHcûi- pounds of nitrogen per acre produced a yield of 5,707 pounds of rice per acre; right, 40 pounds of nitrogen per acre produced 3,942 pounds of rice per acre. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 31 grain variety, produced 5,992 pounds of grain per gram. Although early and very early types have acre compared with 5,839 pounds produced by gained favor in recent years, a complete range of Bluebonnet 50. In both tests the treatment in- maturity types is maintained. chided 200 pounds of nitrogen per acre, but C.l. Partial dormancy in rice is desirable, so that 9434 produced this relatively high grain yield in rice does not germinate if rain and humid weather 45 days less time than did Bluebonnet 50; and occurs at harvesttime or if plants are badly the straw of C.I. 9434 was 14 inches shorter. lodged. -Seed of nondormant varieties will germi- The resvdts from these experiments indicate nate before cutting if there is a prolonged period that it will be possible to develop short-strawed, of rain after the grain is ripe. It sometimes is nonlodging varieties that respond to high rates of desirable to break dormancy of seeds soon after fertilizer. Notes on breeding lines and strains in harvest. This is necessary in the case of crossed yield tests recorded about 30 and 60 days after seeds to be planted in the greenhouse in the winter seeding and at maturity provide valuable infor- or otlier breeding material to be grown during the mation on plant type. By using symbols, brief off season in another region. This can be done notes are obtained on (1) habit of growth of by treating in a 0.10- to 0.05-percent solution of leaves (erect to spreading) ; (2) color of leaves sodium hypochlorite for 24 hours or by heating (light to dark green) ; (3) leaf width (narrow to in shallow, open containers for 3 to 5 days at 47° wide) ; (4) plant or seedling height (short to to 50° C. ^ tall) ; and (5) degree of tillering (low to high). Rice varieties in the United States are divided Calculating sterility percentage by counting the by grain size and shape into three types. These number of sterile and fertile florets on selected are short- (Pearl), medium-, and long-grain panicles of breeding lines appears to have merit. types. The more slender, long-grain varieties are The grain yield of breeding lines and experi- sometimes considered as a fourth type. Examples mental varieties is determined by using replicated of each type are Caloro, Nato, Bluebonnet 50, and nursery plots. For comparison, standard varie- Rexoro, respectively. The grain type can be ties are included in each trial. The experimental visually classified; but for more critical compari- design is a complete randomized block, usually sons of varieties and for classification, more exact with four replications. The plots are about 1 rod measurements are needed. At the Cooperative (5 meters) long and three or four rows wide, Rice Quality Laboratory at Beaumont, Tex., the usually the rows are spaced 9 inches apart in the various grain types are characterized objectively 4-row plot or 12 inches apart in the 3-row plot. according to length, width, length/width ratio, The plots are trimmed to a uniform length before thickness, and grain weight« Dimensions of harvesting. For yield determination, the center rough (paddy), brown, and milled (head) rice row is harvested in the 3-row plot, and the two grains are measured and reported in accordance interior rows are harvested in the 4-row plot. with tlie following definitions: One or both of the border rows may be harvested (1) Length of awnless rough rice is the in order to have a larger sample for milling and straight-line distance (millimeter) from the point cooking tests. of disarticulation of the grain, which is below the An alternate method is the use of 4-row plots outer glumes, to the tip of the apiculus (fig. 19, usually 15 or 16 feet long with a 12-incli spacing B). For awned rough rice the tip of the lemma between rows. An 8-foot segment from the two is the reference point. Length for brown and center rows is harvested. By careful harvesting, milled rice is the distance between the most dis- the remainder of the plot is left standing for later tant tips of the kernel, including the embryo of observations and for collection of panicle samples. the brown rice kernel (fig. 19, A). In California, where the rice on all farm fields (2) Width (dorsiventral diameter) for rough is sown broadcast in the water, the method used rice is the distance (millimeter) across the lemma for testing varieties is somewhat different. The and palea at the widest point (fig. 19^ B). Width rice is sown in the water by hand. for brown and milled rice is the distance across The design used for preliminary trials is a com- the kernel at the widest point (fig. 19, x4). plete randomized block with three or four repli- (3) Thickness (lateral diameter) for rough cations. The individual plots are a single row, rice is the distance (millimeter) from one out- 12 to 16 feet long, with the rows spaced about 24 side surface of the lemma to its opposite at the inches apart. The preliminary trial gives infor- thickest point (fig. 19, />). Thickness for brown mation on the ability of the variety to emerge and milled rice is the distance from one side of through the water, straw strength, and other the kernel to its opposite side at the thickest characters. The best varieties then are tested in point (fig. 19,6^). randomized, quadruplicated plots large enough to By modifying a photographic enlarger, a device be harvested with a small combine. was built for measuring the length and width of Time of maturity (length of growing season) rice (fig. 20). The enlarger was mounted on a is an important consideration in the breeding pro- box with three sides that were painted black on 32 AGKICUI/rUIUÍ HANDBOOK 289, U.S. DEFT. OF AGRICULTURE FIGURE 20.—Device for mea.suring rice grains and kernels. The light source was a 6- or 12-volt cold, sealed- beam, automobile spotlight. The spotlight had a smooth surface, so that light or shaded areas would not be projected on the grid. Any cold light source of similar intensity should be satisfactory. A 50-mm.F/4.5 liminized lens was used. This lens made it possible for the enlarged image (lOX) to be projected on a grid that was less than 24 inches from the lens. A glass slide that held 10 grains was placed in the light field just above the bellows and the 50- millimeter lens. A millimeter scale was placed on the glass slide. The image of the millimeter scale was magnified 10 times and made possible accurate focusing before use. The adjustable bellows to which the 50-millimeter lens was at- tached made it possible to obtain a clear-cut image. The enlarged images of the rice grain were measured to obtain the length and width. The thickness of the rice grain was determined by using a micrometer caliper graduated in milli- meters. The micrometer was placed in a small vice attached to a table. A sheet-metal tray at FIGURE ]».—Points from which rice grain and kernel lueasiirenient .should be inarle. the base of the micrometer, to catch grains dropped during the operation, is useful. If similar equipment is not available, a random the inside. A black cloth was placed over tlie sample of 10 grains or kernels can be placed open side of the box to exclude most of the li<;ht, adjacent on transparent tape in the desired posi- so that a distinct image of the rice grain would tion for the particular measurement, and the total appear on the white grid. Minute adjustments length, width, or thickness can be measured with were made to obtain a magnification of exactly a fair degree of accuracy by using a transparent 10 times. ruler. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 33 The length, width, and thickness of milled Milling Quality kernels are determined by measuring 15 whole kernels selected at random from a representative The objective of rice milling is the removal of sample. The coefficient of variation for each hulls, bran, and germ with a minimum breakage dimension is calculated for each of 15 kernels to of the endosperm. The milling process generally determine the uniformity, of size and shape. Size consists of four fundamental operations: (1) and shape classes for brown kernels are as Cleanino' the field-run rouirh rice to remove sucli follows : thnigs as mud lumps, rice stems and leaves, weed seeds and stems, and other foreign matter; Leïigth (2) shelling the cleaned rice to remove the hulls; Size classiricatio)i {MiUunetejs) (3) scouring the brown rice to remove the coarse Extra long (EL) Over 7.5 outer layers of bran, white inner-bran, aleurone Long (L) 6.61 to 7.5 layers, and germ; and (4) gi^ading the mixture Medium (M) 5.51 to 6.6 of Avhole and broken milled kernels according to Short (S) Up to 5.5 size classes known as head rice (whole-grain milled kernels), second head (larger pieces of Lengthy Shape classiticatio)i icidth ratio broken milled kernels), screenings (smaller pieces of broken milled kernels), and brewers rice (very Slender Over 3 Medium 2.1 to 3 small pieces of broken milled kernels) (7, 16). Bold Up to 2.1 In modern rice mills, all operations in the rice- milling process are performed mechanically with a minimum amount of manual labor, including The average length, length/width ratio, thick- the transfer of rice from one machine to another ness, and 100-grain weight of rough, brown, and for the next series of operations. Fraps (-5Ö), milled (head) rice for each of 18 varieties are Geddes {31, pp, 2043-2051)^ Kik and Williams tabulated in table 6. (62), Wayne (5-^), and, more recently, Kester {61) have described the commercial milling of Testing for Milling, Cooking, rice as practiced in the United States. Additional and Processing Qualities information describing rice milling and proc- essing equipment has been published by the Food The determination of milling, cooking, and and Agriculture Organization of the United Na- processing qualities of hybrid progenies, breeding tions (9. ¿4). lines, and new varieties is an essential part of the The milling quality of rice is based on the yield rice-breeding program. New varieties that are of head rice obtained, since it is usually the milled released for commercial production must meet product of the greatest monetary value. Yields established standards for these qualities. Certain of head rice vary widel}^, depending on variety, cooking and processing qualities are historically grain type, cultural methods and other environ- associated with specific grain types. For ex- mental factors, and the drying, storing, and mill- amiole, most of the long-grain varieties grown in ing conditions. The yield of total milled kernels the United States cook dry and flaky, and some (head rice and all sizes of broken kernels) is im- are used for specific processed products. The portant, too, and this yield is influenced by the short- and medium-grain A^arieties grown in the proportion of hulls and the amount of fine par- United States are more moist Avhen cooked than ticles of broken kernels unavoidably included in are the long-grain varieties and are used for spe- the bran fraction during the milling process. cific processed products such as dry cereals. Thus, In rice-breeding programs, rigid laboratory it is desirable that a new variety have the same milling tests are required to insure that any new cooking and processing qualities as the variety it variety released will consistently produce high replaces. vields of head rice and total milled rice. At the 34 71)1'.<>ÔK 28 y, U.S. DEPT. OF AííRIOUÍ/rURE TABLE 6.^—(rníin .'luc; . / ,s for IS rice ra riet ¡es grown in Unifomi Yield Nurseries in Arkansas and Texa^iy 1959-61 [Values are averages and are for first cutting only] Grain characters Grain type and variety Grain form ^ 100-grain Length Ratio Thickness L/W weight Millimeters MilUnieters Grams Short-grain : Í Rough 7.3 2.0:1 2,3 2.8 Caloro -- I P>ro\vn_^ 5.4 1.7:1 2.1 2.3 I Milled- 4.9 1.8:1 2.0 2.2 ÍRough- 7.1 1.9:1 2.5 2.8 Cody Brown. 5.4 1.7:1 2.1 2.3 [Milled. 5.0 1.7:1 2.0 2.2 ÍRough 7.2 1.9:1 2.3 2.8 Colusa Brown. 5.4 1.7:1 2.0 2.3 Ulilled. 5.0 1.8:1 1.9 2.2 Medium grain : ÍRough. 8.4 2.6:1 2.2 3.1 Arkrose Brown. 6.3 2.3:1 1.9 2.4 |Milled_ 5.8 2.2:1 1.8 2.2 fRough_ 7.8 2.4:1 2.1 2.5 Cal rose _ ¡Bi-own. 5.9 2.2:1 1.8 2.0 (Milled. 5.6 2.3:1 1.8 1.9 Ruugh. 8.0 2.5:1 2.0 2.5 Gulfrose •Brown 6.3 2.3:1 1.8 2.0 (Milled. 5.8 2.3:1 1.7 1.9 ÍRough. 8.3 2.5:1 2.1 2.6 Magnolia . ■Brown 6.3 2.3:1 1.8 2.1 (Milled._ 5.9 2.3:1 1.7 2.0 ÍRougli 7.3 2.4:1 2.0 2.1 Nato ■ Brown _ 5.8 2 2*1 1.7 1.7 I Milled. 5.3 2 2 '1 1.6 1.6 ÍRough.. 7.7 2.4:1 2.1 2.4 Northrose (Brown. 5.8 2.1:1 1.9 1.9 I Milled-. 5.4 2.2 :1 1.7 1.8 f Rough. 7.8 2.4:1 2.0 2.3 Zenith ¡ Brown. 6.0 2.3:1 1.7 1.8 I Milled- 5.7 2.3:1 Long-grain : 1.6 1.7 Rough.. 8.7 3.7:1 1.8 2.1 Belle Patna Brown.. 6.8 3.4:1 1.7 1.7 Milled- 6.5 3.4:1 1.6 1.6 Rough 9.6 3.8:1 1.9 2.5 Bluebonnet 50 Thrown 7.2 3.4:1 1.7 2.0 Milled.^ 6.8 3.4:1 1.6 ÍRough-- 1.8 9.1 3.9:1 1.8 Century Patna 231 •Brown-. 2.1 7.0 3.4:1 1.6 1.6 I Milled-. 6.5 3.4:1 1.6 1.5 ÍRough-, 8.8 Rexoro 3.9:1 1.7 2.1 ■ Brown-_ 7.1 3.6:1 iMilled. 1.6 1.7 6.5 3.5:1 1.5 1.5 ÍRough.. 8.9 Sunbonnet 3.6:1 2.0 2.4 Brown.- 7.2 3.3:1 (Milled- 1.8 1.9 6.7 3.3 :1 1.6 1.8 I Rough.. 9.1 Texas Patna _ 4.0:1 1.7 2.0 Brown.. 7.1 3.6:1 IMilled— 1.5 1.6 6.6 3.6:1 1.5 1.5 ÍRough.. 9.0 3.8:1 Toro ¡Brown. 1.9 2.2 7.1 3.4:1 1.7 1.7 [Milled. 6.5 3.3:1 Í Rough- 1.5 1.6 TP 49 9.4 4.0:1 1.8 2.2 j Brown,. 7.3 3.7:1 IMilled- . 1.6 1.8 6.7 3.6:1 1.6 1.7 1 Rough = unhulled grain: brown = bran, and germ removed. irain with hull removed; milled = whole grain milled kernels with hull, RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 35 Cooperative Rice Quality Laboratory at Beau- A method also is available for milling very mont, Tex., three methocls are available for esti- small samples of rice (76). This method can be mating the milling quality of rice varieties and used to mill the rice from one panicle. The rough selections. The method used depends on the rice sample is thoroughly cleaned and hulled in a amount of rice available for testing. The official McGill sheller, and a ö-gram sample is weighed grading method for determining the milling qual- for milling. The weighed sample is put into a ity of rough rice bv United States standards, test tulje witli 3 grams of abrasive (40- to 60-mesh described by Smith {78, 79, 80. 81) and adapted fused white aluminum oxide or clean, sharp, to laboratory conditions, gives the breeder com- white quartz sand). The stoppered test tube is parative information regarding milling quality of mounted in the test-tube miller, which holds 80 the more advanced selections grown in larger test tubes, and is shaken for 45 minutes at a speed plots. The method requires 1,000 grams of rough of approximately 390 strokes per minute. The rice for each determination. samples then are remo^Td and polished in a small A modification of the official method requires sample polishing machine (77). This method of only a 125-grani sample {19) to estimate the milling small samples not only gives information milling quality of rice and enables the breeder to on the milling quality of individual plant selec- check milling cpuility at very early stages of selec- tions but also provides a milled sample to use for tion. The samples of rough rice are sealed in preliminary tests of the physical and chemical glass jars and kept at room temperature for at properties of the kernel. least 24: hours to bring the moisture content to The average milling yields of hull, bran, total, equilibrium before the rice is milled. The mois- and head milled kernels for each of 18 varieties ture content is determined, a 125-gram sample of grown in the Uniform Yield Nurseries in Ar- the rice is hulled in a ÄIcGill sheller, and the kansas, Louisiana, and Texas from 1958 through brown rice is weighed. The weight of the hulls 1961 are tabulated in table 7. Estimated yields is determined by subtracting the weight of the were determined according to the modified pro- brown rice from the weight of the rough rice. cedure of Beachell and Halick (19). The brown rice sample is milled in a small McGill miller for 30 seconds, using a 14-pound Cooking and Processing Qualities weight over a steel j)late that covers the rice. The Rice varieties differ gi^atly in cooking and sample is immediately milled a second time for processing qualities. Among the domestic varie- 30 seconds, using a 4-pound weight. This second ties the quality of home-cooked rice has been milling gives a high polish to the rice kernels but described as varying from very sticky to flaky causes little additional breakage. The milled ker- (46)' Fully cooked grains of typical United nels are sealed in a glass jar to prevent unneces- States short- and medium-grain varieties are sary breaking due to rapid or uneven cooling. usually somewhat sticky, relatively firm, and tend The bran is screened through a 20 X 20 mesh wire to stick together. Typical long-grain varieties screen to recover the small, broken kernels that usually cook to a flaky state with a minimum of passed through the miller screen. The finely splitting and do not tend to stick together. Other broken kernels thus recovered are aspirated and terms used to subjectively describe cooking qual- added to the milled kernels. The milled kernels ity are moist or clry, soft or firm, and mealy or are weighed when the rice has cooled to room che^v;\^ Since different cultural groups prefer temperature. The weight of the bran and polish different textures, there is a rather widespread de- is the difference between the weight of brown mand for all types for use as home-cooked table rice and the weight of total milled rice. rice. The whole kernels are separated from the total There is also a demand for all types of rice for milled portion with a sizing device developed by use in the widely different prepared products. the Grain Division, Consumer and Marketing Processors of rice prefer different textures for Service, U.S. Department of Agriculture. This their various products and also specific qualities device makes use of two indented plates, with flat- adapted to the processes themselves. According bottom holes, tilted at a slight angle and shaken to Kester (61)^ a substantial amount of the do- by an eccentric mechanism. During the shaking mestic rice crop is processed into various kinds of motion, the rice travels the length of the top prepared foods such as parboiled rice, quick-cook- sloping plate and drops onto the bottom sloping ing rice, breakfast cereals, canned rice, canned plate. A^Hiole kernels drop off the end into a soups, canned rice and vegetable mixtures, dry container; broken kernels fall into the indents in soup mixes, enriched baby foods, and frozen the plates. Plates with specific size indents are dishes. Rice flour is used in various processes, used for each grain type. Results usually are and broken rice is often used in brewing. Typical reported as percentage of hulls, bran, head rice, long-grain varieties are preferred for many par- and total milled kernels. boiled and quick-cooking products, and specific 'M'> .X1)F,( )OK 2 8*J, I .8. DEPT. OF AíílíICULTUKE TABLE 7.—MilliiKj ///./rZ/v fo)' 18 riee vro-ietics (frown in Uniform Yield Nurseries^ /n A/'/]'((nrsa.s^ Loui^^ianiu (ind Te.rru^^ 1958-61 I Values are avei-a^res and are for first cutting only] Milling yields ^ Grain type and variety Milled rice Head rice Hulls Bran Total average average average Average Range Pere ent Pereent Percent Percent Percent Short-grain : Caloro 18 73 68 58-72 Cody 19 67 58-71 Colusa 18 65 42-75 Medium-grain : Arkrose 20 71 63 33-70 Calrose 19 10 71 69 63-72 Gulfrose 20 10 70 65 58-70 Magnolia 20 9 71 m 63-72 Nato 19 9 72 68 63-73 North rose 20 12 68 64 59-69 Zenith 20 10 70 64 53-71 Long-grain : Belle Patna 19 11 70 60 50-69 Bluebonnet 50 19 11 70 63 52-68 Century Patna 281 21 12 67 62 Rexoro^ 50-67 19 13 68 52 36-61 Sunbonnet 19 10 71 62 Texas Patna- 50-71 19 13 68 58 48^65 Toro 19 10 71 TP 492 67 60-70 19 11 70 58 52-62 1 Total milled rice is the head rice and all sizes of broken kernels. Head rice is the whole grain milled kernels 2 Grown only in Louisiana and Texas. long-ofrain varieties are preferred for certain Some of the chemical and physical tests are the canned soup products. Medium- and slu)rt-o;rain determination of amylose content (57), starch- varieties are more suitable for dry breakfast iodine-blue value {3%)^ gelatinization tempera- cereals and for use in baby foods and'in brewin^r. ture {S3), type and extent of disintegration of The short-grain types exclusively are used for whole milled kernels in contact with dilute alkali makinfi puffed rice. {65), and amylograph pasting qualities {33). Ahhouirh in the Uiuted States each o-rain type The amylose content of rice, particularly of is generally associated with specihc crmking and long-grain types, has recently been associated processing qualities, notable varietal exceptions with cooking quality (77,57). The investigations withm each grain type have been reported; and of Williams and others {87) showed that the the nontypical cooking and processing quality of long-gi^am domestic varieties known to cook dry- these grain-type exceptions in relation to nieas- ñaky usually had the highest amylose content; ured differences in some chemical and physical whereas the^ amylose cont^ents of tlie short- and qualities of the rice grain has been discussed {2(K medium-grain varieties investigated were some- what lower. The glutinous (w^axy) varieties con- Tn rice-breeding pi'ograms, cooking and i)roc- tain virtually no amylose. The simple, rapid, and essmg quality is considered to be an important measure of the suitability of a variety or selection somewhat empirical starch-iodine-blue test {31^) IS particularly useful in breeding programs for tov specihc purposes. At the Cooperative Rice estimating the relative amvlose content of early- Quality Laboratory at Beaumont, Tex., results of generation breeding material. specihc chemical and physical tests collectively serve as indices of cooking and processing qual- The gelatinization temperature of rice is be- ities Ihe results guide the rice breeder in select- lieved to be closely related to cooking quality. ing lines that combine the desired cookino- and Ihe amylograph studies {33) showed that most processing qualities and agronomic features^ The short- and medium-grain varieties gelatinized at merit of this type of evaluation has been clearly lower temperatures than did most of the long- demonstrated. * gram varieties investigated. These results were conhrmed by granule swelling and birefringence RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 37 end-point temperature (BEPT) determinations characters of the short- and medium-grain varie- ties listed in table 8 are a relatively low amylose The reaction of milled rice kernels in contact content, a relatively low gelatinization tempera- with dilute alkali has been used to classify the ture, a very pronounced alkali reaction, and M cooking quality of rice {66^ 83). The type and relatively low viscosity of the cooked paste wdier extent of disintegration of whole milled rice ker- cooled to 50° C. The typical long-grain varieties nels in contact with dilute alkali were reported are qualified by a relatively high amylose con- more recently {65). Two distinct reactions w^ere tent, an intermediate gelatinization temperature, noted: (1) Spreading where the kernels disinte- a slight-to-moderate alkali reaction, and a maxi- grated into small granules and spreading to sev- mum increase in viscosity of the cooked paste eral times the origmal kernel size; and (2) clear- when cooled to 50° C. Of the typical long-grain ing where the starch is solubilized with a loss of types, the late-maturing varieties Rexoro, Texas opacity. Spreading and clearing were evaluated Patna, and TP 49 consistently had the highest on a numerical scale from 1 (minimum) to 7 amylose content, the lowest peak viscosity, and a (maximum). A slight-to-moderate reaction was maximum viscosity of the cooked paste W'hen characteristic of most domestic long-grain varie- cooled to 50° C. These varieties are preferred ties and a more pronounced reaction w^as charac- for certain canned souj) products. The non- teristic of most short- and medium-grain varieties. typical cooking and processing quality of Century A very high correlation between tlie alkali reac- Patna 231 and Toro, both long-grain varieties, has tion and gelatinization temperatures has been been discussed previously. observed {SS). Physical and chemical grain quality evaluation The pasting quality of several domestic varie- tests are invaluable to the plant breeder in de- ties as determined w^ith the amylograph have been veloping varieties with specific processing and described {33). In general, amylograph curves cooking quality. The specific tests used depend of rice varieties were typical of those of other on the quality variables of the particular hybrid cereal starches, but they showed appreciable dif- population in question and the purpose for which ferences among the varieties studied. Long-grain the end product is to be used. varieties with the highest amylose content usuallj^ The results of the starch-iodine-blue and the showed the greatest increases in viscositj^ when alkali digestion tests enable the plant breeder to cooled to 50° C. Amylograms of most short- and classify early-generation hybrid lines as to gela- medium-grain varieties generally exhibited rela- tinization temperature of starch and relative tively shorter gelatinization times. amount of amylose. Promising advanced-genera- Notable varietal exceptions within each grain tion lines are evaluated from data obtained in type were observed by Halick and Kelly {33). analytical tests for amylose and protein content, For example, the long-grain varieties Rexark and pasting qualities using an amylograph, and cook- Toro had amylose contents, gelatinization tem- ing, parboiling, and canning tests. In certain peratures, and alkali spreading and clearing reac- crosses where it is essential to retain a specific tions similar to those of typical short- and pasting quality or parboiling and canning char- medium-grain varieties. These long-grain varie- acter, it may be necessary to obtain amylograph ties are also thought to resemble the typical short- data on early-generation lines to make certain and medium-grain varieties more in cooking qual- that the desired qualities are recovered. Such ity than thej^ do other long-grain varieties. Of tests are usually conducted on a relatively small all the varieties tested, Century Patna 231, a long- number of samples because of the quantities of grain variety, and Early Prolific, a medium-grain grain required and the time used in performing variety, had the highest gelatinization tempera- the tests. Parboiling and canning tests using 5 ture and were the most resistant to the action of to 10 grams of rough rice can be conducted on dilute alkali. Tti general, these varieties have not rather large numbers of samples if necessary, but been widely accepted for certain types of cooked the cost is relatively high. rice and processed products. The cross Gulfrose X Bluebonnet 50 is an ex- Average values for some of the physical and ample of how quality tests aid in the rice-breeding chemical characters of 18 rice varieties grown in program. In this cross, the objective was to the Uniform Yield Nurseries in Arkansas, Louisi- develop a long-grain Bluebonnet 50 type possess- ana, and Texas, from 1958 through 1961, are ing the hoja blanca resistance of Gulfrose. Gulf- tabulated in table 8. Environmental and other rose ordinarily shows a low gelatinization tem- factors influence these qualities to some extent; perature and relatively low amylose content, however, within a limited range, the values are whereas Bluebonnet 50 ordinarily shows inter- representative of each variety. In the rice-breed- mediate gelatinization temperature and relatively ing program, characters of new selections are al- high amylose content. ways compared with comparably grown commer- A large number of long-grain types resem- cial varieties. Some of the physical and chemical bling Bluebonnet 50 were saved from the F2 plant 38 .SJDBOOK 2 8 9, I.S. DEFr. OF AíjKICULTURE TABLE S.—Physical cuui rnnnicaJ characters of ¡nilled kernels for 18 rice varieties grovni in Uniform Yichi Xurscries in Ar/i'an^as, Loiii^siana. and Texas^ 1958-61 [Values are for fírst cuttin.s: only] Physical character Chemical characters (paste viscosity ) ^ Grain type and variety Gela tin i- Alkali reaction 3 Am y lose zation Cooled to Peak content - tempera- 50° C. ture 2 Spreading Clearing Bidboider Brtihrndcr Units Units Perçoit ° C. Short-grain : Caloro 850 690 19 00 7 6 (^ody 950 090 17 07 6 6 Colusa --- 840 090 18 07 6 5 Medium-grain : Arkrose __ _ - 820 000 21 04 7 6 ('airóse 900 080 19 05 7 6 (iulfrose 750 000 19 66 6 5 ^la^^nolia 920 700 14 07 6 5 Nato -- 900 040 10 67 6 5 Northrose 820 030 15 07 6 0 Zenith 800 710 19 00 6 5 Long-grain : Belle Patna 820 770 20 70 4 2 P>luelj()nnet 50 _^ 790 730 24 73 4 2 Century Patna 231 î)50 730 10 77 o 1 Rexoro 000 750 28 09 4 3 Sunbormet 810 740 20 73 4 2 Texas Patna 03O 7(]0 28 71 4 3 Toro 870 740 17 05 7 6 TP 49 090 770 28 09 4 3 1 Average LTniform Yield Nursery in Texas, 1958-61. 2 uniform Yield Nurseries grown only in Arkansas and Texas. 3 Reaction in 2.0 percent potassium hydroxide S( dut ion. population. A portion of the grain from each the United States on the reaction of rice varieties plant saved was milled in a test-tube miller. The to the various rice diseases and on developing milled samples were visually examined for grain resistant varieties. Much of this work has been texture, size, and shape; and alkali digestion and reviewed (Í5, 14). The symptoms, control meas- iodine-blue values were determined. Samples ures, and importance of the rice diseases occur- showing grains of intermediate gelatinization ring in the United States are given in the section temperature and relatively high amylose (an '^Rice Diseases,'' ]). 118. Methods used to breed iodine-blue value of 25 or below) were saved for resistant varieties are presented in this section. hoja blanca testing. In the F3 plant generation, Certain basic principles apply to breeding for a bulk made up of 15 or more panicles was again disease-resistant varieties of a crop. Techniques milled, and the quality tests were repeated. The to create an epiphytotic of the disease and to strains that appeared satisfactory agronomically evaluate and record the response of the plant to after F5 or F^ plant generations were increased the causal organism must be developed. Then the for yield testing; and at this stage other quality available varieties and breeding lines must be tests for characters, such as analytical amylose tested to determine sources of resistance to the and protein content and pasting viscosity, were causal org-anism. ^ Resistant varieties can then be made. crossed with varieties possessing other desirable characters, the progenies can be tested, and the resistant lines can be isolated. A^Hiere a resistant Breeding for Disease Resistance variety has few attributes other than resistance to the disease under study, it may be used as the The easiest, most i)ra('tiral, and least expensive donor variety in a backcross program. In order way to control rice diseases is to use resistant to develop efficient breeding techniques, the mode of inheritance of reaction to causal organisms varieties. Considerable research has been done in must be determined. RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 39 Blast of blast but do not appear promising for develop- Blast, caused by the fungus Pirwiilaria oryzae ing an improved commercial variety are crossed Cav., is an important disease of rice. Much re- with a suitable variety or strains. Testing for search has been done on it in the United States reaction to blast is then repeated. This operation and in other rice-producing countries. Physio- may be repeated several times, or until suitable logical races of P, oryzae that occur in the United plant types occur. States (6'4) make the breeding of resistant varie- Many breeding lines have been tested, and ties more complex than if races did not occur. promising strains of all grain types have been de- (renes for resistance to eacli race that is known to veloped to combine resistance to several of the occur in the United States are available, but not more connnon races of blast found in the United all are present in any one variety. States. In Arkansas, in greenhouse tests. Nova A satisfactory method for inoculating plants was resistant or moderately resistant to most of (5) and a system of rating reaction have been the races of blast. In field tests, it was con- developed (64). Many varieties in the World siderably more resistant than was Nato. Nova Collection and breeding lines have been tested was released in 1963 jointly by the Crops Re- under controlled conditions for reaction to specific search Division, Agricultural Research Service, races of F. oryzae. Uniform trials have been con- U.S. Department of Agriculture, and the Arkan- ducted in the field under a wide range of en- sas Agricultural Experiment Station (4^). vironmental conditions {13), Some studies on Brown Leaf Spot the genetics of reaction to P. oryzae have been made (IS. 66)^ but information is not available on Brown leaf spot, caused by the fungus Helmin- the genetics of reaction to all races. thosjyorhim- oryzae B. de Haan, is a common An accelerated program of testing and breeding disease of rice in humid areas. In 1941 a report rice for resistance to blast in the United States was published (4) concerning the mode of inherit- was started in 1959. The initial tests consisted ance of resistance to Hehninthospormm in a cross largely of screening in the greenhouse the more of a moderately resistant and a susceptible vari- promising varieties and selections for reaction to ety. Inoculation with conidia was used to induce races 1 and 6. Later, many other breeding lines infection. All gradation from moderately resist- from Arkansas, Louisiana, and Texas rice experi- ant to susceptible occurred in the segregating pop- ment stations were screened. Material grown in ulations. This indicated that the reaction was the field and harvested in the late summer or controlled bv several o-enes lackino- dominance. early fall is available for greenhouse testing from The reaction of seedlings grown in the green- Xovember through March. house showed a fairly close relationship with that The method used for developing blast-resistant varieties in the LTnited States {13) is as follows: of mature plants grown in the field and suggested (1) Seeds from F3 or F4 progenies of crosses the possibility of early elimination of a large pro- between varieties possessing the desired resistance portion of susceptible segregates in breeding for genes are saved. resistance (J^.). (2) Seedlings from these progenies are inocu- According to Nagai [66)^ he and Hara studied lated in the greenhouse to determine reaction to an especially susceptible mutant, and susceptibil- race 6. Susceptible selections are not tested ity proved to be due to a single recessive gene in further. crosses of a very susceptible and a normal plant. A breeding program to develop varieties resist- (3) Seedlings that are resistant to race 6 are ant to brown leaf spot was begun at Beaumont, then inoculated, in the greenhouse with race 1. Tex., about 1938. C.I. 9515, a resistant but (4) Selections that carry resistance to races 1 agronomically undesirable strain selected from a and 6 are sown in the field for further evaluation cross made at Beaumont in 1938, was crossed with of field and gi^ain characters. Many of the less popular long-grain commercial varieties in 1945. desirable lines are eliminated at this stage. Resistant selections from the 1945 crosses were (5) Seedlings of the selected lines are inocu- crossed to commercial long-grain varieties in lated in the greenhouse with races 1 and 6 to con- 1959. Selecting for resistance was started in the firm results of previous tests. F3 population by saving the more resistant plants (6) Selections that are resistant to races 1 and in rows showing the best resistance, along with 6 then are inoculated with races 2 or 4, 7, 8, 16, other desirable quality. A highly susceptible and 19, as time and facilities permit. spreader variety was sown adjacent to each selec- (7) Selections that are resistant to all races are tion. Differences in disease reaction were relative then grown in the field in observation rows or in and were more apparent between panicle rows yield tests for further evaluation as potential than among individual plants. Resistance was new rice varieties. based on the number and size of spots. The Selections that are resistant to the desired races studies indicated that inheritance is not simple NDBOOK 2 8'J, U.S. DEPT. OF AGRICULTURE 40 HA and probably involves seveinl o-eiies. Selecting considered as new varieties, none were released. for resistance was continued tlirough several gen- Belle Patna, from a diflFerent cross, was re- erations or until apparent true breeding lines leased as a new variety in 1961 {23), This Avere established. Resistant lines possessing good variety has Bluebonnet as its source of straight- agronomic characters were selected from the 1959 head resistance. crosses. In the breeding program, straighthead-resistant selections have been obtained readily by selecting Narrow Brown Leaf Spot panicles from resistant or segregating lines for retesting in panicle rows. The number of genes Narrow broAvn leaf spot, caused by the fungus involved in straighthead reaction was not estab- CercospoTd oryzae I. Miyake, is a common disease lished, but inheritance appeared to be relatively of rice in the Southern States. There are phy- simple in crosses within the long-grain groups of siological races of the causal fungus (^6\ 73, 7If. varieties. Resistance seems to be dominant (12), 75), but genes for resistance for each race are available. The mode of inheritance of reaction to White Tip O, oryzae has been studied (4, Jiß, Ifï), No link- age between genes for reaction to Cercospora and White tip, first observed in Louisiana before those for expression of five qualitative characters 1930, was considered to be a physiological disease was found (.f5). Most of the work on the devel- until 1949, when it was found to be caused by a opment of Cercos¡)om-Y^ú^{^\\t varieties has been seedborne, foliar nematode, ApheJenchoides hes- done in the field under conditions of natural in- seyi Christie {27), However, by that time con- fection. Selection is based on type of lesion and siderable progress had been made in selecting for relative severity of infection. In Louisiana, a resistance in nurseries in which the disease oc- number of resistant selections were obtained when curred rather consistently each year. Blue Rose was crossed or backcrossed to Rexoro, After white tip was found to be caused by a although both parental varieties were susceptible seedborne nematode, various methods were used to one or more races. to insure infection in order to determine the reaction of varieties and selections to white tip. Straighthead These methods consisted of including heavily Straighthead is a physiological disease that infested seed of susceptible varieties as spreader occurs under certain environmental conditions in rows, using rice hulls containing large numbers the United States. A breeding program to de- of nematodes, or introducing nematodes from velop straighthead-resistant varieties was begun laboratory cultures into the irrigation water. in the united States in 1958, at Eagle Lake, Tex. Atkins and Todd {15) determined reaction of The method of testing consists simpl}'- of drill many rice varieties in the United States to white seeding the test entries in an area with a soil type, tip. No studies have been made on the genetics such as Hockley fine sandy loam, conducive to of inheritance. straighthead development and keeping the nurs- Hoja Blanca ery test area continuously submerged after the initial irrigation (82). The reactions of the Hoja blanca is a virus disease of rice that oc- American rice varieties (11, 12) served as a basis curs in the Western Hemisphere. In 1957, a for selecting parental varieties for resistance in a large number of United States varieties and selec- breeding program. Straighthead resistance is tions, as well as introduced varieties, were tested relative, and none of the varieties tested are for hoja blanca reaction under conditions of immune or highly resistant. The resistance of natural infection in Cuba and Venezuela {10). Bluebonnet, Bluebonnet 50, Lacrosse, Prelude, On the basis of marked differences in disease and Toro is derived directly or indirectly from reaction in the nursery tests, Arkrose, Asahi, Fortuna, selected from the Pa Chiam variety Colusa, Lacrosse, Mo. R-500, and several experi- obtained from Taiwan. C.L 5094, selected from mental varieties were designated as sources of the Sinanpagh variety from the Philippines, hoja blanca resistance for use in breeding. served as the source of resistance in Texas Patna Since both resistant and susceptible entries and the original Century Patna. ^vere found among a number of advanced-genera- Testing selections from several crosses was tion selections from two crosses having Lacrosse begim in 1954. For example, straighthead- as one parent, it was concluded that the genes for resistant selections were recovered from a cross of resistance could be readily transferred in crosses. Bluebonnet (resistant) X Century Patna 231 Other studies showed that resistance was geneti- (susceptible) and from backcrosses to Century cally controlled and could be transferred to varie- Patna 231. Although a number of the straight- ties of all grain types {22) and that resistance head-resistant selections from Ú\^ Century Patna was dominant {21). Since 1957, other lines re- 231 crosses were promising and were seriously sistant to hoja blanca have been recovered from RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 41 several crosses between susceptible and resistant ^^ested from each row, and this grain was used to parents. Thus far, none have been released as determine the cooking and processing quality of varieties. the F4 lines. Gulf rose, released in 1960 as a hoja blanca- Excellent hoja blanca readings from Colombia resistant variety (i, 28)^ was an increase of a were obtained on the F4 lines tested in 1960, as selection rated as resistant in the 1957 and subse- well as the F5 and Fe lines tested in 1961 and quent tests. Xova, released in 1963, also a hoja 1962. Hoja blanca-resistant selections were tested blanca-resistant variety (4^), was an increase further for reaction to straighthead at Eagle from a selection rated as resistant in early tests. Lake, for reaction to blast of seedlings at Beau- Testing and breeding for resistance to hoja mont, and for quality behavior in the cooperative blanca are being continued in cooperation with Rice Quality Laboratory at Beaumont. Government and private agencies m several Cen- In 1962, a number of the more promising strains tral and South American countries. Much of the carrying hoja blanca resistance were grown in testing of varieties and breeding lines for reac- advanced yield trials at Beaumont. From the tion to hoja blanca has been done under conditions crosses made in 1957, hybrid selections of early of natural infection in the field. This work has and midseason maturity and short-, medium-, and been done in foreign countries where epiphytotics long-grain types that are promising for resistance of the disease usually occur. Hybrid and back- to hoja blanca are now available for extensive cross plants and progeny lines also are tested in testing. the greenhouse where plants are inoculated with In the modification of the backcross method viruliferous vectors. Since resistance to hoja used in the hoja blanca breeding program, the blanca is dominant, backcross plants that carry Fi plant of the cross Bluebonnet 50 X Gulfrose resistance can be identified in greenhouse tests. was backcrossed to Bluebonnet 50 in 1958. A Backcross seeds are planted in the greenhouse or total of 31 backcrossed seeds produced plants. field. As soon as the plants tiller, they are di- Tlie seeds from each plant were sent to the hoja vided and part of the plant is tested for reaction blanca testing laboratory, then located at Cama- to hoja blanca. The reaction can be determined guey, Cuba, and backcross populations carrying by the time the plant flowers, so that plants carry- hoja blanca resistance were identified. Space- ing resistance can be identified and used as par- planted populations of each backcross line also ents in the backcross program. were grown in the breeding nursery at Beaumont The pedigree method, the backcross method, in 1959, and plants were selected from the lines and a modification of these two methods were that were promising for hoja blanca resistance. used in Texas to develop long-grain varieties In 1960, F3 lines were tested for hoja blanca re- resistant to hoja blanca. The material used in action in Colombia, and for straighthead reaction the pedigree method was obtained by crossing the at Eagle Lake. F2 lines were also sown at Campo long-grain variety Bluebonnet 50 and several Cotaxtla, near Veracruz, Mexico, in the fall of promising long-grain hybrid selections with 1959; and two crops per year were obtained the hoja blanca-resistant varieties Gulfrose and through 1961. Selections from the Mexico nurs- Taman-iku Xo. 487 (P.I. 215,936). The Fi ery were sent to Colombia for testing for hoja plants were grown in the greenhouse during the blanca reaction and to Beaumont for grain qual- winter of 1957-58, and the Yo populations were ity testing. By the end of 1961, many long-grain grown in the field during the summer of 1958. selections promising for hoja blanca resistance In the fall of 1958, the seeds from 353 carefully were available for extensive testing at Beaumont. selected Fo i^lants were saved. A few grams of Long-grain selections of early and midseason grain from each selection were milled in a test- maturity that are resistant to hoja blanca and tube miller, and alkali digestion and iodine-blue straighthead and that possess Bluebonnet milling, tests were performed. In 1959, progenies from processing, and cooking qualities were tested for each F2 plant were grown in Colombia, Cuba, yield and other field characters at Beaumont in and Venezuela to test their reaction to hoja 1963. blanca ; at Eagle Lake, Tex., to test their reaction Since hoja blanca resistance is dominant, Blue- to straighthead; and in the nursery at Beaumont, bonnet 50 was used as the recurrent parent in the Tex., to advance each selection on a pedigree basis modified backcross method. The ho]a blanca re- and to select on the basis of plant type and vigor. action of Fi backcross plants was obtained at the In 1960, scientists at Beaumont selected 507 hoja blanca testing laboratory at Baton Rouge, panicles from the better F3 lines grown in 1959. La. In 1963, Fi plants with four backcrosses to Seed from each of these selections was sent to Bluebonnet 50 were tested for hoja blanca reac- Colombia for further hoja blanca testing and tion. Some of these plants are similar to Blue- progeny of each was grown in the breeding nurs- bonnet 50 in plant and grain type and they are ery at Beaumont. About 20 panicles were har- resistant to hoja blanca. 42 AORICULÏUKE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE Description of Varieties spring of 1921. It is an early to midseason, partly awned variety that heads and matures uni- The names and accession numbers of the 18 formly in California and produces relatively high varieties reported in this section of the hand- yields with reasonably good milling quality on book are listed in table 9. These include the^prin- either virgin soil or old ricelands. It is the lead- cipal commercial varieties in the United States. ing variety grown in California, yields well in Arkansas {50, 51, 67) and Missouri {63), and Short-Grain Varieties yields reasonably well in Louisiana and Texas. In 1963, about 12.3 percent of the total rice Although it appears to be adapted for growing acreage in the United States was sown with short- under a wide range of conditions, it is grown grain (Pearl) varieties.^ In Arkansas, Louisiana, principally in California. Caloro is the most Mississippi, and Texas only 0.08 percent of the important short-grain variety grown in the crop produced was the short-grain type, whereas United States, in California, 67.7 percent was this type. CODY.—Cody (57) was selected from the cross The commercial short-grain varieties grown in Colusa X Lady Wright at the Biggs Rice Field yield tests were Caloro, Cody, and Colusa. Rough Station, Biggs, Calif. Seed of Cody was tested i-ice and milled kernels of each of these three va- in Missouri and then increased and distributed to rieties are shown in figure 21. These and other growers in Arkansas in the spring of 1944. Cody short-grain varieties have rather slender culms, is an early-maturing, awnless variety that can be narrow (about 3/g-inch) leaf blades, and yellow grown in all rice-producing States. It yields and or straw-colored rough hulls enclosing the kernels. mills well in the absence of diseases. It has been A plant of Caloro is shown in figure 22. When grown on a small acreage in Arkansas but has milled, short-grain varieties usually yield as high not been grown in California. a percentage of head rice (whole grain milled) as COLUSA.—Colusa {25) was selected in 1911 at do the medium-grain varieties and higher than the Rice Experiment Station, Crowley, La., from do the long-grain varieties. Short-grain varieties Chinese, a variety introduced from Italy in 1909 are not grown in the Southern States because the by Haven Metcalf. It was tested at the Biggs varieties available are not well adapted for this Rice Field Station, Biggs, Calif., and distributed area and there is little demand in this area for in 1917 and 1918. Colusa is an early-maturing, rice of this type. awnless variety of reasonably good milling qual- CALORO.—Caloro was selected from Early ity that heads and matures rather uniformly and Wataribune in 1913 at the Biggs Rice Field Sta- that produces relatively high yields on fertile tion, Biggs, Calif., and was distributed in the land. In California it is much less productive than Caloro on old riceland of average fertility. 5 See footnote 2, p. 19. However, when nitrogen fertilizer is applied at FIGURE 21.—Rough rice and milled kernels of (A) Caloro, (B) Cody, and (C) Colusa. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 43 Ut h ^ m FIGURE 22.—Plants of (A) Caloro, (B) Nato, and (C) Rexoro. TABLE 9.—Name, C.I. number., FAO number, and registration num- ber for reported rice varieties Grain type and variety C.I. FAO Registration uniform number i number - number ^ group ■* Short-grain : Caloro 1561-1 211 5 IV Cody 8642 212 20 I Colusa 1600 213 8 I Medium-grain : Arkrose ^ 8310 207 1 IV Calrose 8988 1013 6 IV Gulfrose 9416 1339 _-_ I Magnolia 8318 216 I Xato 8998 1133 13 I 9407 1364 I Zenith 7787 206 19 I Long-grain : Belle Patna 9433 1334 VI Bluebonnet 50 8990 1012 3 III Century Patna 231 8993 1014 7 II Rexoro 1779 214 14 V Sunbonnet 8989 1019 15 III Texas Patna 8321 221 16 V Toro 9013 1134 18 III TP 49 8991 1020 17 V 1 Accession number, Cereal Crops Research Branch, Crops Research Division, Agricultural Research Service. 2 Accession number, World Catalogue of Genetic Stock.s—Rice, Food and Agriculture Organization of the United Nations. 3 Registration number, American Society of Agronomy—U.S. Department of Agriculture (48). * Uniform Yield Nursery Group number. fairly high rates, it produces as much as Caloro. when the crop is heavy. Colusa has been for Colusa yields well in Missouri and fairly well on many years, and still is the most popular early- fertile land in Arkansas, but it frequently lodges maturing variety grown in California. 44 AGIUCULÏUKE HANDBOOK 289, U.S. DEPT. UF A(ÏKI Medium-Grain Varieties from the cross Caloro X Blue Rose. Arkrose was distributed in 1942. Arkrose matures about a In 1963, 47.5 percent of the rice acreage in the week earlier than Supreme Blue Rose, and in TTnited States was sown to medium-grain varie- some sections of Arkansas it is meeting the de- ties.« In California, 32.3 percent of the rice acre- mand for a Blue Rose type. Arkrose yields well age was sown to this type. Of the total rice pro- and is relatively easy to thresh. It is similar to duction in the United States, Nato made up 38.6 Blue Rose in milling and table quality. It is percent, Zenith 0.1 percent, and the Roses (prin- more difficult to dry artificially than are most cipally Arkrose, Calrose, Gulfrose, and North- long-grain varieties. Arkrose has been grown in rose) 8.7 percent. Arkansas and, rarely, in Texas. The principal medium-grain varieties grown in CALROSE.—Calrose (57) was selected at the the yield tests were Arkrose, Calrose, Gulfrose, Biggs Rice Field Station, Biggs, Calif., from the Magnolia, Nato, Northrose, and Zenith. Rough cross Caloro X Calady backcrossed to Caloro. It rice and milled kernels of each of these seven var- is a partly awned variety very similar in growth ieties are shown in figure 23. These varieties, habit and maturity to Caloro. In California, with the exception of Calrose, have rather stout Calrose appears to be equal to Caloro in yielding culms and relatively wide (about %-inch) leaf capacity and in milling quality. It stands up blades. A plant of Nato is shown in figure 22. well, matures evenly, and is as easy to combine as When milled, medium-grain varieties usually Caloro. Calrose was grown on a small acreage yield more head rice (whole kernels) than the for the first time in 1948, and in 1963 it was long-grain varieties yield. grown on 32.3 percent of the California rice ARKROSE.—Arkrose (57) was selected at the acreage. Rice Branch Experiment Station, Stuttgart, Ark., GULFROSE.—Gulfrose was selected from the 8 See footnote 2, p. 19. cross Bruinmissie selection X Zenith at the Rice- FIGURE 23.—Rough rice and milled kernels of [A) Arkrose, (B) Calrose, (O Gulfrose, {D) Mag- nolia, (E) Nato, {F) Northrose, and (Ö) Ze- nith, RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 45 Pasture Eesearch and Extension Center, Beau- Long-Grain Varieties mont, Tex., in 1953, and released in 1960 (i). It is similar to Zenith in plant and grain type In 1963, 19.1 percent of the rice ijroduced in but matures a few days earlier. Gulfrose is re- Arkansas, Louisiana, Mississippi, and Texas was sistant to hoja blanca. This was the principal the long-grain type.'^ The leading long-grain reason for releasing it since none of the leading varieties were Bluebonnet 50 and Sunbonnet, United States varieties grown at that time were comprising 33.5 percent of ih^ southern acreage ; resistant. Gulfrose was grown on a limited acre- Belle Patna, 10.6 percent; Rexoro, 2.9 percent; age in the southern rice area in 1963. and Century Patna 231 and Toro, each 1.1 percent. MAGNOLIA.—Magnolia (67) was selected at the Eice Experiment Station, Crowley, La., from the The principal long-grain varieties grown in the cross Improved Blue Rose X Fortuna. It was field tests were Belle Patna, Bluebonnet 50, Cen- released in 1945. It is an early-maturing variety tury Patna 231, Rexoro, Sunbonnet, Texas Patna, that matures about the same time as Zenith. Toro, and TP 49. Rough rice and milled kernels Magnolia usually heads and matures evenly and of each of these eight varieties are shown in figure it combines more readily than Zenith. Under 24. Most of these varieties have rather large favorable conditions it produces relatively high culms and relatively wide (about %-inch) leaf yields, with good milling quality. The grain can blades. A Rexoro plant is shown in figure 22. Î3e dried satisfactorily. Magnolia appears to be Because of the long growing season required, adapted for growing throughout the southern Rexoro, Texas Patna, and TP 49 are grown only rice area. in Louisiana and Texas. î^ATO.—Xato was selected from the cross BELLE PATXA.—Belle Patna was selected from (Eexoro X Purple-leaf) X Magnolia at the Rice the cross Rexoro X (Hill selection X Bluebonnet) Experiment Station, Crowlej', La. It was re- at the Rice-Pasture Research and Extension Cen- leased in 1956. It is an early-maturing variety ter and was released in 1961 (2). It is a very with comparatively short, strong straw; it pro- early-maturing, slender-grain variety with cook- duces good field and mill yields; and it is suit- ing quality similar to Rexoro. able for making dry cereals and for other uses for BLUEBOXNET 50.—Bluebonnet 50 was selected which varieties of similar type are adapted (43). from Bluebonnet in 1950 at the Rice-Pasture Xato was the leading rice varietv in the United Research and Extension Center. Bluebonnet States in 1963. was a progeny of the cross Rexoro X Fortuna XoRTHROSE.—Xorthrose was selected in 1955 Seed of Bluebonnet 50 was distributed in 1951. from the cross Lacrosse X Arkrose and released Bluebonnet 50 is a midseason variety. It has from the Rice Branch Experiment Station, Stutt- relatively short, stiff straw, and the grains are partly awned. It yields and mills well and has gart, Ark., in 1962. It is an early-maturing var- good cooking quality, being comparable to Rexoro iety, and its outstanding characters are its short, and Texas Patna in those characters. The grain stiff straw and high grain yields. Because of its of Bluebonnet 50 is thicker than that of Rexoro tendency to be slightly chalkier than Xato and but is more slender than that of Nira. Blue- because of its occasional low yields of head rice, bonnet 50 is well suited for harvesting by the Xorthrose was not designated for general produc- combine-drier method. tion. Instead it was designated a special-purpose CEXTUET PATXA 231.—Century Patna 231 {57) variety for relatively late seeding in northeast was selected in 1946 from a cross between Texas Arkansas where its earlmess and high degree of Patna and a selection from the cross Rexoro X lodging resistance are urgently needed (52^ 53). Supreme Blue Rose at the Rice-Pasture Research ZENITH.—Zenith {57) was selected from Blue and Extension Center. It was released to Rose in 1930 by Glen K. Alter, near DeWitt, Ark. farmers in the spring of 1951. It is an early- In 1931, several selections were tested in the co- maturing, slender-grain variety. Century Patna operative breeding program at the Rice Branch 231 usually matures about 3 days later than Experiment Station, Stuttgart, Ark. Of these Zenith. It has rather short straw and narrow, selections, Arkansas 141-8 proved to be the best ; semidrooping leaves, and tillers exceptionally it was named Zenith and distributed in 1936. well. Century Patna 231 is moderately resistant Zenith is an early-maturing, awnless variety, and to the common races of the fungus causing the it is uniform in heading and in maturing. In narrow brown leaf spot disease, so the leaves and 1954, Zenith was grown on over 50 percent of the stems remain alive for some time following ma- rice acreage in the Southern States. It has since turity. In cooking quality. Century Patna 231 is inferior to Bluebonnet 50, Rexoro, and Texas been replaced by the shorter strawed, smooth- Patna. hulled Nato variety. Strains similar to Zenith have been isolated from Early Prolific. '^ See footnote 2, p. 19. 46 AÜKICULTURE HANDBOOK 2 89, U.S. DEFT. OF AGRICULTURE FIGURE 24.—rough rice and milled kernels of {A) Belle Patna, (B) Bluebonnet .50, (C) Century Patna 231, (D) Rexoro, (£■) Sunbonnet, (F) Texas Patna, (Ö) Toro, and (H) TP 49. EEXORO.—Rexoro (25) was selected in 1926 at oro but grows slightly taller, matures about 10 the Eice Experiment Station, Crowlej', La., from days earlier, and has a more translucent grain. the Maron^-Paroc variety introduced from the It yields and mills well. Because Texas Patna is Philippine Islands in 19Í1 by the U.S. Depart- slightly taller than Rexoro, it is more inclined to ment of Agriculture. Rexoro was distributed by lodge when grown on rich land. It is well suited the Department in cooperation with the Louisiana for combining and the ^rain is easy to dry. Texas Agricultural Experiment Station in 1928. Rex- Patna is grown principally in the Eagle Lake oro is a stilf-strawed, late-maturing, slender- section of Texas and to a limited extent in grain rice that yields and mills well for a variety Louisiana. of this type. The cooking quality is very good. ToRO.—Toro was selected from a cross in which SuNBONNET.—Suiibonuet was selected from the varieties Bluebonnet, Blue Rose, and Rexoro Bluebonnet at the Rice Experiment Station, were the parents. It was developed at the Rice Crowley, La., and released in 1953 (43). Sun- Experiment Station, Crowley, La., and released bonnet is similar to Bluebonnet in plant char- in 1955 {4ß). It is similar to Bluebonnet 50 in acters, although somewhat taller than Bluebonnet plant height and straw strength. It yields and 50. Sunbonnet is similar to Bluebonnet in cook- mills well, but it is about as hard to thresh as ing quality but is usually slightly superior in Zenith. The grain type is similar to that of Blue- milling quality. bonnet, but the cooking quality of these two va- TEXAS PATXA.—Texas Patna (57) was selected rieties is different. Toro, when cooked, is firmer m 1935 at the Rice-Pasture Research and Exten- than Bluebonnet but not as dry and flaky. sion Center from the cross Rexoro X C.I. TP 49.—TP 49 (48) was selected from the 5094. Seed of Texas Patna was distributed to cross Texas Patna X (Rexoro X C.I. 7689) at the growers m 1942. Texas Patna is similar to Rex- Rice-Pasture Research and Extension Center RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 47 and released in 1951. It is a late-maturing, The glumes are less pubescent, and the grain slender-grain A^ariety, similar to Texas Patna matures 5 to 10 days later. The waxy-white ker- except that it has shorter and stronger straw and nels are opaque. somewhat thicker grain. Other Kinds of Rice Performance of Varieties Most of the rice varieties grown in the United The performance of rice varieties is studied at States are generally called common varieties ; that several rice experiment stations in the southern is, they have no distinctive flavor or odor when rice area and in California. The grain yields and cooked, and the starch in the endosperm contains milling quality data reported for the southern both amylose and amylopectin. There are, how- rice area in this bulletin were obtained from the ever, minor acreages of two other kinds of rice— Uniform Yield Nurseries from 1951 through 1961. aromatic or scented, and glutinous or waxy. In these nurseries, varieties are grown in 3- or AROMATIC OR SCENTED.—Varieties having a dis- 4-row, randomized, quadruplicated, drill-seeded tinctive odor and flavor somewhat like popcorn plots. These nurseries were grown each year in when cooked are known as aromatic or scented Arkansas, Louisiana, and Texas, and in some varieties ; they are cultivated widely in India and years in Florida and Mississippi. Yields re- other southeast Asian countries. Scented rices are ported for California were obtained from drill- said to be low yielding; but because they are seeded, quadruplicated nursery plots except in greatly esteemed, they may sell at twice the price 1960 and 1961, when the rice was seeded in the of other rices of fine quality. The odor and water. flavor are assumed to be due to an aromatic sub- Entries in the Uniform Yield Nurseries grown stance. Since aroma is sometimes noted in the in the southern rice area are grouped according growing crop, it is not limited to the endosperm. to grain type and length of growing season. The The aroma occurs in waxy as well as in ordinary six groups are: I, short- and medium-grain types of rice. early varieties; II, long-grain early varieties; Two varieties, Delitus and Salvo, were selected III, long-grain midseason varieties; IV, short- from introductions released m the United States. and medium-grain midseason varieties; V, long- Delitus has been grown commercially, and at- grain late varieties; and VI, medium- and long- tempts have been made to place it on the market. grain very early varieties. There usually were A cross between Eexoro and Delitus produced Del- 14 entries in each group, many of them experi- rex and R-D, which fully retain the flavor. R-D mental varieties, (xroup numbers of the 18 va- is a productive, medium-late variety that should rieties reported in this section of the handbook make possible profitable marketing of scented rice are in table 9, p. ^li as a food specialty. C.I. 9483, an early-maturing The varietal experiments at each location were selection from R-D X Rexoro-Zenith, has im- on soil that was typical of large areas in the re- proved milling quality and a more translucent spective States. In Florida the tests were made endosperm. on Everglades peaty muck soil. Crop rotation, GLUTINOUS OR WAXY.—Waxy varieties, com- seedbed preparation, time and rate of seeding, monly called glutinous, differ from common var- fertilization, and weed control used for these ex- ieties in that they contain only amylopectin starch periments were practices that were thought to in the endosperm. Glutinous rice is grown on l3e optinmm for each area. about 1,000 acres in California each year. It is Average grain yields in table 10 were obtained grown as a specialty crop, and the acreage needed from 1951 through 1961 at the following loca- to meet market demands has been small. His- tions: Rice Branch Experiment Station, Stutt- torically, the principal use of glutinous rice has gart, Ark.; Everglades Experiment Station, been for preparing oriental ceremonial foods and Belle Glade, Fla.; Rice Experiment Station, confections. In some countries, glutinous rice is Crowley, La.; Delta Branch Experiment Station, harvested slightly green, is lightly parched before Stoneville, Miss. ; Rice-Pasture Research and milling, and is used as a breakfast food. Recent Extension Center, Beaumont, Tex. ; and Rice research has shown that glutinous rice flour may Experiment Station, Biggs, Calif. The actual find a special use in the frozen food industry. number of years each variety was tested is The flour, when made into foods for freezing, shown. The yield of each variety is compared such as white sauce and desserts, resists syneresis with the yield of one or two standard varieties (separation or weeping) when thawed after that were grown throughout the entire period. freezing. In Arkansas, the short-grain varieties all pro- Mochi Gomi is the variety of this type grown duced the highest average yields except those of in California. It is a short-grain, midseason the medium-grain varieties Arkrose and North- variety. Compared to Caloro, it has about the rose. All medium-grain varieties except Mag- same straw strength and is about 6 inches shorter. nolia produced higher average yields than did TABLE 10.—Grain yield for 18 rice varieties grcnon at 6 locations during the 11-year period, 1951-61 Arkansas Florida r .ouisiana IVl[ississippi Texas California Grain type and variety Years Y^ears Years Years Years Yield 1 Y ifddi Yie Years grown grown grown Id i grown Yield 1 grown Yield 1 grown Yield 2 Number Pounds Percent Number Pounds Percent Number Pounds Percent Number Pounds Percent Number Pounds Percent Number Pounds Percent Short-grain : Caloro 11 4201 lOi) 5 2023 61 10 2852 91 6 5836 129 9 3314 94 11 3375 100 Cody 10 4149 111 5 2559 78 10 3423 113 5 4034 89 10 3642 100 Colusa 11 4242 110 5 2862 87 11 2743 88 6 4036 90 11 3754 103 11 3555 105 Medium-grain : Arkrose 11 4^38 112 5 3344 101 10 3080 98 6 6064 134 9 3575 101 Calrose 11 4174 108 5 2073 63 10 2721 87 6 5514 122 9 3134 89 11 3544 105 Giilfrose _ 4 4715 107 4 2804 80 3 4715 103 4 3559 90 Magnolia 11 4008 104 5 2806 85 11 3114 100 6 4273 95 11 3454 95 Nato 10 4510 109 5 3640 110 10 3250 107 6 4477 99 10 3786 103 North rose 4 4933 112 4 3802 109 3 5337 117 4 4158 105 Zenith 11 415(; 108 5 3232 98 11 3231 104 6 4227 94 11 3593 98 Long-grain : Belle Patna 4 3834 87 4 3245 93 3 4543 99 4 3476 87 Bluebonnet 50 _ n 3556 92 5 3365 102 11 3012 96 6 4791 106 11 3703 102 Century Patna 231 11 4128 107 5 3350 102 11 3674 118 6 5083 113 11 3540 97 Rexoro 11 2128 68 11 2676 73 Sunbonnet 11 3592 93 5 3758 114 11 2922 94 6 4863 108 11 3827 105 Texas Patna 11 2404 77 11 3009 82 Toro 10 4113 100 5 3594 109 10 3237 106 6 4869 108 10 3738 102 TP 49 11 2417 77 11 3269 90 1 Percent of the yield is based on the mean of Zenith and Bluebonnet 50 for the years grown ; quantity given in pounds per acre. 2 Percent of yield is based on the yield of Caloro. RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 49 most of the long-grain varieties. Century Patna before milling was described in the section ''Test- 231 produced nearly the same average yield as ing for Milling, Cooking, and Processing Quali- the medium-grain varieties, but the other long- ties,'' p. 33. The average milling yields of hulls grain varieties produced lower average yields. ranged from 18 percent for the short-grain varie- In Florida, none of the short-grain varieties ties Caloro and Colusa to 21 percent for the produced an average yield that was as high as long-grain variety Century Patna 231. Average that of the higher yielding medium- or long- bran yields ranged from 9 percent to 13 percent. grain varieties. Of the medium-grain varieties, In general, bran jâelds were lower for short- and Nato produced the highest average yield. The medium-grain varieties than for long-grain va- long-grain variety Sunbonnet produced the high- rieties. Northrose, a newly released, special-pur- est average yield of any variety. pose, medium-grain variety yielding an average In Louisiana, Cody was the only short-grain of 12 percent bran, was an exception. The late- variety that pi*oduced an average grain jâeld maturing, long-grain varieties Eexoro and Texas comparable to the jàelds of the higher yielding Patna grown only in Louisiana and Texas pro- medium- and long-grain varieties. The highest duced the highest bran yields (13 percent) of any yielding medium-grain varieties were Nato and of the varieties tested. Zenith, except for Northrose, which was grown The average yield of total milled rice varied only 4 years. Of the long-grain varieties, Cen- from 67 percent for Century Patna 231 to 73 tury Patna 231 and Toro produced high average percent for Caloro and Colusa. Short-grain va- yields. The late-maturing, long-grain varieties rieties, as a group, produced slightly higher feexoro, Texas Patna, and TP 49 produced quite yields of total milled rice than did medium- and low yields. long-grain varieties. The medium-grain variety In Mississippi, Caloro produced the highest Northrose and the long-grain varieties Century average yield of the short-grain varieties tested, Patna 231, Rexoro, and Texas Patna gave the but the other two short-grain varieties produced lowest total milled rice yields. quite low yields. Arkrose, Calrose, and North- Head rice yields for the varieties listed in ta- rose produced highest average yields of the me- ble 7 are reported as average values and as indi- dium-grain varieties tested. The average yield of vidual minimum and maximum (range) values. these three varieties was somewhat higher than Average yields of head rice varied widely among that of the long-grain varieties. Of the long- the varieties, from 52 percent for Rexoro to 69 gram varieties, Century Patna 231 produced the percent for Calrose. In general, the average highest yield. All long-grain varieties except yield of head rice was highest for the short- and Belle Patna produced higher average yields than medium-grain varieties and lowest for the long- did many of the commonly grown medium-grain ^rain varieties. Toro, a long-grain variety yield- varieties. mg 67 percent of head rice, was an exception. In Texas, the short-grain varieties Cody and The milling qualitj^ of this variety has been noted Colusa produced average yields comparable to in earlier publications (iP, 41)- Individual the higher yielding medium- and long-grain va- minimum and maximum values of head rice rieties. Of the medium-grain varieties, Nato and yields also varied widely. This variability was Arkrose produced highest average yields except evident, not only among varieties but also within for Northrose, which was grown only 4 years. the varieties. Individual minimum head rice Sunbonnet, Bluebonnet 50, and Toro produced yields ranged from 33 percent for Arkrose to 63 highest average yields of the long-grain varieties. percent for Calrose, Magnolia, and Nato; where- In California, Colusa and Calrose produced as individual maximum values ranged from 61 slightly higher average yields than did Caloro. percent for Rexoro to 75 percent for Colusa. The average number of days from seeding to maturity, average plant height, estimated straw Choosing the Variety strength, and pubescence and color of hull for the 18 varieties included in this handbook are given Several factors affect the choice of a variety. in table 11. These are listed by Johnston, Cralley, and Henry Milling quality was determined each year for (51) as market demand, satisfactory yielding the varieties grown in the Uniform Yield Nurs- ability, location, proposed seeding date, soil fer- eries. Included in table 7, p. 36, are the average tility or anticipated fertilizer practices, relative milling yields of hulls, bran, total, and head rice maturity, susceptibility to diseases that may oc- for each of 18 varieties grown in the Uniform cur, and seed supply. Growers of large acreages Yield Nurseries in Arkansas, Louisiana, and may wish to sow two or three varieties that differ Texas for the years 1958-61. Milling yields were in date of maturity and grain type in order to determined according to the modified procedure extend the harvesting period and to provide rice of Beachell and Halick (19), Treatment and of different types for the market. preparation of Uniform Yield Nursery samples A grower should carefully consider market re- TABLE 11.—Plœnt characters for 18 rice varieties grown, at 6 locations during the 11-year period, 1951-61 Average time from seeding to maturity - Average plant height Estimated Hull Grain type and variety straw pubes- Hull Arkan- Flor- color Loui- Missis- Texas Cali- Arkan- Flor- Loui- Missis- Cali- strength 3 cence 4 sas ida siana sippi fornia sas ida siana sippi Texas fornia Days Days )ays Days Days Days Inches Inches Inches Inches Inches Inches Short-grain : Caloro 141 149 145 133 138 153 46 31 44 39 46 35 Weak R Straw. Cody 129 127 122 5 124 119 44 36 42 39 46 Midstrong_ R Straw. Colusa 130 128 123 124 118 134 46 37 43 36 47 34 Very weak. R Straw. Mediiim-^ain : Arkrose 150 153 150 144 142 52 44 50 47 52 Very weak R Straw. Calrose 141 148 143 129 137 153 46 32 43 37 46 33 Weak R Straw. Gulfrose 126 121 123 116 48 43 37 47 Weak S Straw. Magnolia 134 127 127 131 121 51 45 46 42 50 Weak R Straw. Nato 132 127 126 130 122 47 41 42 41 47 Midstrong. S Straw. Northrose 134 130 128 123 46 42 37 43 Strong S Straw. Zenith 133 129 126 134 122 50 44 46 44 50 Midstrong. R Straw. Long-grain : Belle Patna 115 108 118 109 43 42 36 45 Weak S Straw. Bluebonnet 50 149 145 140 147 137 47 44 45 49 50 Strong S Straw. Century Patna 231 136 133 131 137 126 47 37 43 44 48 Strong s Gold. Rexoro 174 172 50 52 Strong s Gold. Siinbonnet 148 143 140 147 137 52 47 48 51 54 Strong s Straw. Texas Patna 166 149 50 55 Very weak s Gold. Toro 148 144 140 148 137 '49' 44 45 Is' 49 Strong s Straw. TP 49 172 165 48 52 Weak s Gold. 1 Years of test : Arkansas, 1951-61 ; Florida, 1953-56 ; Louisiana, 1951-61 ; Mississippi, 1959-61 ; Texas, 1951-61 ; and California, 1951-61. 2 Average seeding date: Arkansas, May 7; Florida, March 31; Louisiana, April 17; Mississippi, May 18; Texas, April 24; and California, May 6. 3 Based on results for Arkansas and Texas. ^ R = pubescent ; S = glabrous. 6 2-year average. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 51 quirements in selecting varieties to grow. He or Rose matured in shorter periods of time when his marketing agent may have difficulty in selling sown late than did Bluebonnet (5). Varieties his rice if it is of poor quality, even though that responded to the sliortened days of late sum- locally the variety may produce high yields. mer by [leading at nearly the same date whether Also, growing a short- or medium-grain variety seeded early or late were termed photosensitive. on a limited basis in an established long-grain They also headed out quickly and uniformly. district, for example, can pose real problems to Length of time required for the photosensitive the grower, driers, warehousemen, and millers varieties to reach the heading stage decreased to prevent mixtures of the different types. with each delay in the seeding date; plant height Seeding rice on highly fertile soil, such as also decreased. Varieties that did not continue newly cleared woodland, ''new ground,'' or a field to shorten their growing period in response to used as a reservoir just before being seeded to late seeding were termed indiiferent. rice, would necessitate the choice of a stiff'- In Louisiana, the maximum number of days strawed variety that would be less likely to lodge. to flowering resulted from seedings on March 1 Even on old riceland low in natural fertility, if or March 15, except for the variety Caloro (37)^ a grower anticipates using heavy rates of nitro- in an experiment reported in 1936. The mini- gen fertilization, with part of it applied rela- mum for all varieties Avas from June 15 seedings. tively late, such a practice nvàj make it desirable The difference between maximum and minimum to choose a relatively early-maturing variety. days to flowering was a varietal characteristic. Growers in the northern part of ricegrowing Some varieties tended to have a comparatively areas in the United States are limited to early- fixed growing period; others tended to head at maturing varieties because of the somewhat a certain date late in the season, and if sown shorter growing season and cooler night tempera- late, their growing periods were shortened mate- tures than those prevailing farther south. It rially. The maximum number of days from first may be desirable to avoid a given variety because heading to full maturity was 45; this number of its susceptibility to a certain disease when rice added to the number of days to flowering for is to be grown under conditions known to be each variety gave the total length of the growing favorable for development of that disease. period. Another field plot experiment with six varieties Varietal Response to Seeding Date was conducted over a 5-year period in Louisiana and reported in 1944 (38), The seeding dates By NELSON E. JODON were approximately the 15th and the 1st of each month from March 15 to June 15. Best yields Results of Tests With Older Varieties were obtained from April 1 and May 1 seedings. Growers need to know how rice varieties will Lower yields Avere obtained from June seedings respond when sown at various dates. They should than from April and May seedings. be able to tell the probable effect on yield, days The rice varieties Bluebonnet, Magnolia, Rex- to full maturity, plant height, milling quality, oro, and Zenith were grown in a date-of-seeding and other characters. Date-of-seeding tests have test in Louisiana and reported in 1958. In all, been conducted at Arkansas, Louisiana, Texas, 27 seedings were made on dates as early as Feb- and California rice experiment stations. ruary 20 and as late as June 20 in the years 1941 At Stuttgart, Ark., an experiment was carried to 1952 (40). Usually, four seedings were made on for 5 years with 10 varieties seeded at three each season. A tabular guide (40) for use in dates (5)^ The average seeding dates were April planning seeding schedules gave, for alternate 20, May 11, and June 5. Bluebonnet and Blue days during the planting period, the growing Rose yielded well from the first two seedings but season midpohit date (latest date to topdress), usually matured too late when seeded in June. date of first heading, date when mature for com- Arkrose yielded about the same from each of the bining, and total length of the growing period. seeding elates. The highest average yields from Xine varieties were seeded monthly from mid- the latest seeding were made by Cody and Zenith, March to mid-July in a 3-year experiment con- which have shorter growing seasons. ducted at Beaumont, Tex., (72) and reported in Most varieties sown in June in Arkansas risk 1954. Yields of early varieties showed no defi- injury by possible October frosts, although Ark- nite relation to seeding date, but midseason va- rose and Zenith seeded in mid-June and Caloro rieties gave markedly lower yields from May and Cody seeded late in June have produced and later seedings. Late varieties gave the best satisfactory yields (51). Xato should be seeded yields from the earliest seedings and failed to before the first of June and Bluebonnet by May mature from June and July seedings. 25. In the northern part of the State, seeding Effects of 10-hour daylight periods on length should be 7 to 10 days earlier. of growing period were studied in Texas (Ï7). In an Arkansas experiment, Arkrose and Blue The day length was reduced by covering the 52 AUKiCMlJIí ~iE HANDBOOK 2895 U.S. DEPT, OF AGRICULTURE plants part of each da>. SimiJar results were they were not necessarily the same from year obtained from the 10-, 20-, and 30-day periods to year. of short-day treatment. Two groups of varieties, LENGTH OF LIFE CTCLE IN RELATION TO SEED- termed sen'sitive and less sensitive, were com- ING DATE.—Average number of days from seed- pared. Varieties in the sensitive group showed ing to first heading by monthly seeding date for a marked reduction in the number of days from six varieties representing four maturity groups seeding to headhig when the treatments began are summarized in table 12. Date of first head- about 50 days after seeding. The less sensitive ing was used as the criterion of the length of varieties in general responded only slightly growing season of varieties, since it can be de- from the 50-day treatment but responded more termined more precisely than date of maturity. when the treatments were started 60 to 80 days The length of the period from first heading to after seeding. The response depended on the maturity ranged from 35 to 40 days for the varie- variety. Reduction in length of growing period ties listed. During warm w^eather, however, va- was accompanied by reduction in number of rieties that head very evenly may ripen in 30 tillers and panicles, plant height, and straw and days after the tips of panicles first emerge from grain weight. the boot; whereas late in the growing season, the At Biggs, Calif., a date-of-seeding test was period from panicle emergence to full maturity conducted for 9 years {54), Three seedings of may be 45 to 50 days. the Wataribune variety were made each year, Relative heading dates of five of the six varie- beginning as early as possible m the spring. The ties were fairly constant when sown at succes- seedings were made at 2-week intervals. In all sively later dates, although the number of days but 1 year's test, the highest yields were obtained from seeding to heading was progressively fewer. from the earliest seeding. Nato headed 14 to 18 days earlier than Sunbonnet or Toro. Sunbonnet and Toro headed 12 to 19 Results of Tests With Newer Varieties days earlier than R-D. Rexoro was 9 to 17 days and Selections later than R-D. The number of days from seed- ing to heading for Blue Rose decreased more Tests similar to those reported in 1953 (40) than some varieties as seeding was delayed. Blue were continued in Louisiana in the 9 vears from Rose headed 1 day later than R-D when sown 1953 through 1961 (44, pp. 8-25). In these ex- in March; but when sown in June, it headed 19 periments, seedings were made each year in days earlier than R-D and 7 days earlier than March, April, May, and June, Each year the Sunbonnet. seedings were made to coincide with peaks of The reduction of length of life cycle of Blue planting operations on farms in the area. En- Rose from successive seedings is an example of tries included varieties from four maturity photoperiodic response. This response is gov- groups. These included Nato (early), Sunbonnet erned by the length of the dark period during and Toro (midseason), Blue Rose and R-D the 24-hour day. Blue Rose may be termed pho- (medium late), and Rexoro (late). They mature tosensitive and the other varieties may be said in about 120, 135, 150, and 165 days, respectively. to have relatively inflexible growing seasons be- Extra early types (100-day group) were first cause their life cycles tend to remain constant in included in 1957. One or two standard varieties length once a certain minimum has been reached. representative of each maturity group were tested For example. Nato seeded in June reached ma- throughout the 9-year period. Each year addi- turity in only 4 days less time than when it was tional entries of current interest were included. seeded in May. Data for individual varieties are used in the Low^ temperatures in the early spring retard following discussion of length of life cycle. Data germination and seedling development, thus ex- for yield, height, and milling quality were aver- tending the length of the life cycle. Average ages of a standard variety and two other varieties lengths of life cycles from April seedings were or selections belonging to each of the four ma- 17 days less than from March seedings. Those turity groups, except in the late group. In the from May seedings were only 8 days less than late group, data for only Rexoro and one selec- from April seedings, and those from June seed- tion were used for 2 of the years. The early ings were only 9 days less than from May seed- group included Nato and two other varieties ; the ings. midseason group, Sunbonnet, Toro, and one other The greater reduction in number of days from variety; the medium-late group, Blue Rose, R-D, seeding to maturity in April as compared with and one other variety; and the late group, Rexoro March seeding was caused by greater temperature and one other variety. Thus, the three varieties differences that occur between April and later mcluded in maturity-group averages for each seeding dates. The further reduction obtained month of the seeding period were the same in from May and June seedings probably was any 1 year; but, aside from the standard variety, largely the result of photoperiodic response. Be- RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 53 TABLE 12.-—Average days fro7n seeding to first heading of 6 rice varieties representing ^ maturity groups^ when sown in each of the 4 months of the planting period in the years from Í95S to 1961 Time of seeding Maturity group and variety Average March April May June Early : Days Days Days Days Days Nato 103 88 80 76 87 Midseason : Sunbounet 118 103 98 93 103 Toro 118 102 96 90 102 Medium-late : Blue Rose 137 115 102 86 110 R-D 136 121 115 105 119 Late: Rexoro 153 137 127 114 133 Average 128 111 103 94 cause of slow ripening late in the gTowing season, curve for each variety, representing the earlier very late seeclings tend to lengthen the life cycle part of the planting period, tended to be steep, rather than reduce it. because when the weather warmed in the spring, Seven varieties that mature in from 100 to 165 the length of the period from seeding to heading days were sown at four successive dates each year was rapidly reduced. Further reduction in time from 1953 to 1961. The response of these varie- until heading for five of the seven varieties pro- ties is shown in ñgure 25. The upper part of the ceeded at a slower but comparatively uniform 3-20 Belle Patna Nato Sunbonnet Blue Rose R-D Rexoro C.I. 6001 DATE OF HEADING FiGUEE 25.—Heading date in relation to seeding date of 7 adapted varieties grown at Crowley, La., from 1953 to 1961. 54 AGB! Oí UKE HANDBOOK 2 8 9, U.S. DEPT, OF AGRICULTURE rate through the remainder of tîie season. Con- age yields of variety groups by monthly seeding sequently, the curves indicating the response of dates are summarized in table 14. Production those five varieties are roughly parallel. of the early varieties varied but little because of Blue Rose and C.I. 6001 had steeper curves date of seeding. Midseason and medium-late than did the other five varieties. This reflected varieties Avere less productiAœ from June seedings greater sensitivity to photoperiod. C.I. 6001 Avas than from earlier seedings. Yields from May later than R-D Vnd Rexoro when seeded early seedings of Rexoro and other late varieties were but became earlier from subsequent seeding. Blue reduced. Yields from June seedings were un- Rose Avas later than Sunbonnet when seeded early profitably IOAV or were complete failures. but became earlier from subsequent seeding. Probably Rexoro should not be seeded after Early-maturing varieties do not shoAv the char- about May 20 at the latest (^0), and April seed- acteristics of photoperiodic response, otherwise ing is preferred. Currently, no medium-late va- they Avould not head during the long days of rieties, such as Blue Rose, are in production. June and July. Or possibly the critical length These have been replaced by early-maturing, of the dark period is much shorter for them than medium-grain A^arieties. The midseason varieties for the more sensitive later varieties. Bluebonnet 50 and Sunbonnet may be seeded in All varieties have a vegetative stage of devel- Louisiana as late as the first week of June with opment during which they are not photosensi- satisfactory results. Nato and other early varie- tive. The less sensitive midseason and later ties may be seeded in Louisiana at any time from varieties may have a longer vegetative stage than early March to the end of June with expectation do the early A^arieties. of profitable yields. In some years blast may be Sensitive and short-season (early) varieties serious during the warm humid weather in the may be seeded later than less sensitive midseason summer months. During years when this disease or ïate A^arieties. HoAvever, Arkrose and Caloro is prevalent, there may be a reduction in stand are the only sensitive varieties noAv in production. of late-sown susceptible varieties. There may at Any of the less sensitive A^arieties can be used for the same time be a reduced yield from early- successiA^e seedings because the plants mature in the order seeded, and the fields can be liarA^ested soAvn, short-season A^arieties caused by the rotten- Avithout conflict. neck phase of blast. Data obtained from date-of-seeding experi- PLANT HEIGHT IN RELATION TO SEEDING DATE. ments may be used to predict time of maturity —A Average plant heights of four groups of varie- of rice A-arieties. This information makes it pos- ties by monthly seeding ranges are summarized sible to schedule seedings so that different fields in table 15. Midseason and late A^arieties were and varieties may be harvested consecutively. taller than were early A^arieties. Midseason va- The approximate dates of maturity of eight A^a- rieties seeded in June and late A^arieties seeded rieties Avhen soAvn at 10-day intervals, March 1 in May and June were shorter than when seeded to June 30, in southwest Louisiana are shown in earlier. Adair (3) reported that in Arkansas table 13. later seedings produced shorter straw, and Beach- YIELDS IK RELATION TO SEEDING DATE.—Aver- ell (17) found a marked reduction in plant TABLE 13.—Approximate dates of vimturity of 8 rice varieties when sown at 10-day intervah in sauthwest Louisiana Seeding date BeUe Patna Gulfrose Nato Bluebonnet, Sunbonnet, Texas Patna Rexoro or Toro Mar. 1. 7-13 7-25 7-28 8-13 9-8 9-18 10 7-17 7-27 7-30 8-15 9-20 20 9-11 7-22 8-2 8-4 8-22 9-15 9-25 30 7-26 8-4 8-9 8-27 9-21 10-2 Apr. 10 8-2 8-13 8-16 20 8-31 9-27 10-6 8-9 8-21 8-22 9-5 10-3 10-13 30 8-14 8-27 8-30 May 10 9-15 10-7 10-19 8-21 8-31 9-5 9-21 10-13 10-25 20. 8-29 9-4 9-15 30 10-1 10-18 10-30 9-5 9-12 9-24 10-11 10-25 11-^ June 10. 9-13 9-23 9-30 20 10-18 11-3 11-15 9-26 10-4 10-9 10-25 11-12 30. 10-8 10-16 (^) 10-17 11-4 (1) (1) 1 Failed to mature. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 55 TABLE 14.—Average yields of 3 rice varieties in each of If maturity groups, from seediiigs raade in each of the Jp months of the planting period in the years from 1953 to 1961 Maturity groups Time of seeding Average Early Midseason Mediuni.-late Late Pounds per acre Pounds per aere Pounds per acre Pounds per acre Pounds per acre March 2,771 2,740 2,634 2,521 2,667 April 2,674 2,744 2,852 2,324 2,649 May 2,604 2,632 2,826 2,172 2,568 June 2,623 2,395 2,452 1 1,197 2 2,167 Average 2,668 2,628 2,691 3 2,054 1 Late varieties failed in 1954 and 1957. - Average of June seedings, late group excluded, 2,490. 3 Average of late varieties, June seeding excluded, 2,339. TABLE 15.—Average plant heights of 3 rice varieties in each of 4 maturity grcjups, from seedings made in each of the 4 months of the pJanting period in the years from 1953 to 1961 Maturity groups Time of seeding Average Early Midseason ]\Iedium-late Late Inches Inches Inches Inehes Inches March 43 47 49 49 47 April 44 47 50 49 48 May 44 47 49 48 47 June 45 46 45 45 45 Average 44 47 48 48 height of varieties that headed in response to a of the lack of correspondence in grain type of 10-hoiir photoperiod. the varieties within groups. The reductions in average heights from later March seeding resulted in low percentages of seedings, as shown in table 15, correspond to re- head rice, probably because of higher tempera- duced yields in the respective months, as shown tures during the maturation period. Ripening in table 14. is hastened in hot weather, and more chalky A correlation of 0.25 between height and yield grains are produced. Also, rapid changes in within individual varieties from seedings in the temperature and moisture tend to cause check- earlier months indicates that higher yields tend ing of the gi^ain. Compared to March seedings, to be associated with greater plant heights from April and May seedings gave improved milling early, medium, or late seeding dates. This does quality. The average percentage of head rice not mean that short-strawed varieties necessarily was 3 percent higher from May than from April tend to be low yielding. However, among fields seedings. of the same variety, plants with taller straw are The average percentages of head rice from likely to be higher yielding than those with May and June seedings were equal. However, shorter straw. Exceptions to this generalization the midseason and especially the late varieties may occcur when nitrogen fertilizer is applied at were lower in milling quality from June seed- different times. ings, probably because of effects of low tempera- MILLING QUALITY IN RELATION TO SEEDING tures late in the season. DATE.—Average percentages of head rice from The early and medium-late, medium-grain va- varieties representative of four groups are sum- rieties tended to give increasingly higher per- marized according to monthly seeding date in centages of head rice from each successive seed- table 16. No comparison can be made of the ing. Thus, apparently improved milling quality average milling quality of these groups because is a major advantage of late seeding. 56 ÍRLiJUL/rulíJS HzVKDBOOK 2 8 9, U.S. DEFT. OF AGRICULTUKE TvBLE IQ,—Average perrent.ï./e^; of head rice from samples of S rice rarieties m each of Í maturity groups, from seedings vutde ¡n each of the if months of the planting period in the years from 1953 to 1961 ' Maturity groups Time of seeding Average Early Midseason Medium-late Late Percent Percent Percent Percent Percent March 57 53 49 47 52 April 60 56 54 49 55 May 60 61 57 52 58 June 65 59 58 48 58 tification but other factors, such as weeds, diseases, Production of Seed Rice viability, mechanical purity and grading are also im- portant. One of the most effective methods of prevent- By T. H. JOHNSTON ing the wider distribution of weeds is to plant weed- free seed. Adverse effects of plant diseases can be re- Origin of High-Quality Seed Rice duced by planting clean seed from disease-free fields. Properly cleaned and graded seed is easier to plant and According to Wise (88), new and superior gives more uniform stands. varieties of crops make their intended contribu- Seed certification is designed, therefore, to maintain tions to agriculture only ''when the seed stocks not only the genetic purity of superior crop varieties, of such crops reach the farmer varietally pure, but also reasonable standards of seed condition and quality. in a viable condition, free of noxious weeds, in It also is stated in this publication : adequate quantities and at a reasonable price." Only those varieties that are approved by a State or To produce this high-quality seed, a grower Goverumental agricultural experiment station and ac- must have a source of superior seed of a well- cepted by the certifying agency shall be eligible for adapted variety. Promising new strains are certification. compared to standard varieties continually at the In general, before a variety is approved by an rice experiment stations to determine their adap- experiment station, it must be tested thoroughly tation. When an experimental strain proves to (usually for a minimum of 3 years), and it must be superior to standard varieties, it is increased show merit as a new variety in production, dis- for release to growers. ease resistance, or some other outstanding Formerly each farmer could obtain a small character. amount of seed of a new or standard variety and thereafter produce his own seed. However, mod- Classes of Seed in a Certification Program ern harvesting and processing methods, including bulk drying and storage, have increased the The classes of seed usually included in a cer- possibility of mixing. These methods and the tification program are breecler, foundation, reg- use of more specific types of varieties that dif- istered, and certified. These are described by the fer in maturity, grain type, and processing and International Crop Improvement Association cooking quality have emphasized the need for [36) as follows: sources of pure seed. As a result, the seed cer- (1) Breeder seed is seed directly controlled by tification program now in effect in each major the originating, or, in certain cases, the sponsor- rice-producing State is an important part of the ing plant breeder or institution, and which pro- rice industry. vides the source for the initial and recurring "Minimum Seed Certification Standards'' (36) increase of foundation seed. states : (2) Foundation seed- shall be seed stocks that The purpose of Seed Certification is to maintain and are so handled as to most nearly maintain spe- make available to the public sources of high quality cific genetic identity and purity and that may seeds and propagating materials of superior varieties be designated or distributed by an agricultural so grown and distributed as to insure genetic identity. Only those varieties that contain superior germ phasm experiment station. Production must be care- are eligible for certification. Certifie<:l seed is high in fully supervised or approved by representatives varietal purity and of good seeding value. of an agricultural experiment station. Founda- Varieties eligible for certification have resulted either tion seed shall be the source of all other certified from natural selection or through systematic plant breeding In either case without a planned method of seed classes, either directly or through registered maintaining genetic purity, there is grave danger of seed. Wliite tags are used to designate this class losing varietal identity. of seed. Varietal purity is tlie first consideration in seed cer- (3) Registered seed shall be the progeny of RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 57 foundation or registered seed that is so handled pliasis is given to noting albino seedlings or vari- as to maintain satisfactory genetic identity and able plant types. Later in the season special purity and that has been approved and certified attention is paid to uniformity of vegetative by the certifying agency. Purple tags are used growth and heading within and among rows. to designate this class of seed. During tlie ripening period, careful observations (4) Certißed seed shall be the progenies of are made to detect differences in plant type, plant foundation, registered; and, in some cases, pre- height, panicle type, f)ubescence, color of apex or viously certified blue tag seed that is so handled apiculus, and grain type. If the entire group of as to maintain satisfactory genetic identity and panicle rows appears uniform, the rows are har- purity and that has been approved and certified vested in bulk. by the certifying agency. Blue tags are used to However, if considerable variability attributed designate this class of seed. to genetic segregation is evident or if numerous For the production of the various classes of offtype plants are found, then it may be neces- certified seed, it is necessary to have clean land saiy to make further selection of rows for puri- and to prevent mixtures in seeding, harvesting, fication. This ma}^ be done by selecting from and processing. Although careful roguing of all within a block of rows individual rows that ap- fields to remove undesirable weeds, other crops, pear to be uniform in appearance and that typify or offtype plants increases the production costs, the variety being increased. it is necessary. The grain from 30 to 50 or more such rows The production of breeder and foundation seed (families) may be harvested separately after 25 is an integral i^art of the cooperative rice-breed- to 100 panicles are selected from each row. A hig projects of the U.S. Department of Agricul- number is assigned to each family for maintain- ture and the Agricultural Experiment Stations. ing its identity. The following year, from 10 to The production and ceitification of registered 20 or more rows may be sown from the bulk seed and certified seed are not a part of the breeding of each family, or a similar number of panicle program. rows from panicles saved from each familj^ row BREEDER SEED PRODUCTION.—After an experi- may be used instead of the bulk. mental variety of rice has been developed in the An alternate method would be to select a few coordinated breeding program and has been panicles from all rows that appear to be typical proved sufficiently outstanding, procedures are of the variety and grow three to six panicle rows begun to purify it and to provide a seed supp)ly of each row. for possible release to growers for commercial The panicles saved from each family row are production. examined individually for off'tj^pes and are grown Procedures differ at the various experiment by seeding each family in a group or block of stations but the steps included usually are some- 3 to 25 or more panicle rows. As before, the what as follows: (1) From 100 to 500 panicles rows are observed for offtype or undesirable type are selected from the interior rows of nursery or plants in the seedling and later stages. If several field plots of the experimental varietj^; (2) these off'types are found within a family or if the rows panicles are Aveighed and the weight is added to within a family tend to be variable or are not the plot weight so as not to cause inaccurate plot typical of the variety, tlie entire family may be yield reports; (3) each panicle is inspected and eliminated. If tliere still appears to be too much any having offtype seeds is discarded; (4) each variation in the material, it ma^^ be necessary to panicle typical of the variety is tlireshed indi- again select individual rows from families most vidually; and (5) the seeds are placed in a small similar in plant type. Several rows may be se- envelope. lected from each of several families, again identi- The following year the seed from each panicle fying the families and subfamilies, and the sub- that passed the screening test is sown in a single families grown in panicle-row blocks the following row from 4 to 20 feet long and 12 to 24 inches year. Usually at tliis stage the material is suffi- apart. In some cases there are 3-foot alleys be- ciently uniform, so tliat there are only a few off- tween ranges of rows to facilitate careful inspec- types to discard or eliminate. tion and roguing. The block of panicle rows of If a variety needs to be released as soon as each variety is isolated from those of varieties possible because of a disease emergency, for ex- similar in maturity so as to eliminate natural ample, one procedure would be to increase and crossing and subsequent segregation for oft'typjes. release seed at an earlier stage and at a designa- After the seedlings emerge, they are carefully tion lower than foundation seed. Purification of inspected at intervals to identify any off'type the variety could be continued and foundation plants or rows. Rows that show offtype plants seed could be released as soon as it becomes or any apparent dift'erences at any stage are re- available. moved immediately or tagged for removal before It may be desirable to check the processing harvest. In the early seedling stage, special em- and cooking quality of the bulk seed from each 58 AGRICULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE family row used in the puriHcation increase. as a field being grown for production of foun- Useful quality tests are the alkali digestion {65) dation seed. Depending on the facilities avail- and iodine-blue tests {34.). The final bulk rep- able and the amount of seed desired, individual resenting all the family lines should be grown panicles may be selected in quantities varying in varioty trials to determine the overall per- from 500 to possibly 5,000. These panicles are formance of the mass-selected strain. carefully inspected and those that are typical for One method used to produce breeder seed of the variety are threshed individually and head established varieties is to select panicles from the rows are grown (fig. 26). best available source of seed of that variety, such One procedure that has helped to eliminate immm FiGUKE 26.—Breeder seed head-row block. natural crosses with other varieties has been to method should be used as a last resort, since seed the block of breeder panicle rows within the severe mass selection may result in genetic altera- area of a foundation field of the same variety. tion of the original variety. Each I'ow must be examined carefully through- An alternate method used for the production out the growing season and atypical rows elimi- nated. Failure to eliminate a row with a few of breeder seed of established varieties is to start ofitype plants will adulterate the seed produced, with the best source available and, depending on and It must be discarded. Typical rows are the amount of breeder seed desired, to carefully bulked. The family method described for se- handpick a given quantity of seed to eliminate lecting new varieties may be necessaiy if a com- grains that appear to be offtype or to have other mercial variety becomes badly mixed. But this unclesirable characteristics. This handpicked seed can be drilled thinly, possibly at one-fourth RICE TN THE UNITED STATES ! VARIETIES AND PRODUCTION 59 the normal rate, in rows 50 to 150 feet long, ers' organization or crop improvement associa- spaced 12 or more inches apart. This increase tion. Sometimes foundation seed is distributed block then is observed very carefully at intervals directly to growers from the State agricultural throughout the growing season, and otft5^pe plants experiment station. P\H' new varieties or for old are eliminated. This method is much less time \arieties in short supply, requested amounts of consuming than the panicle-row method and ap- seed may be reduced in proportion to the amount pears to be quite satisfactory for well-established that is requested. varieties that have been purified several times previously. This method may be preferred to the Cleaning, Grading, and Processing Seed Rice panicle-row method, since there is less chance of Cleaning and processing seed rice is an exact- genetic alteration. ing operation that requires specialized equipment. A system that was inaugurated at Beaumont, Where conditions and facilities permit, it is de- Tex., in 1962 may eliminate growing breeder sirable to delay harvesting seed rice until the seed panicle rows of a variet}^ after a pure source moisture content is below 20 percent. If the com- of breeder seed is established. Under this sys- bine harvester is carefully adjusted, the rough tem the phint breeder produces a fairly large rice coming from ''clean" fields may be relatively quantity of seed from panicle rows or family free of stems, weed seeds, and trash so that it can blocks that is true to type for the variety. This be unloaded and safely elevated directlj^ into seed is cleaned and put into 50- to 100-pound aerated bins without prior aspirating or scalping. containers and is placed in storage under condi- In such case the seed rice is placed in hopper- tions suitable for maintaining the viability for bottom bins and aerated with an excess of air to at least 10 years. One or more units from stor- dry the grain or at least keep it from heating. age can be sown each succeeding year to produce Where necessary, the air may be heated to facili- foundation seed. tate drj^ing of the seed rice to a moisture level The advantage of this method is that once a sufficiently low for safe storage. If rice coming variety is purified, a continuing source of seed from the field contains considerable foreign ma- of known purity is available. To carry this sys- terial, it may be advisable to partly clean it with tem one additional step, a portion of the seed a scalper-aspirator machine before putting it in used to produce the seed for storage is saved and the bin for aeration. In some locations, facilities stored micler conditions suitable for retaining the and conditions require that the rough rice be viability for more than 25 years. Elach 5 to 10 dried before it can be safely stored. This dry- years, or as needed, a portion of this remnant ing may require that the rice be passed through seed may be sown to produce another supply of the drier several times. Frequently the rice is breeder seed identical to that originally stored. aspirated between passes to remove foreign mat- FOUND ATiox SEED PRODUCTION.—Foundation ter and light-weight, immature grains. Extreme seed usually is the first year increase from breeder care must be exercised to prevent mechanical seed. Foundation seed is produced on fields that mixing if the drying and cleaning facilities are have not grown another variety or a lower class used for more than one variety of rice. of the same variety during the 2 previous years. The first step in the cleaning and grading Preventing mixtures throughout the various process is to put the rice through a fanning mill, phases of seed production requires very close which has tlie following parts: (1) a wind aspi- attention when several varieties are handled with rator that removes light grain, hulls, and other the same equipment. To facilitate roguing of light-weight foreign material; (2) a screen with foundation seed fields, a space is left every few large perforations that removes any remaining feet by stopping up one or more of the holes in sticks, stems, mud lumps, or large weed seeds; the farm-type grain drill used for seeding. Such and (?)) a finely perforated screen that removes fields should be roguecl several times during the the finer broken rice grains, small weed seeds, last part of the growing season. Insofar as pos- and other small particles of foreign material. sible, foundation seed fields are managed to pro- It may be necessarj^ to put the rice through the duce satisfactory grain jàelds without excessive cleaner a second time to remove less easily sepa- vegetative growth and to minimize lodging. It rated material such as shelled rice grains and is impossible to satisfactorily rogue a field in weed seeds or an excess of light-weight, under- which an appreciable amount of lodging has developed grains. occurred. The next step is a grain-length separation that The release of foundation seed to growers may be accomplished either by a disk or an in- usually is handled through a committee or seed dented cylinder-type machine. Small pockets or council or similar organization that allots tlie indents in revolving disks or cylinders retain the seed to carefully selected growers, often on the shorter length grains (including broken grains basis of rice acreage within a county or parish. and hulled grains) slightly longer while the grain Sometimes the seed is turned over to a seed grow- is lifted by the revolving disk or cylinder, A 60 AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTtIRE special compartment collects and eliminates the for seed. The propagation of seed containing rejected material from the grain. long-grain red rice will soon result in a wide in- The third step in the cleaning and grading festation of the soil with long-grain red rice process is a diameter or width separation that strains and will further complicate the mainte- removes any large diameter rice grains, weed nance of pure seed production. seeds, or foreign materials. For this operation Following the diameter-grading operation, the either a vertical screen or a perforated cylinder seed rice usually is treated with a fungicide and grader is used. The grains of normal diameter often with an insecticide and placed in well- pass through the screen perforations while the marked 100-pound bags. The seed is then ready grains of larger diameter, the weed seeds, or for- for distribution to selected growers. eign materials are retained and thus removed Each of the rice experiment stations has a from the sample. For successful length and plant for processing seed rice. These plants are width separations, the sample should be free from designed to make the installations as nearly self- sticks, stems, and other foreign materials because cleaning as possible. They are being constantly such materials will interfere with the proper improved as new and improved equipment and functioning of the machine. methods are developed. Gravity movement of The length and diameter grading of seed rice bulk seed is used whenever possible. Steel or has been extremely useful in removnig the larger metal-lined bins with smooth walls and gravity diameter red rice grains from seed of long-grain flow metal hopper bottoms simplify cleaning varieties. The use of these graders has been the facilities. Belt conveyors are preferred to important in the control of red rice. In medium- other types because of ease of cleaning. and short-grain varieties, the only means of red The seed rice processing plant at Stuttgart, rice control is the use of red rice free seed and Ark., was described by Williams (86). It in- land, since no economical method of separation cludes a concrete dump pit, a truck hoist, a 6D- has as yet been devised. In some instances long- hundredweight-per-hour drier, two bucket-type grain red rice types have occurred in the long- elevators, ten 450-hundredweight bins, two half- grain varieties. Wlienever a lot of long-grain size working bins, cleaning equipment, a seed seed rice has a mixture of long-grain red rice, it treater, and 3,500 square feet of sack storage should be discarded immediately and not used space (fig. 27). In addition, seven 35-hundred- FiGUKE 27.—Rice seed processing plant at Stuttgart, Ark. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 61 weight bins are available for small lots of breeder other States lots of seed of this type must be seed. All bins are of steel construction and are reported. equipped with aeration. In order for the rice to be eligible for certifi- Small portable cleaning units without eleva- cation, the seed rice field must not have had an- tors or conveyors frequentlj^ are used for clean- other rice variety or the same variety of lower ing small lots of breeder seed. These small lots class growing on it the previous 2 years. The usually are dried on sack driers or small labora- field also must be isolated from other ricefields. tory driers to further reduce hazards of mixing. When the seed rice field is drill seeded, the mini- Various sizes and types of seed-cleaning and han- mum isolation distances range from 10 to 29 feet dling equipment are described in detail by Har- with a ditch, fence, roadway, or other definite mond, Klein, and Brandenburg (35), boundary. When the field is sown broadcast with ground equipment, the minimum isolation Standards for Seed Certification distance is 50 feet. When the adjoining field is seeded by airplane parallel to the seed rice field, The standards for field inspection and labora- the minimum isolation distance is 100 feet. When tory analysis of seed samples for seed certifica- adjoining fields are seeded by airplane at right tion are summarized in tables 17 and 18. These angles to the seed rice field, the minimum isola- reflect the ranges m the standards for the seed tion distance is one-fourth mile. In California, certification agencies in the Southern States of all ricefields that are to produce certified seed Arkansas (Arkansas State Plant Board), Loui- must be marked before April 15 at the corners siana (Louisiana Department of Agriculture and and at one-fourth-mile intervals by red or other Immigration), Mississippi (The Mississippi Seed vivid colored flags that are 3 feet square. Improvement Association), and Texas (The State Specific requirements and standards are estab- lished for each State and a list of these is avail- Seed and Plant Board, Texas Department of able from each of the ofiicial certifying agencies. Agriculture), and in California (California Crop In general, they are concerned with application Improvement Association). procedures, field and harvest inspection, post- In some States lots of seed that contain seed- harvest seed movement, seed processing, and ofii- transmissible diseases will not be certified, and in cial sampling. TABLE 17.—Banges a77iang inajor ricegroiDing States in standards for field inspection of rice for 1962 Standards for each class Factor Foundation Registered Certified Per acre Per acre Per acre Other varieties - definite 0 0 to IGO plants 10 to 200 plants. Other varieties — similar grain tvp^ 0 Up to 160 heads Up to 480 heads. Curly indigo and other highly objectionable v^eeds 0 0 0. Red rice 0 0 to 8 plants 0 to 18 plants. TABLE 18.—Ranges among ina'jor ricegroiving States in standards for cleaned seed of rice for 1962 Standards for each class Factor Foundation Registered Certified Pure seed (minimum) 98 to 99 percent 98 to 99 percent 98 to 99 percent. Other varieties - definite (maximum) 0 0 to 1 per 5 pounds 3 per 5 pounds to 5 per pound. Other varieties - doubtful (maximum) 0 to 7 per pound 0 to 10 per pound 0 to 20 per pound. Other crop seed (maximum) 0 to 1 per pound 1 to 2 per pound 2 to 5 per pound. Curly indigo, coffeebean, field bindweed 0 0 0. Other noxious weeds (maximum) 0 0 1 in pounds. Red rice (maximum) 0 0 to 1 per 2 pounds 0 to 1 per pound. Total weed seed (maximum) 0 to 0.05 per cent 0 to 0.1 percent 5 per pound to 0.1 percent. Inert matter (maximum) 1 to 2 percent 1 to 2 percent 1 to 2 percent. Germination (minimum) 80 to 85 percent 80 to 85 percent 80 to 85 percent. Moisture (maximum) 14 percent 14 percent 14 percent. 62 raOiiJLTTjRE HANDBOOK 2 8 9, U.S. DEPT, OF AGRICULTURE (IT) BEACHELL, H. M. Selected Refe 1943. EFFECT OF PHOTOPERIOD ON BICE VARIETIES GROWN IN THE FIELD. Jour. Agr. Res. 66: (1) ANONYMOUS. 325-340. 1960. GTJLFROSE ... A NEW KICE VARIETY RESIST- (18) ANT TO HOJA BLANCA DISEASE. TeX. Agl\ 1959. RICE. In Matz, S. A., ed., The Chemistry Expt. Sta. Leaflet 484, 4 pp. and Technology of Cereals as Food and (2) Feed, pp. 137-176. Avi Pub. Co., Inc., 1961. BELLE PATNA ... A NEW SHORT-SEASON, Westport, Conn. LONG-GRAIN RICE VARIETY. TeX. AgY. Expt. and HALICK, J. V. Sta. Leaflet L-512, 4 pp. (19) 1957. BREEDING FOB IMPROVED MILLING, PROCESSING (3) ADAIR, C. R. AND COOKING CHARACTERISTICS OF RICE. In- 1940. EFFECT OF TIME OF SEEDING ON YIELD, MILL- ternatl. Rice Comn. Newsletter 6(2) : 1-7. ING QUALITY, AND OTHER CHARACTERS IN RICE. Amer. Soc. Agron. Jour. 32: 697- (20) and HALICK, J. V. 1957. PROCESSING AND COOKING QUALITIES OF RICE 706. AND METHODS FOR THEIR DETERMINATION. (4) Presented Sixth meeting, Working Party 1941. INHERITANCE IN RICE OF REACTION TO HEL- on Rice Breeding, IRC, FAO, Vercelli, MINTHOSPORIUM ORYZAE AND CERCOSPORA ORYZAE. U.S. Dept. Agr. Tech. Bui. 772, 19 Italy, 9 pp. and JENNINGS, P. R. 19 pp. (21) 1961. MODE OF INHERITANCE OF HOJA BLANCA RE- and CRALLEY, E. M. (5) SISTANCE IN RICE. Rice Tech. Working 1950. 1949 RICE YIELD AND DISEASE CONTROL TESTS. Group Proc, pp. 11-12. Ark. Agr. Expt. Sta. Rpt. Ser. 15, 20 pp. (22) JoDON, N. E., JOHNSTON, T. H., and others. (6) and JONES, J. W. BREEDING RICE VARIETIES FOR RESISTANCE TO 1946. EFFECT OF ENVIRONMENT ON THE CHARACTER- 1959. THE VIRUS DISEASE HOJA BLANCA. Inter- ISTICS OF PLANTS SURVIVING IN BULK HYBRID natl. Rice Comn. Newsletter 8(3) : 6-9. POPULATIONS OF RICE. Amer. Soc. Agron. Jour. 38: 708-716. (23) SCOTT, J. E., EVATT, N. S., and others. 1961. BELLE PATNA. Rice Jour. 64(6) : 6-8, 24- (7) MILLER, M. D., and BEACHELL, H. M. 1962. RICE IMPROVEMENT AND CULTURE IN THE 26. UNITED STATES. Adv. in Agron. 14: 61- (24) BoRAsio, L., and GARIBOLDI, F. 108. 1957. ILLUSTRATED GLOSSARY OF RICE PROCESSING EQUIPMENT. FAO, Rome. (8) ANDERSON, A. L., HENRY, B. W., and TULLíS, E. C. 1947. FACTORS AFFECTING INFECTIVITY, SPREAD, AND (25) CHAMBLISS, C. E., and JENKINS, J. M. PERSISTENCE OF PIRICULARIA ORYZAE CAV. 1923. SOME NEW VARIETIES OF RICE. U.S. Dept. Phytopathology^ 37: 94-110. Agr. Dept. Bui. 1127, 17 pp. (9) ATEN, A., and FAUNCE, A. D. (26) CHILTON, S. J. P., and TULLíS, E. C. 1953. EQUIPMENT FOR THE PROCESSING OF RICE. 1946. A NEW RACE OF CERCOSPORA ORYZAE IN RICE. FAO Devlpmt. Paper 27, 55 pp. Phytopathology 36: 950-952. (10) ATKINS, J. G., and ADAIR, C. R. (27) CRALLEY, E. M. 1957. RECENT DISCOVERY OF HOJA BLANCA, A NEW 1949. WHITE TIP OF RICE. (Abstract) Phyto- RICE DISEASE IN FLORIDA, AND VARIETAL RE- pathology 39: 5. SISTANCE TESTS IN CUBA AND VENEZUELA. (28) CRANE, L. E. Plant Dis. Rptr. 41: 911-915. 1959. NEW RICE VARIETY, "GULFROSE," INTRODUCED. (11) — BEACHELL, H. M., and CRANE, L. E. Rice Jour. 62(13) : 2-3, 17. 1956. REACTION OF RICE VARIETIES TO STRAIGHT- (29) DAVIS, L. L. HEAD. Tex. Agr. Expt. Sta. Prog. Rpt. 1950. CALIFORNIA RICE PRODUCTION. Calif. Agr. 1865, 2 pp. Ext. Ser. Cir. 163, 55 pp. (12) BEACHELL, H. M., and CRANE, L. E. (30) FRAPS, G. S. 1957. TESTING AND BREEDING AMERICAN RICE VARI- 1916. THE COMPOSITION OF RICE AND ITS BY-PROD- ETIES FOR RESISTANCE TO STRAIGHTHEAD. UCTS. Tex. Agr. Expt. Sta. Bui. 191, 41 pp. Internatl. Rice Comn. Newsletter 6(2) : (31) GEDDES, W. F. 12-15. 1951. RICE. MILLING. In Jacobs, M. B., ed.. The (13) BoLLiCH, C. N., JOHNSTON, T. H., and others. Chemistry and Technology of Food and 1963. BREEDING FOR BLAST RESISTANCE IN THE Feed Products. 3 v. Interscience Pub., UNITED STATES. Blast Symp. Proc, Inter- Inc., New York. natl. Rice Res. Inst., Los Banos, Philip- (32) HALICK, J. V., BEACHELL, H. M., STANSEL, J. W., pines. July. and KRAMER, H. H. (14) and JoDON, N. E. 1960. A NOTE ON THE DETERMINATION OF GELATINI- 1963. ASPECTS OF BREEDING RICE FOR RESISTANCE ZATION TEMPERATURES OF RICE VARIETIES. TO DISEASES, PARTICULARLY BLAST (PIRICU- Cereal Chem. 37 : 670-672. LARIA ORYZAE). Internatl. Rice Comn. (33) and KELLY, V. J. Newsletter, Spec, issue, 10th Pacific Sei. 1959. GELATINIZATION AND PASTING CHARACTERIS- Cong. Symp., pp. 41-52. TICS OF RICE VARIETIES AS RELATED TO COOK- (15) and TODD, E. H. ING BEHAVIOR. Cereal Chem. 36: 91-97. 1959. WHITE TIP DISEASE OF RICE. IH. YIELD (34) and KENEASTER, K. K. TESTS AND VARIETAL RESISTANCE. Phyto- 1956. THE USE OF A STARCH-IODINE-BLUE TEST AS A pathology 49 : 189-19L (16) QUALITY INDICATOR OF WHITE MILLED RICE. AuTREY, H. S., GRIGORIEFF, W. W., ALTSCHUL, A M Cereal Chem. 33 : 315-319. and HoGAN, J. T. (35) HARMOND, J. E., KXEIN, L. M., and BRANDENBURG, 1955. RICE MILLING EFFECTS OF MILLING CONDI- N. R. TIONS ON BREAKAGE OF RICE GRAINS. Jour. 1961. SEED CLEANING AND HANDLING. U.S. Dept. Agr. and Food Chem. 3 : 593-599. Agr., Agr. Handb. 179, 38 pp. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 63 (36) INTERNATIONAL CKOP IMPROVEMENT ASSOCIATION. (55) 1959. MINIMUM SEED CERTIFICATION STANDARDS. 1936. IMPROVEMENT IN RICE. U.S. Dept. Agr. Pub. 19, 111 pp. Chambers Printing Co., Yearbook 1936: 415-Í54. Clemson, S.C. (56) (37) JENKINS, J. M. 1938. THE ''ALKALI TEST" AS A QUALITY INDICATOR 1936. EFFECT OF DATE OF SEEDING ON THE LENCITH OF MILLED RICE. Amer. Soc. Agron. Jour. OF THE GROWING PERIOD OF KICE. La Agi" 30: 960-967. Expt Sta. Bui. 277, 7 pp. (57) ADAIR, C. R., BEACHELL, H. M., and others. (38) and JONES, J. W. 1953. RICE VARIETIES AND THEIR YIELDS IN THE 1944. RESULTS OF EXPERIMENTS WITH RICE IN UNITED STATES 1939-50. U.S. Dept. Agr. LOUISIANA. La. Agr. Expt. Sta. Bui. 384, Cir. 915, 29 pp. 39 pp. (58) JENKINS, J. M., NELSON, M., and others. (89) JODON, N. E. 1941. KICE VARIETIES AND THEIR COMPARATIVE 1938. EXPERIMENTS ON ARTIFICIAL HYBRIDIZATION Y^IELDS IN THE UNITED STATES. U.S. Dept. OF RICE. Ajuer. Soc. Agron. Jour. 30: 294- Agr. Cir. 612, 34 pp. 305. (59) JENKINS, J. M., WYCHE, R. H., and NELSON, (40) M. 1953. GROWING PERIOD OF LEADING RICE VARIETIES 1938. RICE CULTURE IN THE SOUTHERN STATES. WHEN SOWN ON DIFFERENT DATES. La. Agr. U.S. Dept. Agr. Farmers' Bui. 1808, 29 pp. Expt. Sta. Bui. 476, S pp. (60) KARON, M. L., and ADAMS, MABELLE E. (41) 1949. HYGROSCOPIC EQUILIBRIUM OF RICE AND RICE 1955. IMPROVING VARIETIES OF RICE AND SORGHUM. FRACTIONS. Cereal Chem. 26: 1-12. 47th Ann. Prog. Rpt., La. Rice Expt. Sta., (61) KESTER, E. B. pp. 83-87. 1959. RICE PROCESSING. In Matz, S. A., ed., The (42) Chemistry and Technology of Cereals as 1955. SUNBONNET AND TORO. 2 NEW MIDSEASON Food and Feed, pp. 427-461. Avi Pub. LONG-GRAIN RICE VARIETIES. La. Agr. Expt. Co., Inc., Westport, Conn. Sta. Bui. 499, 12 pp. (62) KiK, M. C, and WILLIAMS, R. R. (48) 1945. THE NUTRITIONAL IMPROVEMENT OF WHITE 1957. NATO. AN EARLY MEDIUM-GRAIN RICE. La. RICE. Nati, Res. Council Bui. 112, 76 pp. Agr. Expt. sta. Cir. 47, 14 pp. (63) KING, B. M. (44) 1937. THE UTILIZATION OF WABASH CLAY ( GUMBO ) 1961. PERFORMANCE OF RICE VARIETIES IN 1961. SOILS IN CROP PRODUCTION. Mo. Agr. Expt. 53rd Ajin. Prog. Rpt., La. Rice Expt. Sta., Sta. Res. Bui. 254, 42 pp. 162 pp. [Processed.] (64) LATTERELL, FRANCES M., TULLíS, E. C, and COLLIER, (45) and CHILTON, S. J. P. J. W. 1946. SOME CHARACTERS INHERITED INDEPEND- 1960. PHYSIOLOGICAL RACES OF PIRICULARIA ORY- ENTLY OF REACTION TO PHYSIOLOGIC RACES ZAE CAv. Plant Dis. Rptr. 44: 679-683. OF CERCOSPORA ORY^ZAE IN RICE. Amer. SoC. (65) LITTLE, RUBY R., HLLDER, GRACE B., and DAWSON, Agron. Jour. 38 : 864-872. ELSIE H. (46) and DE LA HOUSSAYE, D. A. 1958. DIFFERENTIAL EFFECT OF DILUTE ALKALI ON 1949. RICE VARIETIES FOR LOUISIANA. La. AgV. 25 VARIETIES OF MILLED WHITE RICE. Cereal Expt Sta. Bui. 436, 15 pp. Chem. 35: 111-126. (47) RYKER, T. C, CHLLTON, S. and J. P. (66) NAGAI, I. 1944. INHERITANCE OF REACTION TO PHYSIOLOGIC 1959. JAPÓNICA RICE. ITS BREEDING AND CULTURE. RACES OF CERCOSPORA ORYZAE IN RICE. Amer. 843 pp. Yokendo Ltd., Tokyo. Soc. Agron. Jour. 36 : 497-507. (67) NELSON, M., and ADALR, C. R. (48) JOHNSTON, T. H. 1940. RICE VARIETY EXPERIMENTS IN ARKANSAS. 1958. REGISTRATION OF RICE VARIETIES. AgroD. Ark. Agr. Expt. Sta. Bui. 403, 28 pp. Jour. 50: 694-700. (68) ORMROD, D. P., and BUNTER, W. A., JR. (49) ADAIR, C. R., TEMPLETON, G. E., and others. 1961. THE EVALUATION OF RICE VARIETIES FOR COLD 1963. NOVA AND VECIOLD . . . NEW RICE VARIETIES. WATER TOLERANCE. AgroD. Jour. 53: 133- Ark. Agr. Expt. Sta. Bui. 675, 23 pp. 134. (50) and CRALLEY, E. M. POEHLMAN, J. M. 1955. RICE VARIETIES AND THEIR YIELDS IN ARKAN- (69) SAS, 1948-1954. Ark. Agr. Expt. Sta. Rpt. 1959. BREEDING BICE. VARIETAL HISTORY OF RICE Ser. 49, 20 pp. IN THE UNITED STATES. His Breeding Field (51) CRALLEY, E. M., and HENRY, S. E. Crops, pp. 174-189. Henry Holt and Co., 1959. PERFORMANCE OF RICE VARIETIES IN ARKAN- Inc., New York. SAS, 1953-1958. Ark. Agr. Expt. Sta. Rpt. (70) RAMIAH, K. Ser. 85, 31 pp. 1933. INHERITANCE OF FLOWERING DURATION IN (52) TEMPLETON, G. E., WELLS, J. P., and HENRY, RICE (ORYZA SATIVA L. ). Indian Jour. Agr. S. E. Sei. 3: 377^10. 1962. NORTHROSE, A NEW SPECIAL-PURPOSE RICE (71) RAO, B. S., VASUDEVA MURTHY, A. R., and SUBBAH- VARIETY FOR ARKANSAS. Rice Jour. 65(8) : MANYA, R. S. 10, 12-14, 18^19. 1952. THE AMYTLOSE AND THE AMYXOPECTIN CON- (53) TEMPLETON, G. E., WELLS, J. P., and HENRY, TENTS OF RICE AND THEIR INFLUENCE ON S. E. THE COOKING QUALITY OF THE CEREAL. In- 1962. NORTHROSE RICE—A SPECIAL-PURPOSE, STIFF- dian Acad. Sei. Proc. 36B : 70-80. STRAWED EARLY VARIETY FOR ARKANSAS. (72) REYNOLDS, E. B. Ark. Farm Res. 11(2) : 2. 1954. RESEARCH ON RICE PRODUCTION IN TEXAS. (54) JONES, J. W. Tex. Agr. Expt. Sta. Bui. 775, 29 pp. 1923. RICE EXPERIMENTS AT THE BIGGS RICE FIELD (73) RYKER, T. C. STATION IN CALIFORNIA. U.S. Dept. Agr. 1943. PHYSIOLOGIC SPECIALIZATION IN CERCOSPORA Dept. Bui. 1155, 60 pp. ORYZAE. Phytopathology 33 : 70-74. 64 \j;la f í/iüKE JIANDBOOK L*89, U.S. DEP1\ OF AGRICULTURE (74) KYKEK , T. ( \ USE OF THE SIZING DEVICE. Rice Jour 1947. NEW PATHOGENIC RACES i)V CEKCOSTOKA ORY- 58(12) : 9. ZAE AEFECTING RICE. (AltStmCtl IMlVto- (82) ToDD, E. IT., and IîEACHELL, H. M. patholo^ry 37 : 1S)~'1(). 1954. STRAIGHTHEAD OF RICE AS INFLUENCED BY (75) and CowART, L. E. VARIETY AND IRRIGATION PRACTICES. TEX. 1948. DEVELOPMENT OF CERCOSPOR A-RESIST A NT Agr. Expt. Sta. Prog. Rpt. 1650, 3 pp. STRAINS OP RICE. (Abstract) Phytopathol- (83) WARTH, F. J., and DARABSETT, D. B. ogy 38: 23. 1914. THE FRACTIONAL LIQUEFACTION OF RICE (76) SCOTT, J. E., WEBB, B. D., and BEACHELL, H. M. STARCH. Mem. Dept. Agr. India, Chem 1964. RICE TEST-TUBE MILLER. CrOp Sci. "Brief Ser. 3 : 135-147. Articles" 4: 1231. (84) WAYNE, T. B. I(71 < < ;\ WEBB, B. D., and BEAGHELL, II. M. 1930. MODERN RICE MILLING AS PRACTICED IN THE 1964. SMALL SAMPLE RICE POLISHING MACHINE. WORLD'S LARGEST COMPLETE MILL. FoOlJ Crop Sei. "Brief Articles" 4: L'32. Indus. 2 : 492-495. (78) SMITH, W. D. (85) WELLS, D. G., and CAFFEY, H. R. 1955. THE USE OF THE CARTER DOCKAGE TESTER TO 1956. SCISSOR EMASCULATION OF W^HEAT AND BAR- REMO\^ WEED SEEDS AND OTHER FOREIGN LEY. Agron. Jour. 48 : 496-499. MATERIAL FROM ROlXiH RICE. KiCC Joiir. (86) WILLIAMS, F. J. 58(9) : 26-27. 1957. AT THE RICE BRANCH EXPERIMENT STATION (79) ... A NEW^ SEED PROCESSING PLANT. Ark 1955. THE USE OF THE M CG ILL SHELLER FOR RE- Farm Res. 6(5) : 2. MOVING HC^LS FROM ROT^GH RICE. Kico (87) WILLIAMS, V. R., Wu, W. T., TSAI, H. Y., and Jour. 58 ( KJ ) : 20. BATES, H. G. (80) 1958. VARIETAL DIFFERENCES IN AM Y LOSE CONTENT 1955. THE USE OF THE MCGILL MILLER FOR MILL- OF RICE STARCH. Agr. Food Chem. 6(1) : ING SAMPLES OF RICE. Rice Jour. 58(11) : 47-48. 20. (88) WISE, L N. (81) 1954. RESEARCH IN SEED PROCESSING. Amer. Soc. 1955. THE DETERMINATION OF THE ESTIMATE OF Agron. 1954 Annual Meetings Agron. Abs., HEAD RICE AND OF TOTAL YIELD WITH THE p. 91. SOILS AND FERTILIZERS By D. S. MiKKELsKN and N. S. EVATT Types of Soils Used for Rice Production Rice, a semiaquatic plant, must be maintained Because rice can grow in flooded soils, it is oc- under flooded conditions during part or all of casiomilly used as a reclamation crop. Varie- the growing season to minimize weed competition ties difl'er in tolerance to salinity, but all are and to provide high jnelds. Because of these aftected by the salt concentration of the soil so- water recpiirements, the ideal soil types for rice lution in the root zone. The effects of salinitj^ production are those that conserve water. Usu- on rice depend somewhat on its stage of devel- ally clay and clay loams, silty clay loams, or silt opment when it is exposed to saline conditions. loams are considered most desirable. Soils with Studies of salinity effects indicate that rice is a high clay and silt content provide conditions most tolerant during germination and is most for sloAv water percolation. Other soils, includ- sensitive during the 1- to 2-leaf stage. Salt tol- ing organic soils, can be used if they possess a erance apparentl}^ increases during the tillering hardpan or claj^pan capable of maintaining up to and elongation stages Ijut decreases during the 8 inches of floodwater. Eice soils sliould be capa- flowering stage. Results of field experiments ble of easy surface drainage also, since many have indicated that high soil salinity occurring aspects of mechanization require removal of the at planting time may seriously impair yield by surface water. reducing germination and stand establishment. Apart from the aspects of water conservation, Most rice soils, often referred to as heavy soils light-textured clay and silt soils are generally because of their high clay and silt content, pre- preferred because of their generally favorable sent special management problems. These in- fertility and chemical and physical properties clude tillage and seedbed prepjaration, mainte- conducive to the satisfactory growth of rice. nance of organic matter and soil structure, These soils, when drained, adequately supjHjrt the adequate drainage for essential mechanized rice mechanical equipment used in rice production. operations and for other crops planted in rota- Soil requirements for rice are not demandnig, tion, green manure crops, fertilizer application, but the soil should be fertile and capable of sat- and weed control. Management of rice soils is isfactory management. discussed in the section ''Culture," p. T-I-. Eice does not have a critical soil pH require- The soils most widely used in rice production ment, although the best pn'oducing soils have val- in tlie United States are of alluvial origin (33)} ues between 5.5 and 6.5. In this range of pH Brief descriptions of the soils used for rice in values, nutrient availability is generally good; the principal rice-growing States are given be- and toxicities from such things as aluminum, low. iron, Sulfides, and sodium do not generall)^ occur. The soil pH in the rice root zone normally in- Arkansas creases from 0.5 to 1.5 pH units when placed Crowlej" silt loam, Callioun silt loam, and under flooded conditions, and it decreases when Sharkey clay are the principal soils used for rice the excess water is removed. This increase of production in Arkansas {31}. Other soils are pH influences the uptake of nutrients and plant sometimes used. development. Use of some fertilizers, particu- CROWLEY SILT LOAM.^TIIC surface of Crowley larly prolonged use of ammonium nitrogen silt loam is gray to brown. It is underlain with sources, increases soil acidity. It is not uncom- a gray or yellowish-gray silt loam that changes mon for soil pH to decrease as mucli as 2 pH with depth into a gray silty clay and finally into units where ammonium nitrogen sources have a heavy clay usually mottled with yellow and been used in rice production for 15 to 20 years. red. CroAvle)^ silt loam in its virgin state has a Salinity problems are sometimes encountered fairlv liiirh or^'anic nnatter content, but it is low in areas where soluble salts have accumulated or in phosphorus and is strongly acid. where a poor quality of irrigation water is used. CALHOUX SILT LOAM.—Calhoun silt loam is a Sea water that is intruded into rivers and wa- terways or that is brought in by storms of hur- 1 ItaUc iiumbei-8 in parentheses refer to Selected Refer- ricane force may be a source of excess salinity. eiH'es, p. Tu. 65 66 í'liUH IIANDIKHJK 289, IJ.8. DEPT. OF A(ÍRICULTURE light gray to almost white sriallow soil iinder- Texas Wm with a compact dral) or Yelh)wisri-(lrab clay. In addition to Beaumont clay soil wdiich com- This soil is common in lowlands in easterii Ar- prises about one-fourth of the riceland in Texas, kansas. Calhonn silt loam is low in total nitro- rice is growai on Lake Qiarles clay, Bernard gen and phosphorns, and it is acid to strongly clay loam, Edna fine sandy loam, Hockley fine acid. Eice is commonly grown on Calhoun silt sandy loam, and Katy fine sandy loam (38). loam in the ''North-end" of the Arkansas rice LAKE CHARLES CLAY.—Lake Charles clay is area. the principal heavy soil in the rice belt west of SííARKEY CLAY.—The snrface soil of Sharkey the Trinity River 'in Texas. It comprises prob- clay is a dark, drab, or grayish-brown silty clay ably one-third to one-half of the rice acreage usually mottled with l)rown. Tliis is underlain around Houston, Angleton, Bay City, and El at varying depths with a drab, steel-gray or blue, Campo. Lake Charles clay is darker and more sticky' clay. Sand is frequently found in the granular than Beaumont clay. It is slightly acid surface layer. Sharkey clay occurs commonly in to mildly alkaline in reaction, with a pH of the Mississippi River'bottoms. It is known as 6 to 8. "buckshot land" because it granulates and forms BERNARD CLAY^ LOAM.—Bernard clay loam is a crumb structure. It can be plowed when w^et; similar to Lake Charles clay but is more loamy and as it dries out, it breaks down into granules and slightly less dark, and it occurs on slightly or into clods that are easily slaked by rain. higher elevations. It is found both east and west Under mitural conditions this soil is poorly of the Trinity River in Texas. This soil is drained, and the natural A^egetation is hardwood slightly acid to neutral in reaction, w^ith a pH and cypress. In the virgin state it is well sup- of 6 to 7. plied with nitrogen and phosphorus, and it is EDNA FINE SANDY^ LOAM.—Edna fine sandy slightly acid to neutral in reaction. In recent loam has a grayish, sandy surface and is under- years, Sharkey clay has been widely used for rice lain at a depth of 6 to 12 inches by a heavy, gray in the Mississippi Valley. clay pan. It is found principally in the western OTHER SOILS.—Other soils sometimes used for and southwestern parts of the Texas rice belt. rice production in Arkansas are AVaverly silt IIocKLEY FINE SANDY LOAM.—The Hockley loam, and Waverly, Miller, and Portland clay soils form a narrow belt along the northern part soils. Because these soils usually have poor nat- of the rice area from Cleveland, in Liberty ural drainage, they have come into use for rice County, westward through Hockley, Sealy, and production only in recent years. Eagle Lake to western Victoria County, Texas. These sandy loam soils are underlain by friable, Louisiana sandy clay subsoils. They are slightly more According to Walker and Miears (55), the sloping and better drained than are the Katy principal soils used for rice production in Loui- soils, and they require more irrigation water siana are the Crowley, Midland, and Beaumont than do the Katy soils. soils. KATY- FINE SANDY LOAM.—Katy fine sandy CROW^LEY SOILS.^—Soils of this type found in loam occurs in large level areas adjacent to Lake Louisiana are the same as soils of this type in Charles soils and in the flatter portion between Arkansas. the slightly more sloping and better drained MIDLAND SOILS.—The Midland soils, which gen- Hockley soils. erally are alluvium deposited by the Red and the California Mississippi Rivers, are deep and poorly drained (5). The surface soil is gray to dark gray and Stockton and Sacramento clay (27) and Wil- strongly acid. The subsoil is strong-brown to lows (14) are the principal soils used for rice light olive-browm, heavy, silty clay mottled with production in California. However, several other gray. It is very strongly acid to mildly alkaline. soils are also used. MIDLAND-CROWLEY ^IIXED SOILS.—Soils that STOCKTON SOILS.—Stockton adobe clay is one are a mixture of Midland silt loam. Midland of the principal soils used for rice culture in silty clay loam, and Crowdey silt loam are used California. The surface soil is dark-gray or for rice in Louisiana. Fertility and organic mat- black clay, 5 to 16 inches deep. When w^et, it is ter content of the soils are moderate, and surface dense and plastic, but it shrinks in drying and runoff, infiltration, and permeability are slow (5). develops large blocks separated by wide cracks. The upper part of the dark, grayish-browai, heavy BEAUMONT CLAY\—Beaumont clay soil is acid, clay subsoil is similar in structure and consist- poorly drained, and very slowly permeable (38). ency to the surface soil but is calcareous. The It occurs mainly in southw^est Louisiana and in subsoil has slightly more colloidal clay and less Texas, east of the Trinity River. organic matter than the surface soil. RICE IN THE UNITED STATES : VxVKlETIES AND PRODUCTION 67 SACRAMENTO SOLLS.—Sacramento clay soil oc- working with naturally flooded soils and lake cupies low-lying flood plains and is derived from muds, determined that there were significant dif- transported material of mixed geological origin. ferences l)etween the soil at the soil-water inter- It was developed under poorly drained, marshy face and the soil inmiediately beneath. Plood- conditions. The dark-gray or dark, brownish- water containing some dissolved oxygen main- gray surface soil, 14 to 24 inches deep, is coarse tained a thin surface layer of soil in an oxidative and lumpy. It is heavy textured, and contains condition with soil color characteristics and varying quantities of completely or partly de- pliysico-chemical and biological properties dif- cayed organic matter. The transition to a vari- ferent from those of the soil beneath. Oxidation- able subsoil, made up of stratified layers of min- reduction potentials in the oxidative layer ex- eral and organic soil material, is rather abrupt. ceeded 3i>0 to 350 millivolts at a pTI of 5.0 and WILLOWS SOLLS.—Willow soils consist of stream contained such oxidized chemical radicals as sediment, usually reddish or j^ellowish brown or nitrates, sulfates, ferric, and manganic ions. The dark brown, deposited along the courses of minor underlying soil was conspicuous by the absence creeks or in the waters of temporary lakes, and of oxygen and the concomitant presence of the underlain by brown to light-brown, compact and reduced forms of chemical radicals such as am- relatively impervious subsoils. monium, ferrous iron, and manganous manga- OTHER SOILS.—Other California soils fre- nese; nitrogen gas and its oxides; and various quently used for rice production include Gene- Sulfides, including hydrogen sulfide. The oxida- vera, Meyers, and Yolo of sedimentary alluvial tion potentials were generally below 350 milli- origin; Marvin, Merced, and Sycamore of mixed volts at a pH of 5.0 in the reclucing layer. Mik- alluvial origin; and San Joaquin of granitic al- kelsen and Finfrock (17) showed that reducing luvial origin. conditions in Stockton clay develop about 3 days after a soil is flooded. Patrick and Sturgis (23) Chemistry of Flooded Soils showed that when soils are flooded, the soil oxy- gen disappears within a few hours and may be In the production of rice, the benefits of flood- nearly absent at depths exceeding about one-half ing the soil are recognized wherever the crop is inch. grown. Senewiratne and Mikkelsen (29) re- The oxidation-reduction status of the soil un- viewed the literature and provided evidence that der flooded conditions is governed by several flooding enhances foliar development, tillering, factors, including the rate of oxygen exchange, and earlier flowering and increases yield of rice microbial activity, the soil content of decompos- when compared with nonflooding irrigated cul- able organic matter, and the base saturation ture. The superior growth of rice under flooded status. conditions can be attributed in part to the eftects Flooding has been shown to increase the soil of the acjuatic environment ; but the chemical pH. The increase depends partly on the initial characteristics of flooded soils are of major im- pH value and organic matter content of the soil, portance in the development of the crop. and on the period of submergence. The pH in- The most distinguishing characteristic of a crease varies usually between 0.5 and 1.5 pH flooded soil is the presence of standing water units. Reed and Sturgis (26) showed that the during part or all of the growing season. The pH increase in flooded soils they studied varied layer of flooclwater, creating waterlogged con- from 0.82 to 1.55 pH units, depending on soil ditions, exerts profound changes in the physical, conditions and initial pH values. Generally, soils chemical, and biological status of the soil. The with a low pH and with high soil organic matter immediate effect of flooding is a drastic curtail- composition undergo the greatest pH changes ment of gaseous exchange between the atmosphere when flooded. The cause of the pH increase is and the soil. Water fills the soil pores, reducing not completely understood but has been attrib- oxygen entry and often allowing accumulation of uted variously to increased ammonium compo- gaseous products of anaerobic decomposition. sition, soluble ferrous, and manganous hydrox- Carbon dioxide concentrations build up in the ides, which neutralize the exchangeable hydrogen ions in the soil. flooded soils, together with methane, hydrogen, Another generally observed result of flooding nitrogen, and various oxides of nitrogen. is the increased specific conductance of the soil Entry of oxygen is not completely restricted solution. The phenomenon is well established, but is confined largely to a thin layer of soil at but detailed information is lacking on the spe- the soil-water interface (23). Oxygen arises cific nature of the increased composition of dis- from gaseous exchange with the atmosphere and solved solids in the soil. The increase in the as a product of photosynthesis of phytoplankton concentration of ammonium, iron, and manga- and hydrophytes. nese ions, and in the bases displaced by these Pearsall (24) and Pearsall and Mortimer (^5), ions from the soil exchange complex may in part 68 AiUuCULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE account for the increased specific conductance. resistant materials, high in lignin, decomposition The increased composition of carbon dioxide, under flooded conditions is delayed to a much especially at high pH values, would increase the greater extent. In well-drained soils, the end bicarbonate ion concentration. products of organic matter decomposition are Several mechanical properties of soils, includ- principally carbon dioxide, nitrates, and sul- ing permeability, plasticity, cohesion, and consist- phates. Under flooded conditions, the end prod- ency, are changed by flooding. Ordinarily, these ucts include methane, hydrogen, various organic changes do not adversely influence the growth of acids, ammonium ions, nitrogen and its various rice. Allison [£) showed that the permeability oxides, amines, mercaptans, and hydrogen sulfides. of a flooded soil is influenced by the amount of The rate of organic matter decomposition in air entrapped during submergence. He noted soils depends on the kind of organic constituents that permeability decreased after flooding but and their nitrogen content and the carbon-nitro- increased again as air trapped in the soil was gen ratio. Ordinarily, if nitrogen is adequate released. At a later period after flooding, per- for microbial function, nitrogen is mineralized, meability may again decrease if bacteria-pro- and if carbonaceous materials are in excess, nitro- duced material blocks the pores and restricts wa- gen is immobilized. Data from various sources ter movement. indicate that organic matter decomposition under Sturgis {31) called attention to possible dele- anaerobic conditions proceeds at lower total nitro- terious effects of flooding on soil structure. He gen values than the 1.2- to 1.5-percent nitrogen cited evidence that low productivity of some values established under aerobic conditions and Louisiana soils was caused by deflocculation dur- that immobilization of nitrogen does not occur ing flooding. The specific factors associated with except at higher carbon-nitrogen values than the the deflocculation were not reported. approximate 15:1 established for well-drained In addition to other effects, flooding has an soils. In well-aerated soils, the mineralization of important influence on soil temperature and con- organic matter gradually increases nitrate pro- sequently affects the growth of rice both directly duction. In flooded soils, the mineralization proc- and indirectly. The high specific heat and high ess produces ammonium ions. The number of heat of vaporization of water prevent its tem- ammonium ions reaches a plateau value rather perature from dropping as fast or as low as does rapidly and then declines rather sharply. air temperature. Under some circumstances, this The occurrence of two distinct layers—an oxi- modification of the plant environment may en- dative layer at the soil-water interface and a re- hance the growth of rice. duction layer immediately beneath—exerts a sig- Upland soils with good aeration usually main- nificant influence on agronomic factors associated tain diverse populations of microflora and micro- with rice production. These layers should be fauna. These organisms decompose organic mat- taken into account in seedbed preparation, crop ter from which they derive energ)^ and liberate residue management, fertilization, cultivation, and carbon dioxide. They exert a heavy demand for water management. nutrients, especially nitrogen, as they produce Two types of nitrogen transformations occur in cellular material. Under flooded conditions, the flooded soils, depending on whether oxidizing or normal soil complement of actinomycetes, fungi, reducing conditions prevail. In the thin oxidiz- bacteria, algae, and protozoa is modified to pro- ing layer at the surface, the nitrogen transforma- duce a microflora consisting principally of anaer- tions are similar to those that occur in well- obic bacteria, some facultative anaerobes, and a drained soils. Organic matter in this layer is modified population of algae. The anaerobic mineralized to ammonium ions and ultimately to forms have a much lower energy requirement nitrate ions by the action of highly specialized than do the aerobic forms and consequently de- autotropic micro-organisms. The nitrate ions are compose organic matter at a slower rate. The used by either plants or micro-organisms. They slower decomposition of organic matter under may be immobilized, depending on the carbon- flooded conditions is partly responsible for the nitrogen ratio of the organic matter; or they may development of peat in bogs and marshes. The be moved into the underlying reducing zone by modification in the soil microflora and micro- leaching. The nitrogen status of the reducing fauna is only temporary, and normal populations zone is characterized by the denitrification of develop when drainage and aeration are main- nitrates and the accumulation of ammonium ions. tained. The ammonium ions that are produced by the The decomposition of organic matter proceeds more sluggish bacterial microflora are not re- at a slower rate in flooded soils than in upland duced and provide the reservoir of nitrogen for soils, and the end products are different. Tenney use by the rice crop. Nitrates that move into or and Waksman (33) showed that the decomposi- originate in this layer are reduced to nitrites and tion of cornstalks under flooded conditions pro- fhially to nitrogen gas or its oxides. These gases ceeds at about half the usual rate; and with more ultimately escape into the air. This reduction of RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 69 nitrates is favored by low oxygen tensions and the posable organic matter in the soil enhances the presence of oxidizable organic matter. Janssen reduction process. With sustained flooding, equil- and Metzger {10) have amply demonstrated that ibriuni develops between the soil and the soil nitrate nitrogen accumulates in well-drained soils, solution, with a significant increase in soluble in contrast with flooded soils wliere ammonium and exchangeable iron. Both mineral and organic ions accumulate. salts of iron appear in the soil solution. Ordinar- The practical significance of the dilïerentiation ily, the abundance of soluble iron does not ad- of distinct oxidation and reduction layers is ap- versely aftect the growth of rice; but situations parent in results demonstrating the poor efRciency may exist where toxicities or nutrient antagonism of nitrate-nitrogen fertilizer sources in continu- may impair growth. ously flooded soil and the desirability of fertilizer Manganese chemistry of the soil is not well placement of ammonium nitrogen sources {20). understood. Its forms are dynamic in equilib- Nitrate nitrogen that is applied as a basal ferti- rium, depending on such factors as pH, oxidation- Hzer application or that develops in the oxidation reduction status, the presence of organic matter, layer is largely lost through leaching and subse- and microbial activity. Manganese occurs in quent denitrification. Where reducing conditions three valence forms, with some compounds con- develop after flooding, drilling ammonium nitro- taining manganese in two valence forms. In some gen several inches into the soil before flooding respects, the behavior of manganese in the soil is provides good retention and availability of the similar to that of iron. In flooded soils, the high- nitrogen for the rice crop [17). er oxides of manganese are reduced to soluble and Flooding a soil often provides conditions for exchangeable ions. Biological reduction occurs the increased availability of both the native phos- independent of soil pH if low oxidation-reduction phonis and that applied as fertilizer. Evidence potentials exist. Decomposing organic matter re- of this is obtained in both the uptake of phos- duces manganese, especially in the lower soil pH phorus by rice and the increased solubility of range. It is unusual for soil manganese in flooded phosphorus, as shown by soil-test extraction meth- soils to afl'ect growth of rice adversely. High ods (i-i. 20, 30). Factors that appear to be asso- levels of soluble and exchangeable manganese in ciated with increased phosphoras availability the soil may be toxic to sensitive crops grown in include pH modification, reduction of insoluble rotation after rice. ferric phosphate to the more soluble ferrous form, hydration and subsequently increased hydrolysis Fertilizers of ferric and aluminum phosphates, and increased displacement of soluble phosphorus by formation Southern Rice Area of complex ion and substitution of organic anion. Sulfur in organic forms or as the sulfate ion is The proper use of fertilizers on rice increases ultimately reduced, at least in part, to sulfides in yield from 30 to 50 percent in the southern rice flooded soils. Sulfate reduction is accomplished area. Practically the entire rice area in Louisiana by anaerobic bacteria that are active over a wide and Texas requires additions of commercial fer- range of soil pH and operate under low oxidation- tilizers for economical yields. This is also tiaie reduction potentials. Hydrogen sulfide, the end with most of the rice soils in Arkansas, particu- product of bacterial reduction, may occur free in larly in the traditional ricegrowing area of the gases produced in flooded soils and may accumu- Grand Prairie region; however, the newer rice late in amounts toxic to rice. This occasionally bottomland soils in the delta areas of Arkansas occurs in light-textured soils under extreme re- and Mississippi may not require fertilizer during ducing conditions and in the presence of large the first year or two of rice cropping. amounts of readily decomposable organic matter. Commercial fertilizers were not used exten- Normally, soils contain sufficient active iron to sively in the southern rice area before World War completely precipitate the sulfide ion as ferrous II. In fact, results from many of the soil fertil- sulfide. ity tests conducted in the early thirties showed Iron, a prominent constituent of the soil, occurs negative yield responses from fertilizer applica- tions {12). This was usually true when various in primary minerals, hydrated oxides, silicate rates and ratios of nitrogen and phosphorus had clays, and various organic complexes. "\'\nien a been applied at seeding. This method of appli- soil is flooded, the iron undergoes considerable cation greatly stimulated weed and grass growth changes in solubility, which is greatly influenced before the rice plants became established, and this by anaerobic bacteria. The extent of the change competition often severely reduced rice yield. is also a function of the organic matter content, However, the real worth of commercial fertilizers the low oxidation-reduction potential, and the became apparent with the gradual improvement soil reaction. Ferric iron, which predominates in of irrigation and drainage facilities, improved well-drained soils, is reduced to the ferrous form, land preparation, mechanized harvesting equip- especially as hydroxides and carbonates. Decom- ment, the development of varieties suitable for 70 Aonícu: .TURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE mechanization, and the greatly increased use of total growth period of the particular rice variety. the airplane for applying fertilizers. Fertilizers The rice soils in Louisiana and Texas are gen- were also greatly improved. Pelleted or prilled, erally deficient in phosphorus and in organic mat- granular, and large crystalline, high-analysis fer- ter (35). Thus additions of from 20 to 40 pounds tilizers are available and are ideally suited for of phosphoric acid per acre and from 40 to 80 application with the airplane or with improved pounds of nitrogen per acre are usually necessary ground equipment {l-^S), for the economical production of rice. In most in- Knowledge of previous cropping history and a stances, no potash is required. The small areas of soil test are useful in determining the amount and sandy soils in both States, however, sometimes kind of fertilizer to use on rice in some Southern respond to a 20- to 40-pound per acre application States (^, 28). Specific fertilizer recommenda- of potash. tions vary considerably between States and from When applying fertilizer as a topdressing on area to area within States, or even from farm to rice growing in heavy soils, placing it on dry soils farm within the same area. The rice variety, is usually preferred to placing it on wet or flooded water management, methods of weed control, and soils. Soon after the fertilizer is applied, the other managerial variables affect use of fertilizers fields are flooded; thus the water is an effective {15). Various rapid, chemical, soil-testing meth- carrier to move the fertilizer into the root area. ods are used effectively to determine the fertilizer If scarcity of irrigation w^ater, weed infestations, and lime requirements of rice soils (^). Chemical rains, or timing difficulties prevent flooding, the determination can be made on soil reaction (pH), rate of application, particularly of nitrogen, is percentage of organic matter, and the available increased slightly to compensate for reduced effi- phosphorus, potassium, and calcium; and the ciency. The rate for nitrogen should be increased salinity hazard can be noted. The nitrogen level about 5 to 10 percent on wet soils and perhaps is usually estimated from the organic matter con- 10 to 15 percent on flooded soils {28). tent. Results of these tests obtained from air- Applying a large amount of fertilizer directly dried soil samples can be interpreted with reason- with the seed is hazardous, since germination may able accuracy, provided basic information is avail- be reduced or emergence may be delayed. The able on the complex chemical changes known to time of seedling emergence directly influences occur under submergence. All this information is the flooding date and thus becomes important in of value in determining fertilizer requirements controlling grass weeds. These problems do not for rice in southern rice areas. ordinarily occur if the fertilizer is placed 2 to 3 Nitrogen is used at somewhat higher rates in inches below the seeds. Arkansas than in the other States. Rates above Limited research on the mineral deficiency 100 pounds per acre of actual nitrogen are rather symptoms of rice has been conducted in the common, particularly on the soils of the Grand United States. Olsen {22) reported typical foliar Prairie {Slf). Some differences in the fertilizer symptoms due to deficiencies of nitrogen, phos- requirements of rice varieties are recognized, with phorus, potassium, calcium, magnesium, and iron the stiffer strawed varieties being capable of using in three greenhouse experiments. A deficiency of and withstanding higher rates of nitrogen with- each of these elements, except calcium, reduced out lodging. Phosphorus and potash are usually tillering. Reduced tillering caused by nitrogen applied on the basis of a soil test. The nitrogen deficiency was particularly pronounced. All ele- requirements for rice grown in the delta areas of ments reduced root and top development; potas- Arkansas and Mississippi seldom exceed 60 to 80 sium and nitrogen deficiencies caused the most pounds per acre. These newer soils frequently severe reductions. require no fertilizer during the first year or two The sources of nitrogen, phosphorus, and po- of rice production. tassium used in southern rice areas vary widely The timing of fertilizer application on rice is and to a large extent depend on the cost of ap- very important. Most rice farmers in Louisiana plication and physical condition of the fertilizer. and Texas prefer a somewhat earlier application Ammoniacal forms of nitrogen are generally of the total amount of fertilizer than do farmers preferred to the nitrate forms; however, com- in Arkansas and Mississippi (5^). For all States, pounds containing both sources, such as ammo- however, it is generally conceded that all of the nium nitrate or mixtures of ammonium nitrate phosphorus and potassium and part of the nitro- and urea in liquid form, are considered equal on gen should be applied as near to seeding time as possible. In Louisiana and Texas, the remaining an equivalent nitrogen basis to such materials as ammonium sulfate, ammonium phosphate, urea, nitrogen should be applied before the rice has and ammonium chloride. Because of the lower completed half of its growth period. In Arkan- cost of application, there is a definite trend to- sas, a nitrogen application about 60 to 70 days ward the use of high-analysis fertilizers. Anhy- before harvesting has produced good results. drous ammonia is a good source of nitrogen for Thus, the timing depends to a large extent on the rice, although it is difficult to apply wâth ground RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 71 equipment during wet periods. Application in crop IS grown {18), Phosphorus fertilizers have water is satisfactory only when precise watering increased yields on the brownisli-red terrace soils metliods are used, since uniform distribution of bordering the Sacramento and the San Joaquin the material depends on having a uniform dis- Valleys. Some basin soils after years of crop- tribution and depth of water. ping i)roduce better rice yields when j^hosphoi'us Phosphorus is usuall}^ supplied in the form of is included with nitrogen. In some areas, usu- superphosphate (either 20 or 46 percent) ammo- ally parts of large fields, where alkali salts have nium phosphate, or diammonium phosphate. accumulated and where the soil reaction exceeds Rock phosphate is sometimes used and is satis- pH 8.5 in a 1:10 soil-water paste, dramatic re- factory. sponses have been obtained from various iron Muriate of potash (KCl) is the connnon source sources (9). of potassium. Only limited quantities of potas- Rice was fertilized in California before 1958 sium sulfate are used, although it is considered by broadcasting either on the dry seedbed before equal to muriate of potash. flooding and planting or, more commonly, In areas where crops preceding rice have been on the water by airplane after seeding. Ferti- fertilized with phosphorus and potash, residual lizer placement work of Mikkelsen and Finfrock amounts of these elements ma}^ be sufficient for (17) demonstrated that nitrogen broadcast on the one or perhaps two consecutive rice crops. soil surface or ap])lied to the flooded fields was Research has been conducted with minor ele- not used efficiently by rice. Broadcast nitrogen ments; however, no positive effects on jdelds or was lost through nitrification and subsequent milling quality have been reported. denitrification. However, annnonium nitrogen Addition of limestone has not been necessary drilled 2 to 4 inches into the soil, where reducing for rice grown on moderately to slightly acid conditions developed 3 to 5 days after flooding, (pH 5.0 to 6.5) soils. Of equal importance is remained in the soil and was continuously avail- the fact that no detrimental effects on rice yields able to the rice plants. have been noted from adding lime, which is The time of applying fertilizer before flooding usually added at the rate of 1 to 2 tons per acre is important, since nitrification is known to be on crops rotated with rice. undesirable both before and during flooding. The long growing seasons in southwestern Lou- Mikkelsen (16) established that nitrification oc- isiana and southeastern Texas permit the produc- curs if annnonium nitrogen is drilled into a warm, tion of a ratoon or stubble crop, particularly by moist, aerated seedbed before flooding. As much the earliest maturing rice varieties seeded around as 60 percent of the ammonium nitrogen can be the middle of AiDril. Research in Texas (8) has converted to nitrate in 7 days of typical spring shown that for best results, additional nitrogen, soil temperatures. usually about three-fourths of the amount ap- Split application of nitrogen, with part placed plied to the first crop, should be applied immedi- in the soil before flooding and the rest used as a ately after first harvest. This practice consist- topdressing during the ]3eriod of panicle forma- ently gave rice yields that were one-third to tion, has proved effective in some regions of the one-half as much as the original crop. Ordinar- world. To])dressing experiments in California ily, fertilizers containing phosphorus and potas- rice production have shown no superiority over sium need not be applied, since residual quantities preplant soil application (19). Where the seed- of these elements applied to the first crop fulfill iDed application of nitrogen was not sufficient to the ratoon requirements. maintain normal color and growth of rice, sup- plemental applications have been profitable. For California effective use of topdressed nitrogen on California Fertilizers, particularly nitrogen, increased rice varieties, the application should be made no rice yields in the earliest experiments conducted later than 50 to 60 days after planting. in California, in 1914-16 (11). Dunshee (7) Phosphate fertilizer should be applied before continued rice fertilizer research, and it was flooding, usually simultaneously with nitrogen. greatly expanded by Davis and Jones (6) from Phosphorus does not move appreciably from 1925 through 1937. They showed that nitrogen where it is applied ; this makes placement in the fertilizers improved yields significantly on Stock- root zone of great importance. ton clay adobe. Applications at the time of seed- The quantity of nitrogen fertilizer used in rice ing were more effective than were later applica- production varies from 30 to 120 pounds of actual tions. They also reported that phosphate and nitrogen per acre. This is supplied as one of the potassium fertilizers did not increase yields on commercially available ammoniacal sources such Stockton clay adobe. as ammonium sulfate, urea, anhydrous ammonia, More recent fertilizer research has demon- or ammonium phosphate sulfate mixtures. On strated the need for nitrogen on all soils except soil low in nitrogen, as much as 80 to 120 pounds those on which a good leguminous green manure of nitrogen per acre (400 to 600 pounds of ammo- 72 AGîatMLTLTUKE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE (5> CLARK, H. L., HALEY, G. J., HEBERT, E. J., and others. nmin sulfate) is often used. Soils of iivera^^e 1962. SOIL SURVEY OF ACADIA FARISII, LOUISIANA. fertility, producing about 50 hundredweight of U.S. Soil Conserv, Serv. in coop. La. Agr. paddy Vice, usually receive applications of 60 to Expt. Sta. Ser. 1959 No. 15, 57 pp. 80 pounds of actual nitrogen. (6) DAVIS, L. L., and .JONES, J. W. On most California rice soils, a])])lications of 1940 FERTILIZER EXPERIMENTS WITH RICE IN CALI- F(JRNIA. U.S. Dept. Agr. Tech. Bui. 718, 40 to 60 pounds of actual P2O5 per acre will sup- 21 pp. ply the phosphorus needs of rice. Some residual (7) DUNSHEE, C. F. eifects have been observed on subsequent crops, li)2S RICE EXPERI:MENTS IN THE SACRAMENTO VAL- but the carryover from a single application may LEY, 1922-1927. Calif. Agr. Expt. Sta. Biil. 454, 14 pp., i 11 us. not be sufficient for best yields during a second (8) EvATT, N. S., and BEACH ELL, FT. INI. year. In areas where phosphorus is needed, the 19(;2 SECOND-CROP RICE PRODUCTION IN TEXAS. added growth and yield often require that addi- Tex. Aíír. Prog. 8(6) : 25-28. tional nitrogen be supplied. Where rice produces ( 9 ) INGEBRETSEN, K., MARTIN, W. E., VLAMIS, JAMES, and .lETEH, ROY. better growth with phos])horus, it is generally 1959. IRON DEFICIENCY OF RICE. Calif. Agr. 13: advisable that nitrogen rates be increased 25 to 6-7, 8, and 14. 50 percent. (10) .TANSSEN, GEORGE, and METZGER, W. H. Experiments to determine the best nitrogen 1928. TRANSFORMATION OF NITROGEN IN RICE SOIL. sources for rice have been conducted over a long- Amer. Soc. Agron. .Jour. 20: 4.59-476. (11) JONES, J. W. period. Davis and Jones (6) compared ammo- 1928. RICE EXPERIMENTS AT THE BIGGS RICE FIELD nium sulfate, Ammo-Phos, Leunasal]:)eter, urea. STATION IN CALIFORNIA. U.S. Dept. Agr. Ammo Phos Ko, Leunaphos, Calurea, and cyan- Dept. Bui. 1155, 60 pp., illus. amide during 1932-36. They concluded that (12) — DocKiNs, J. O., WALKER, R. K., and DAVIS, W. C. ammonium sulfate was the most profitable. Ex- 1952. RICE PRODl'CTION IN THE SOUTHERN STATES. periments in which nitrogen from different U.S. Dept. Agr. Farmers' Bui. 2043, 36 pp., sources was drilled into the soil l)efore fiooding illus. are reported by ^Mikkelsen and Miller {19). In (13) ^MCGREGOR, A. J. 1953. PHOSPHATE MOVEMENT AND NATL^RAL DRAIN- yield comparisons with ammonium sulfate rated AGE. Jour. Soil Sei. 4: 86-97. as 100, ammonium chloride ranked 97, cyanamide (14) MANN, C. W., WARNER, J. F., WESTOVER, H. L., and 92, urea 90, aqua ammonia 85, anhydrous am- FERGUSON, J. E. monia S3, and ammonium nitrate 57. A(iua am- 1911. SOIL SI^RVEY OF THE WOODLAND AREA, CALI- monia and anlnalrous ammonia are good nitrogen FORNIA. U.S. Dept. Agr., Bur. Soils, Soil Survey Adv. Sheet 1909, 57 pp. sources but in h)ose diy seedl)eds tliey sometimes (15) MiEARS, R. .T. do not i)erform as well as do dry materials be- 1958. FERTILIZER AND CULTURE PROBLEMS. Rice cause of volatilization losses. Tech. Working Group Proc. 8 : 17-19. Ingebretsen and others (9) reported that in (16) ^IlKKELSEN, D. S. alkali spots where rice ordinarily died soon after 1962. NITROGEN FERTILIZATION OF JAPÓNICA RICE IN CALIFORNIA. Rice JouF. 65(3) : 8-13. emergence, l)roadcast applications of ferric sul- (17) and FiNFRocK, D. C. fate corrected iron deficiency and ])roduced ex- 1957. AVAILABILITY OF A^I^IONIACAL NITROGEN TO cellent yields. Su))sequent tests with other mate- LOWLAND RICE AS INFLI^ENCED BY FERTILIZER rials indicated that iron oxide, modified and PLACEMENT. AgTou. Jour. 49 : 296-300. natural iron sulfides, and ferrous sulfate likewise (18) FiNFRocK, D. C, and MILLER, M. D. 1958. RKE FERTILIZATION. Calif. Agr. Expt. Sta. corrected the deficiency. Usually 125 to 250 Ext. Serv. Leañet 96, 12 pp., illus. pounds of actual iron from these sources corrects ( 19 ) — and MILLER, M. D. the iron deficiency. 1963. NITROGEN FERTILIZATION OF RICE IN CALIFOB- NiA. Calif. Agr. 17 : 9-11. Selected References (20) MiTSLU, SHINGO. 1954. INORGANIC NUTRITION, FERTILIZATION AND SOIL AMELIORATION FOR LOWLAND RICE. 107 ( 1 ) ADAIR, C. K., and ENGLER, KYLE. pp. Yokeiido Ltd., Tokyo. 195Ó. THE IRRIGATION AND CULTIRE OF RICE. lU (21) Water, U.S. Dept. Agr. Yearbook of Agr , NELSON, MARTIN, SACHS, W. H., and AUSTIN, R. H. r)l). 389-304. 1923. THE SOILS OF ARKANSAS. Ark. Agr. Expt. (2 ) ALLISON, L. E. Sta. Bui. 187, 83 pp., illus. 1947. EFFECT OF MICROORGANISMS ON PERMEABILITY (22) OLSEN, K. L. OF SOIL UNDER PROLONGED SUBMERGENCE. 1958. .MINERAL DEFICIENCY SYMPTOMS IN RICE. Soil Sei. G3 : 439-450. Ark. Agr. Expt. Sta. Bui. 605, 11 pp. (3) HEACHELL, H. M. (23) PATRICK, W. H., JR., and STURGIS, M. B. 1959. RICE. In Matz, S. A., eel.. The Chemistry 1955. CONCENTRATION AND MOVEISIENT OF OXYGEN and Technoh)iJ:y of Cereals as Food and AS RELATED TO ABSORPTION OF A^[MONIUM Feed, pp. 137-176. Avi Pub. Co., Inc., West- AND NITRATE NITROGEN BY' RICE. Soil Sci. port, (\nm. Soc. Amer. Proc. 19: 59-62. (4) BEACHER, R. L. (24) PEARSALL, W. H. 1955. SAMPLING AND ANALYSLS OF PADDY SOILS. 1938. THE SOIL COMPLEX IN RELATION TO PLANT Internatl. Rice Comn. Meeting Proc, FAO, COMMUNITIES. I. OXIDATION-REDUCTION PO- Penang, Malaya. TENTIALS IN SOILS. Jour. Ecol. 26 : 180-193. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION (25) PEARSALL, W. H., and MOKTIMER, C. H. (31) STURGIS, M. B. 1939. OXIDATION-REDUCTION POTENTIALS IN WATEK- V,):M\. CMAN(iES IN THE OXlDATlON-KElK ( TlON EQUI- LOGCJED SOILS, NATURAL WATERS AND MUDS. Jour. Ecol. 27 : 483-501. LIBRIUM IN SOILS xiS RELATED 'i'( ) 1 HE PHYSI- CAL PKOPEUriES OF THE SOILS AND THE (20) REED, J. F., and STURGIS, M. B. 1939. CHEMICAL CHARACTERISTICS OF I'HE RICE AREA GROWTH OF KITE. La. Agr. P]xpt. Sta. Bui. OF LOUISIANA. La. Agi'. Expt. Sta. Bui. 307, 271, 37 1)}). 31 pp. (32 1 KETZER, J. L., GLASSEY, T. ^Y., GOFF, A. M., and (27) 11)57. MANAGING SOILS FOR RICE. /// Soil, U.S. HARRADINE, F. F. Dept. Agr. Yearl)()ok of Agr., pp. 658-663. 1951. SOIL SURVEY OF THE STOCKTON AREA, CALI- FORNIA. U.S. Dept. Ai^r. in coop. Univ. (33) TENNEY, F. G., and WAKSMAN, S. A. Calif. Agr. Expt. Sta. Ser. 1939 No. 10, 121 1930. COMPOSITION OF NATURAL ORGANIC MATERIALS pp. AND T1H:IR DECO^^IPOSITTON IN THE SOIL. V. (28) REYNOLDS, E. B. DECOMl'OSITION OF VARIOUS CHEMICAL CON- 1954. RESEARCH ON RICE PRODUCTION IN TEXAS. STITUENTS U\ PLANT MATERIALS, UNDER Tex. Agr. Expt. Sta. Bui. 775, 29 pp. ANAEROBIC CONDITIONS. Soil Sci. 30: 143- (29) SENEWIRATNE. S. T., and MIKKELSEN, D. S. 160. 1961. PHYSIOLOGICAL FACTORS LIMITING GROWTH AND YIELD OF ORYZA SATIVA UNDER FLOODED (34) THOMPSON, L., MAPLES, R., WELLS, J., and others. CONDITIONS. Plant and Soil 14 : 127-146. 19r]2. RECOMMENDATIONS FOR RICE FERTILIZATION IN (30) SHAPIRO R. E. socTHERN STATES. Rice Jour. 65(1) : 5, 6, 1954. THE EFFECT OF FLOODING ON AVAILABILITY OF and 40. SOIL PHOSPHORUS YIELD. AND PHOSPHORUS AND NITROGEN X^PTAKE BY RICE. FoUl'th lu- ( 35 ) WALKER, R. K., and MIEARS, R. J. ternatl. Rice Comn. Proc, Tokyo. [Mimeo- 1957. THE COASTAL PRAjRUis. lu Soil, U.S. Dept. graphed paper.] Agr. Yearbook of Agi\, pp. 531-534. CULTURE By T. H. JOHNSTON and M. D. MILLER Rice has been grown as a commercial crop in the United States since the Latter part of the 17th century. Rice cultural methods used from that time until the present have been reviewed by Adair, Miller, and Beachell (5).i They traced the evolution of cultural methods from the use of hand labor for clearing timber from the land, for digging canals and ditches, for plowing with a hoe, for seeding, harvesting, and threshing, through the use of animal power (oxen, mules, and horses) for binding and thresh- ing the rice. Then came steam-powered thresh- ers. Today, several large "rice-special" diesel- and gas-powered tractors and self-propelled com- bines may be used on one farm. Much of the seeding and most of the fertilizing and spraying is now done by airplanes that can cover several hundred acres a day. Much of the increase in rice production i^er acre can be attributed to imi)roved cultural meth- Ficu'EE 28.—A ricefield showing the canal that supplies the ods made possible by the invention and manufac- irrigation water. ture of the specialized equipment. The major rice areas of the United ¡States are now described infested with weeds and diseases that lower the as the most highly mechanized farming areas in yield and quality of the rice. the world. In the early 3'-ears in the Carolinas, rice was Along Avith improvements in machinery and grown continuously in the same field with only farming methods have come other innovations, occasional rest (4-4) • Later, ricefields in that including use of reservoii's for im])ruved water area sometimes were planted to oats in the fall, supply and, more recently, underground pipelines followed by })otatoes the next year. Some farm- to eliminate man}' open canals. ers grew rice and cotton in alternate years. This Rotation or cropping systems; land leveling helped to control weeds in both crops. and seedbed prepaiation; seed and seeding; irri- In the early years in the South Central States, gating (ñg. 28) ; and harvesting, drying, and fields were cropped to rice year after year until storing methods have been develoi)ed and im- the rice yields became low and the quality poor provecl through research. ]\Iany branches of because of the mixtures of weed seed and red science have contributed to the development and rice ill the threshed grain. Fields then were adaptation of new and improved methods, equip- allowed to lie idle for 1 or 2 years, and then ment, and facilities now used in rice culture. were again put back into rice. This helped to increase rice yields but did not control the weeds Rotation or Cropping Systems satisfactorily. Therefore, ricefields were grazed during the years that they were "laid-out." This In most rice-producing areas of the United practice helped to control grass and weeds but States, crops are rotated because under continu- did not control red rice. Some farmers practiced ous cropping the soil usually becomes dej^leted summer-fallowing for a year or two between rice in fertility and in organic matter. The resulting crops and in this way controlled weeds and red deterioration of the physical condition of the soil rice more effectively than when the fields were makes seedbed preparation esi^ecially difficult. In idle. addition, the soil usually becomes progressively Modern riceland cropping systems are based on information gained from controlled experi- 1 Italic numbers in parentheses refer to Selected Refer- ments and from groMer experience. The pre- ences, p. 106. ferred system for any farm depends on soil type. 74 RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 75 local climatic conditions, and economic considera- higher with only one-third of the land in rice tions. than with one-half of the land in rice, if other Arkansas crops such as oats, lespedeza, and soybeans were grown and harvested to supplement income. Rotation experiments Avere begun in 1927 at Forty percent of the operators of large rice the Rice Branch Experiment Station, Stuttgart, farms followed a cropping system including rice Ark. Because of the numerous factors knoAvn to and oats, with the oats in many cases being over- affect rice yields, many rotations were tried, seeded with lespedeza; and almost all operators along with several combinations of delayed seed- had some fallow and idle land. Approximately ing, tillage for weed control, and summer-fal- 25 percent of the farmers produced so^^beans, and lowing. Results included the following {93^ 94) : about 35 percent produced beef cattle. The sec- (1) In 2-, 3-, and i-year rotations, best yields ond most common rotation was rice-oats-lespe- were obtained when rice was grown not more deza-soybeans, with 42 percent of the land being than half the time. used for rice under this cropping system. (2) Rice rotated with fallow or early planted In 1962, the crops most often grown in rota- soybeans (for beans or hay) or lespedeza (for tion with rice in Arkansas were soybeans and hay) produced 1,000 pounds more rice per acre oats. Legume green manure crops were used in- in the year it was grown than when rice was frequently. In recent years, 1 or 2 years of les- grown continuousl5\ Over a 7-3?'ear period of pedeza in a rice rotation has sometimes led to continuous cropping, rice yields declined 180 considerable damage to rice from the so-called pounds per acre. lespedeza worm, grape colaspis, Maecolaspis (3) The best 3-year rotation was 1 3^ear of ßavida (Say). However, chemical controls for soybeans, followed by a winter vetch cover crop, this insect have been developed by Rolston and and 2 years of rice. Rice yield increase was Rouse (iö7). greatest the first year. The rotation of rice with reservoirs used for (4) As compared to continuous rice, 4:-yeav fish production and as a source of irrigation wa- rotations of soybeans-oats-rice gave large jdeld ter has been practiced in Arkansas {46). In increases in the first year of rice, but only half some instances, the rotation has produced sub- as large an increase in the second year of rice. stantial increases in rice vields, even without the (5) Rice yields Avere significantly increased bj^ use of commercial fertilizer on the rice crops. plowing down legume green manure crops, in- The rotation may include 2 years of fish and 2 cluding soybeans, lespedeza, and hairy vetch years of rice or 1 year of fish and 1 or 2 years of (Vida vUJosa Roth) immediately preceding the rice. Leaving a reservoir in fish for longer than rice crops. All green manure treatments in- 2 years is usually unsatisfactory because the ac- creased rice yield more than did chemical fertil- cumulated fertility results in excessive vegeta- izer applied to the preceding crop in the rotation. tive growth of the rice the first year after fish. Simmons {115) reviewed x^^rkansas rice rota- In some cases, even 2 years in fish results in ex- tion research, discussing 3-, 5-, 6-, and 8-year cessive vegetative growth and severe lodging of systems. These systems mvolvecl rice on the land the following rice crop. for half of the time or less and soybeans, oat«, Experiments by Sims {117. 118) indicate that lespedeza, or hairy vetch the rest of the time. a large part of the increased vegetative growth Perkins and Lund (100) listed ways in which of rice may be attributed to the accumulation of good rotations would benefit the farmer, but cau- ammonium nitrogen in the soil during the period tioned that these rotations would not replace the reservoirs were in water and fish. Excessive mineral plant food elements such as phosphorus vegetative growth of rice may be avoided by and potassium. They stated that legumes may growing a row crop such as soybeans, grain supply considerable nitrogen, but more nitrogen sorghum, or corn in the rotation the first year may be needed. They also stated that rotations following fish or water and then growing rice will aid in disease and insect control, but other the second year. In one field test on a clay soil control measures may be required. that had been in fish 2 years, all of these crops re- In 1947 the order of frequency of crops in the duced the ammonium nitrogen content of the Arkansas rice area was rice, oats, lespedeza, soy- soil from 175 pounds per acre at seeding time to beans, corn, and cotton {120), The most preva- 40 pounds per acre at harvest. Rice grown on lent cropping systems on small rice farms in the experimental area the second year did not Arkansas were 4 or 6 years long, with rice being lodge. grown on the land for 2 or 3 consecutive years In ricefields where high soil fertility resulted (ÖÖ, 91), These systems included growing rice in excessive early vegetative growth, draining and leaving the land idle, a rotation of rice, oats, the fields and allowing them to dry thoroughly and lespedeza, and a rotation of rice and soy- before the development of the rice panicles beans. Returns to the operators were slightly (heads) at the early jointing stage of growth 7G AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE helped retard later vegelalive o-rowth of the rice harvest, gave greater returns than were obtained and helped reduce lodging. from commercial fertilizer applied to the rice Green (45) reviewed the problems of fish farm- crop. In addition, the soil was left in a loose, ing and stated that haphazard raising of fish friable condition, which facilitated the prepa- must be supplanted by more scientific production ration of a better rice seedbed. and marketing practices. Jenkins and Jones {62) in 1944 pointed out Green and White (^7) recently have compared that the rice crop, like other cereals, responds to three selected 4-year rice rotations in eastern appropriate cultural methods and rotation sys- Arkansas. These rotations were fish-fish-rice- tems. At the time their experiments were started rice, soybeans-soybeans-rice-rice, and idle-fallow- in 1934, the rice crop normally was grown in rice-rice. Combinations of buffalo and bass were alternate years or once in 3 years on land fal- the fish species most commonly stocked. These lowed or îeft in stubble pasture for 1 or 2 years. studies indicated that a total of 881 pounds of In 2-year rotations, the highest yields of rice buffalo and 181 pounds of bass per acre must be were obtained following Italian ryegrass, clov- produced and marketed during the 2-year fish ers, or stubble pasture. Another experiment period for this system of land management to be demonstrated how other crops grown in the ro- as profitable as the soybean-rice rotation. This tation may influence rice yield. The average level of production is considerably higher than yield of rice following cotton that had been that reported by the 35 fish-rice farmers whose dusted with calcium arsenate was 30 percent operations were included in the study. below the yield following cotton that had not Preliminary experiments conducted at the Rice been dusted. The reduced yield apparently was Experiment Station at Crowley, La., showed that due to the adverse residual effect of the cal- good-quality catfish could be produced under cium arsenate upon the ensuing rice crop. Reed conditions similar to those in flooded ricefields and Sturgis {lOJf) in 1936 showed that arsenic without major disease or parasite problems toxicity symptoms in the rice plants are similar {128). To help answer some of the complex to those of straighthead in which case florets problems encountered in the growing of fish and may be distorted and seed set may be reduced in the use of fish-rice rotations, a Fish Fanning markedly. Experimental Station was established in 1961 at The average yields of cotton and soybeans in Stuttgart, Ark., by the Fish and AVildlife Serv- a 3-year rotation of cotton, soybeans, and rice ice of the U.S. Department of the Interior. In were too low to be profitable, and the average cooperation with the University of Arkansas, ex- yields of rice was slightly less from this rotation periments have been initiated to determine suit- than from the better 2-year rotations. able management and fertilization practices In 4-year rotations consisting of rice 2 years {116), followed either by 2 years of cotton (fertilized Sullivan (136) reported that some Arkansas and not fertilized) or hj 2 years of native pas- farmers in recent years have started to rotate ture (fertilized and not fertilized), the yields of water and crops. Their fields are kept flooded 1 rice were not increased hj fertilizing; but the or 2 years and then seeded to rice. According to rice following native pasture jnelded somewhat Sullivan, benefits under this system include in- more than did the rice following cotton. creased organic matter content of the soil, im- In 10-year rotations of 5 successive i*ice crops proved physical soil characteristics, improved following 5 years each in (1) improved pasture, weed control, and improved recreational and (2) native pasture, (3) corn plus soybeans, or wildlife facilities. (4) cotton, the 4-year average yield per acre of Louisiana rice was 2,192 pounds following improved pas- ture; 2,120 pounds following native pasture; Reporting on early experiments in rice pro- 2,052 pounds following corn plus soybeans; and duction in southwestern Louisiana, Chambliss 1,444 pounds following cotton dusted with cal- and Jenkins {19) in 1925 stated: ''Good drain- cium arsenate. age, good tillage, and proper rotation make un- On land cropped continuously to rice for 49 necessary the application of any commercial fer- years, the average annual yields for successive tilizer to the Crowley silt loam at the present 5-year periods during the la*st 30 of the 49 years time." Results obtained at the Crowley Rice ranged from 1,102 to 1,440 pounds per acre. Fluc- Experiment Station from 1913 to 1923, inclu- tuations in the 5-year average yields apparently sive, showed that rice in rotation with soybeans were due to variations in climatic conditions and averaged 2,384 pounds per acre, as compared were not the result of depletion of the soil fer- with 1,243 pounds per acre for continuous rice. tility, according to Jenkins and Jones {62). Efficient drainage and good tillage, supplemented Walker and Sturgis {IJ^l) reported in 1946 by the organic matter added to the soil by plow- that pasture-rice rotation experiments begun in mg under mature soybean plant remnants after 1938 and conducted on three soil types of the RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 77 prairie rice area of Louisiana showed that a 12- land was in rice each year, but the increase in month grazing program could be developed. They rice jnelds was sufficient to maintain about the stated that up to that time the rotation of im- same total volume of rice production on the proved pasture with rice definitel^^ was the best farm. means found of increasing rice yields and of A rotation of rice for 2 years and temporary improving the soil productivity of the area. Also, pasture for 3 years gave an average rice yield of where proper management practices were used, 2,600 pounds per acre, as compared with 1,950 yields of beef from improved pxistures exceeded pounds per acre from rice alternated with native yields from unimproved pastures by more than pasture in a 2-year rotation. When rice was 150 pounds per acre. In addition, turning under grown for 2 years following 3 years of tempo- improved-pasture sod ahead of rice crops in- rary pasture, the estimated average rice yield creased rice yields 1,000 to 1,800 pounds per acre. for the 2 years was about 3,250 pounds per acre. Black and Walker (16) reported in 1955 on a Leaving land in pasture for a fourth year added 5-year rotation experiment that Avas established an additional 150 pounds per acre to this aver- at five locations in Louisiana, from 1946 to 1953, age rice yield. In addition, the quality of rice on four soil types. The results of these five ex- improved and this, combined with higher pro- periments substantiated earlier work on pasture- duction of beef feeding on the temporary pas- rice rotation in southwest Louisiana. Thej' found ture, gave substantially higher net return to rice that if improved pastures are established, it is farmers. desirable to provide contour levees and irriga- tion during dry periods, so that full benefits can Mississippi be received from the relatively large investment Thompson and Waller (137) in 1952 suggested required to establish improved pastures. Also, using rotations of rice-soybeans-soybeans or rice- it was necessary to obtain a minimum of 3 years' lespedeza( for haj^ or grazing)-soj^beans in Mis- grazing from an improved pasture before plant- sissippi. As recently as 1962, Anderson and ing it to rice, since an improved pasture produces McKie (11) cautioned growers about substan- only about two-thirds as much in the first year tially decreased yields from growing continuous as in the second and third years, and the initial rice and suggested that a field be held out of rice cost of an improved pasture is fairly high. Black for 2 to 4 years, during which time the weed and Walker concluded that in southwest Louisi- population should be reduced. Rice was com- ana a long-time rotation of improved pasture monly grown 2 years and was followed by fal- and rice is superior to the more common rotation low or soybeans. Some growers also used wheat of 1 year of rice followed by 1 3^ear of native and oats in the rotation. pasture. :\Iullins (89) m 1960 pointed out that in Mis- Davis, Sonnier, and White (¿i) in 1963 de- sissippi rice is grown in the delta area on clay scribed an experiment initiated in 1953 to deter- soils. When a relatively short rotation period mine the optimum length of time for pasture- of 2 to 3 years is used, farmers generally sum- rice rotations in southwest Louisiana. Rotations mer-fallow about as much land as they seed to included 1 year native or improved pasture and rice. The fallowed land requires little prepara- 1 year rice; 2 years improved pasture and 1 year tion for seeding the next spring. Rice is not rice; 3 j^ears improved pasture and 2 years rice; grown on the same field for the second year in and 4 years improved pasture and 2 j'Cars rice. such rotations, and rotational crops such as soy- Fertilization practices varied according to needs beans or small grains usually are omitted. shown by soil tests and good agronomic practices. Some growers use a 5- or 6-year rotation, with In this study, length of rotation and pasture rice 2 years and then no rice for 3 or 4 years. treatment had little effect on yield of rice. This When delta rice farmers use longer crop rota- is believed to be the result of using more fertilizer tion systems, at least half of the rice each year and the fact that existing soil conditions were is seeded on land that grew either rice or other somewhat better in this experiment than in earlier crops the previous year. Where rice followed experiments in the area. Improved pastures in rice, a few operators burned the stubble to facili- the rotation increased the yield of beef more than tate land preparation for the second year of rice. 500 percent. In these longer rotations, the major crop grown In reporting on an economic appraisal of farm in rotation with rice was soybeans. The next practices and rotation programs on Louisiana most commonl)^ grown crop was wheat. On a rice farms, MuUins (88) in 1954 pointed out that small number of farms, oats were grown. the most common rotation at that time was 1 year Where adequate surface drainage was avail- of rice and 1 or 2 years of native pasture. Some able, wheat and oats were well adapted to the longer rotations were being used such as rice 2 clay soils of the rice farms in Mississippi. These years and improved pasture 3 or 4 years. In the small grain crops fit reasonablly well into the rice longer rotations a smaller proportion of the crop- rotation programs. They usually were seeded on 78 AGRIGULTLiRE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE land that had lain idle and had been fallowed the pounds per acre, as compared with 1,800 pounds previous summer or on land from which early- where the rice did not follow clover. These re- maturing soybeans had been harvested. Small sults led to investigations started in 1946 on the grains following soybeans did not always pro- rapid, low-cost conversion from rice to improved duce satisfactory yields because there was only a pasture in rice-pasture systems. short time to prepare a suitable seedbed. This As reported by Reynolds (105), Moncrief and sometimes delayed seeding of small grains and Weihing found it practical to convert from rice the delay often led to damage from winterkill- to pasture by broadcasting grass and clover seed, ing. AVliere the harvesting of small grain was without seedbed preparation, in standing rice at not delayed, it was possible to double crop the the last draining about 10 days before harvest land with late-planted soybeans. Because of the and in rice stubble after harvest. The levees risk, some growers preferred to summer-fallow and drainage ditches used to irrigate and drain the land before seeding rice or soybeans the fol- the rice w^ere used to irrigate and drain the lowing spring. improved pastures. In the more humid areas a mixture of dallisgrass and clover (Louisiana Missouri white, Persian, and large hop) was successful. Experiments in Missouri reported by King In drier areas Hubam sweetclover w^as a more {7Jf) in 1937 demonstrated that crop rotation satisfactory legume. It was found that bermuda- was essential to continued high rice yields on grass usually volunteered. Ryegrass, tall fescue, Wabash clay (gumbo) soils. In a 6-year period, and cereals were seeded successfully at the last yields on continuous rice plots dropped to 450 draining of the ricefields and in the rice stubble. pounds per acre because of infestation with Lespedeza could be established by broadcasting weeds. Rice yields were as high from a 2-year the seed in rice stubble in late February or early rotation of rice and so5^beans as from 4-year March. rotations that included rice and other crops such Rice yields following improved pastures were as soybeans, wheat, clover, and corn. increased by 20 percent or more. In addition, as much as 200 pounds of annual beef gains per acre Texas were obtained on the improved pastures, as com- In a review of research on rice production in pared with less than 50 pounds on unseeded, un- Texas, Reynolds {105) stated: ''High yields of fertilized pasture fields. The clovers and ber- rice have not been sustained by growing rice on mudagrass, and sometimes dallisgrass, volun- the same land every year. Xor has the growing teered after the rice crop to provide grasses and of cultivated crops in rotation with rice proved legumes for the next pasture period. In some practical in most of the Texas rice belt.'' cases, pasture seed and hay could be harvested It is a common practice to grow rice 1 or 2 from these fields. years and to follow tliis with several years of In summary, Reynolds (105) stated: ''The sev- § razing beef cattle on volunteer vegetation, eral possible rice-pasture systems of farming have ometimes the land is mereh^ left idle for 2 years not been fully evaluated. However, such sys- or more. When rice follows unimproved pasture tems as 2 years rice, 3 years pasture; 2 or 3 years or idle land, the improved physical condition and rice, several years pasture; 1 year rice, 2 to 3 the increased organic matter content of the soil years pasture seem to be worth considering in increase rice yields. systems to maintain and improve soil tilth and Workers at the Beaumont station started re- productivit}^ between rice crops, as well as for search on rotations and cropping systems in 1913. providing j^ear-long grazing of nutritious forage From 1931 to 1941, a number of rotations were for beef cattle on rice farms.'' tried. The average yields of rice per acre were In a report on their studies of year-long graz- as follows: continuous rice, 1,072 pounds; con- ing in the rice-pasture system of farming, Weih- tinuous rice with fall-seeded sourclover (MelUo- ing, Moncrief, and Davis (146) reported that tiis indica (L.) AIL), 1,194 pounds; rice 1 year the unimproved pastures were grazed only 201 and idle 1 year, 1,613 pounds; rice 1 year, fal- days during the j^ear, whereas the improved pas- low 1 3^ear, 1,635 pounds; rice 1 year,^ cotton 1 tures were gi'azecl the full 365 days. In addition, year, 1,707 pounds; rice 1 year, soybeans 1 year, the carrying capacity of the improved pastures 1,618 pounds; rice 1 year, sesbania 1 year, 1,725 was about three times that of the unimproved pounds; rice 1 year, crotalaria 1 year, 1,642 pastures from April 14 to November 7, 1949; and pounds. gains on the improved pastures were nearly four ^ Studies from 1943 to 1945 indicated that rota- times those on unimproved pastures. Manage- tions of alyceclover for pasture and rice were ment practices, including fertilization and inocu- more satisfactory than were other rotations. Rice lation of clover seed, were important in estab- following alyceclover produced 2,500 to 2,860 lishing improved pastures. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 79 Evatt and Weihing (33) reported that rice fol- ricelands for a period of 3 to 10 years continu- lowing improved pastnres prodnced 650 to 800 ousl}^ aud still obtain increasing yields. In 1920, pounds more per acre than did rice following California's average rice yield was 2,205 pounds unimproved pastnres when eqnal amounts of fer- per acre; in 1003, it was 4,505 i^ounds per acre. tilizer were used. The rotations hiclnded in this A number of cash crops are well adapted for study were (1) rice and nnimpro^'ed pasture in growing in rotation with rice in California. The alternate j^ears; (2) improved pasture 3 years, ones most commonly grown are those providing rice, unimproved pasture, rice; (3) improved the best immediate economic advantage. One pasture 4 years, rice 2 j^ears; and (4) improved rotation involves rice; s^Dring- or early summer- pasture 5 years, rice 3 years. plowed fallow; and fall-sown wheat, oats, or Katooning is the harvesting of a second grain oats and vetch. Another includes rice; spring- crop from regrowth of the first rice stubble. The sown grain sorghum or field beans; and fall- practice is only possible when well-adapted short- sown wheat, oats, or oats and vetch. Safflow^er season varieties are grown and the area enjoys may be grown in rotation with rice but produc- about 280 frost-free days (41). About 35 per- tion usually is more successful when this crop is cent of Texas rice acreage was ratooned in 1963.^ grown the second, rather than the first, j^ear after Evatt and Beachell [Sß) discussed ratoon crop- rice. ping of short-season rice varieties in Texas. They Two rotational cash crops are sometimes har- reported that the technique appears to be a prac- vested the same j^ear. Wheat or oats may be tical means of increasing rice yields, provided followed by irrigated grain sorghum, field beans, varieties that mature the first crop in 100 to 105 or safläower. For successful double cropping on days are used. It requires about 70 to 80 days riceland, all operations must be expertly timed. to produce the second crop if all operations are Other crops used occasionally on the better properly executed. quality, medium-textured riceland soils include Although ratooning now appears to be a prac- sugarbeets, melons for seed, tomatoes, and alfalfa, tical and possibly profitable operation in United States areas having a suitable climate, expert Williams, Finfrock, and Miller (JW) reported management is recjuired. Evatt and Beax?hell that purple vetch (Ticla atívpurpurea Desf.), (33) have shown that the stubble of the first burclover [Medicago hispida Gaertn.), horse- crop should be at least 16 to 18 inches high. Leav- beans (Yicia' faha L.), and field peas {Pisum ing a shorter stubble delays recovery. Significant œrvense L.) were commonly used in ricelands for yield increases have been obtained from the ra- winter-grown cover crop and green manure. They toon crop by applyin«: up to 120 pounds of nitro- reported that leguminous green manures were gen per acre immediately after the first harvest. grown and turned under on about one-fifth of The stubble is reflooded when regrowth is 18 to California's riceland and that the practice is ex- 20 inches high. Usmg the early variety Nato, panding rapidly. these authors reported 4,048 pounds per acre Land Leveling and Seedbed Preparation from the first crop and 2,382 pounds per acre from the ratoon harvest, for a total of 6,430 Jones and others {69) reported that most land pounds per acre from a ¿ingle seeding. on which rice is grown is comparatively level, with a gentle slope toward the drainage chan- California nels. The cost of developing for irrigation lands Xo clear-cut rotation pattern has yet become with from 0.01- to 0.50-percent slope usually is established for California riceland (6*8) for the economical. A competent surveyor is employed following reasons : to locate the irrigation canal, drainage ditches, (1) The soil used for rice production generally and field levees. Improper location of canals, is inherently quite fertile. Hence, with the rela- ditches, and levees may cause serious losses, since tively short cropjping history as compared with it may result in faulty irrigation and poor drain- other rice States, soil nutrient depletion, with age. Irrigation canals should be large enough to the exception of nitrogen, has not yet proved a supply ample water promptly when needed. limiting factor. Drainage ditches should likewise be large enough (2) No serious rice disease has appeared to to dispose of water rapidly. date to force a rigid crop rotation program for Land Grading and Leveling disease control purposes. (3) The rapidly advancing knowledge of weed A general discussion of land leveling for irri- control, crop fertilization, and other improved gation has been published by Bamesberger {IJf). cultural practices has made it possible to crop Technical reports of land grading (land forming) for surface irrigation by Gattis, Koch, and McVey 2 EVATT, N. S. Texas A & M University, Beaumont, Tex. {JfO) and Marr {82) discuss the factors to con- 1964. [Correspondence.] sider before land grading is undertaken. These 82 AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE Texas, experience has shown that heavy soils, such as Beaumont clay and Lake Charles clay, generally require more subsequent tillage, such as disking and harrowing, to obtain a desirable seedbed when plowed in the spring than when plowed in the fall or early winter {105). Usually California ricelands are spring plowed to a depth of -t to 6 inches, after the stubble of the previous crop has been partly reduced by burning. The straw may be burned in the fall inmiediately after rice harvest if dry weather continues long enough. Spring-plowed soils make a better seedbed if allowed to dry for a week to 10 days after plowing before beginning the final seedbed operations. Davis {26) reported that water-seeded rice germinates better, has more seedling vigor, and produces a heavier crop when sown on a seedbed that is dry during the finish- ing operations. A seedbed prepared under moist conditions for water seeding induces algae (scum) development, increases weed problems, and fre- quently results in a poor stand because of poor germination and seedling vigor. Finfrock and Miller {36) reported that a good winter-grown vetch cover crop aids in drying out riceland soil, thereby making it possible to pre- pare the seedbed earlier. Cover crops turned un- " '^py'oß't"': der for green manure are usually plowed down with a moldboard or a disk plow. For best re- sults in California, the plant material should be completelj' covered with 4 to 6 inches of soil, according to Williams and others {lJp8^ H^). Seedbed Preparation as Related to Method of Seeding Rice may be seeded either by drilling on dry ground, or by broadcast seeding with an endgate seeder or airplane on dry ground or in flooded fields. The final seedbed preparation is influ- enced by the method of seeding to be used. If fields are to be water seeded, growers sometimes are able to prepare a fairly good seedbed in the late fall or winter and to erect their levees at this time. When this is possible, very little land preparation other than harrowing is necessary in the spring. In the Southern States, if the field is to be dry seeded with a drill or Avith an end- FIGURE 31.—Preparing the .seedbed : A, Moldboard plow ; gate seeder or broadcast by airplane, the final B, field cultivator with spike-tooth harrow attached ; preparation of the field includes working over 0, disk harrow. the levees while the field is worked. When rice is to be seeded, the final preparation just ahead ally it is not necessary to ploAV in the spring the of the drill usually is clone with a spring-tooth fields that were plowed the previous summer or or disk harrow behind which is drawn a spike- fall, except on poorly drained soil or during tooth harrow. This gives a mellow firm seedbed, seasons of heavy rainfall. and the moisture is held near the surface so the In general, land plowed in the spring should seed usually will germinate soon after seeding be disked and harrowed as soon as possible after without irrigating the field. A roller-packer may plowing to break up any large lumps and clods, be used in order to break up clods before drilling to prevent baking or crusting, and to avoid sub- and to firm the soil after drilling to help retain sequent difficulty in preparing the seedbed. In moisture. Usually, the levees are reseeded after RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 83 they have been parti}' rebuilt, and the seed then eter. This is done in California by harrowing is covered by the final building of the levees with twice with a heavy spike-tooth harrow followed a levee disk or a pusher-type levee maker. by dragging with a heavy wooden di'ag. A If rice is to be broadcast seeded on dry ground, rough seedbed helps prevent drifting of water- the final seedbed preparation leaves the surface sown seed. As the clods slake down ¡ifter Hood- rough and somewhat cloddy. The seed usually is ing and seeding, a fine film of soil may cover the covered by a shallow working with a spring- seed. In the South, the levees usually are seeded tooth, spike-tooth, or disk harrow^ Seed on the separately. In California, the levees are con- levees is covered by the final working with the siderably higher and larger and are not seeded. levee disk or pusher. In most cases, precipita- Some farmers have been successful in prepar- tion following seeding is necessary to bring ing their land in relatively stale water by draw- about germination and emergence of the rice ing spring-tooth or spike-tooth harrows through seedlings. the fields in the mud or in fairly deep water. If a field is to be water seeded, the final seed- Other growers who have attempted this method bed preparation depends somewhat on soil type. have found it very unsatisfactory. On sandy or silt loam soil, a mellow, firm seed- bed similar to that for drilling should be pre- Construction of Levees pared. Levees are constructed and are seeded Ricefields are divided by levees into subfields, just before the final working with a levee disk called paddies or bays (cuts). Levee construc- or pusher. The renuiinder of the field is worked tion is an important operation in preparation for between the levees with a spring-tooth harrow, which leaves fairly deep furrows into which the growing rice because levees are the kev device for seeds fall as they settle through the water. regulating water depth in ricefields. They must TVlien rice is water seeded on clay or very fine be located accurately and must be well constructed silt loam soil, the seedbed should be fairly rough in order to maintain a uniform depth of water with a clod size ranging up to 4 inches in diam- within each paddy (fig. 32). FIGURE 32.—Making levees with {A) disk, (Ü) pusher, and (C) plastic. 84 AGRICULTURE llANI>l^>OOK 2 8 9, U.8. DEFT. OF AGRICULTURE The levees are constructed on the contour, that m the fall with a base of 5 to 6 feet and are is, on lines of equal elevation. They should be allowed to settle during the winter. A bulldozer located by an experienced surveyor or operator or a tractor wáth a front-end scoop is used to who uses an accurate instrument. Because a close the gap at the water control boxes and at smooth soil surface is needed for accurate location the end of each levee. of the levees, the surveying should be done imme- Lewis and others {75) and Scott ancl others diately after the held has been floated. On flat {113) reported on the possibility of using rice land, the difference in elevation between levees is ievees made of plastic film in lieu of levees made 0.1 to 0.2 foot, and on steep, sloping land it is 0.3 of soil. Their studies show^ that plastic levees foot {37. 69). In fields where the levees run are physically feasible. Their commercial fea- parallel to the direction of the prevailing wind, sibility^ probably depends on the development of it is desirable, especially if the paddy is large, to a machine to 'economically install the plastic build wind levees at right angles to the direction levees. Prototype, privately developed machines of the prevailing wind. These levees are not tied to install plastic levees mechanically were oper- into the border or contour levees. Their function ated experimentallv in California in 1962 and in is to reduce the effect of the wind and thereby 1963. decrease wave action and reduce the possibility of levees being washed out. Seed and Seeding The levee should be compact and high enough to hold the water at an average depth of 3 to 6 The choice of seed and the use of suitable seed- inches in the paddy. In the Southern States, the ing methods are an important part of rice culture. levees have gently sloping sides, so that they may To achieve a high level of production, the variety be crossed with cultivating and harvesting equip- to l:)e grown must be adapted for the area. After ment. Here, the levees are completed after the deciding on the variety, it is necessary to select a rice is drilled. Levees of this type are considered lot of rice seed that is free from varietal mixtures, very efficient, for an entire field can be cultivated, does not contain red rice and weed seed, is high in seecled, and harvested as a single unit. percentage of viable seed, and has high bushel In California, the levees are higher and have weight. All rice-producing States now have a steep sides so as to hold a deeper flood; and the rice seed certification program designed to pro- areas between pairs of levees must be harvested vide high-quality seed for the rice industry. as a field or unit. This increases farming costs Before 1941, when combine harvesting, artificial because it increases machinery-maneuvering time. drying, and bulk storage Avere begun in the south- In addition, the land area devoted to high levees ern rice area, there was little incentive to develop is nonproductive. a seed rice industry. Varietal mixtures resulting In the Southern States, the base of the levee from handling were not serious when binders, commonly is made by plowing one round with a stationary threshers, and sack storage were used. 3-bottom plow. Levees are constructed with a Seed rice usually was saved from fields or parts levee disk usually mounted on the rear of a large of fields of known varietal purity. Weed seeds tractor, or commonly with a single- or double- and trash were removed by fanning mills and blade puslier on clay soils. The levee base is disk or cylinder graders usually owned and op- built as early as possible, so that it will become erated by private or grower organizations. How- compact before flooding time. This is especially ever, as combine harvesting, artificial drying, and important on hea^\y clay soils on Avhich levee con- bulk storage deA^eloped, varietal mixtures became struction often is difficult. Compact, well-settled serious. It was at this time that seed production levees reduce seepage and are less likely to be and processing developed into a specialized busi- washed out by excess water from heavy rains. ness. Today, much of the seed rice sown in the Well-constructed levees, properly repaired after Southern States is given specialized attention seeding, facilitate irrigation and eliminate much during growing, harvesting, drying, and process- expensive hand shoveling. Much of the vrork of ing. As a result, the seed rice industry is well installing levee gates and closing the gaps at the developed today. Foreign demand for seed of ends of the levees is done with pickup blades or high quality has further stimulated the develop- scoops mounted on small tractors. This elimi- ment of the seed rice industry. Substantial quan- nates much of the hand labor formerly required. tities of seed rice are exported annually to Central In California, a V-type diker or soil crowder and South American countries. that is 14 to 16 feet wide in front and 4 feet wide in the back is used to build levees. Two or more Seed Quality heavy-duty, crawler-type tractors are used to pull Numerous w^orkers have stressed the desirability the diker. The levees usually are from 30 to 36 of using seed rice of good quality {18, 27, 70, lU)^ inches high when freshly made and settle to be- Good seed should be well matured and free from tween 16 to 20 inches. Levees usually are made red rice, immature and hulled or broken grains, RICE IN THE UNITED STATES ! VARIETIES iVND PRODUCTION seed of other varieties, and weed seeds. The seed Red rice grains are difficult to remove from should be cleaned and graded to remove hulls, short- and medium-grain varieties because of the trash, and other foreign matter. Also, good seed similarity in diameter between tliose varieties and should germinate satisfactorily and should pro- red rice. Since red rice grains cannot be effec- duce strong sprouts. Using seed that germinates tively removed from the medium- and short-grain poorly may result in uneven stands, uneven ripen- varieties, it is essential to use seed free from ing, and low field yields of poor milling quality. red rice! Smith [12If) reported in 1940 that seed lots The origin of high-quality seed rice and the used on 29 farms were examined, and only 4 were certihcation of rice seed is discussed in the sec- found to be free of weed seeds and red rice. tion on ''Eice Breeding and Testing Methods in Today, most rice seed is thoroughly cleaned and the Ignited States/' p. 56. graded. Consequently, it is free of weed seed and has only a trace of hulled or poorly filled grains. Source of Seed Much emphasis has been placed on the import- Jones and others (67) studied the effect of en- ance of eliminating red rice from planting seed vironment and source of seed on yield and other (3, 70). Red rice is objectionable because the red characters of a group of varieties at four rice ex- bran is not completely removed in milling. This periment stations in Arkansas, Louisiana, Texas, results in an unattractive appearance when milled. and California. They concluded that seed source Also, the grain size, shape, and milling quality had no appreciable effect on grain test weight, are inferior. Red rice tillers profusely and shat- germination of seed, average grain and kernel ters easily, and seeds that have become buried in weights within a variety, proportion of hulls, and the soil have been known to remain viable for milling quality. In summary, they stated that several years {19, J/.S). '\A^ien rice seed containing ''local seed of good qualit}^, free of mixtures and red rice was seeded several years in succession on weed seed, is as productive as that obtained from the same land and red rice was not controlled, other rice-producing States.'' over 50 percent of the harvested grain was red rice (3). In a ricefield in Louisiana, over 500 red Seed Treatment rice grains were found in the top 6 inches of each Finfrock and Miller (36) reported that Cali- square foot of soil.^ fornia growers usually soak their rice seed in a The importance of using seed free from red rice sodium hypochlorite solution at the rate of 1 gal- cannot be overemphasized l>ecause as long as red lon of household bleach (5.25 percent of NaOCl) rice is being sown, it cannot be eliminated from per 100 gallons of water. In addition to provid- the fields. Based on a seeding rate of 80 pounds ing some protection against seedling diseases, the per acre, seed containing 5 red rice grains per chemical deactivates germination inhibitors lo- pound would probably result in approximately cated in rice hulls. 200 red rice plants per acre. At the Beaumont Mikkelsen and Sinah (54) reported the pres- Rice-Pasture Research and Extension Center, ence of six compounds in the hulls of Caloro rice land was cropped 2 consecutive years, in 1946 that diffuse into the embryo and inhibit germina- and 1947, and seed was used that contained ap- tion when present in large amounts. Compounds proximately two red rice grains per pound. The identified included vanillic acid, ferulic acid, grain harvested the first year contained about 18 p-hydroxybenzoic acid, p-coumoric acid, p-hy- red rice grains per pound and that harvested the droxybenzaldehyde, and possibly idoleacetic acid. second year contained over 125 grains.'^ In low concentrations, these chemical substances Seed rice free from red rice was nearly non- stimulate germination and ensuing growth. existent until 10 years ago. Screen graders, Leaching the seed by soaking with water reduces which effectively grade seed rice on a grain the concentration to stimulatory levels. The diameter basis, have been effective in removing probable action of sodium hypochlorite solution the broader red rice grains from long-grain var- is to modify these inhibitors so that seedling ieties. The screen graders, along with the pro- growth is stimulated. duction and increase of seed stocks free from red Garrison (39) reported on work with other rice, have effectively controlled red rice. In a small grains conducted by Earhart. Results few instances, slender red rice grains that can- showed that there is a definite need for all small not be separated from long-grain varieties have grain seed to be completely processed, including been observed. Whenever a seed lot that con- thorough cleaning and treating. For every 100 tains such types is observed, it should be dis- field-run seeds put in the ground, only 58 healthy carded immediately. plants were produced. '\'\^ien seed from the same lot was cleaned, 65 healthy plants were produced; ^BAKEE, J. B, Louisiana State Univ., Baton Rouge, and when the seed was both cleaned and treated, La. 1963. [Correspondence.] ^BEACHELL, H. M. Rice-Pasture Research and Exten- 72 healthy plants were produced. Field experi- sion Center, Beaumont, Tex. 1963. [UnpubUshed data.] ments comprising two rice varieties, sown at two 86 ItírUGULTOTvE HANDBOOK 2 8 9. U.S. DEFT, OF AGPaCULTURE dates at each of three locations for 2 years, practices. They pointed out that heavy rates of showed an average survival of 01 percent for nitrogen fertilization, particularly when applied seed treated with two commonly used seed-treat- late, tend to delay maturity. ment chemicals, compared with 52 percent for Results from date of seeding experiments indi- untreated seed (Í2). cate that there is a comparatively long period in Information on the treatment of rice seed to the South during which rice can be sown and still prevent seedling blight is given m the section produce satisfactory yields. It is possible and often advisable to spread the seeding time of cer- ^^Rice Diseases," p. 113. tain varieties so that the harvest can be extended Time of Seeding over a longer period. However, Adair (4), who studied the effect of time of seecling on yield and Seeding of rice in the United States begins milling quality in Arkansas, concluded that most when the weather becomes warm enough for of the early and midseason varieties produced rice germination and seedling growth. In Arkansas, of better milling quality when they matured late Mississippi, Missouri, and California, where the in September or early in October than when they growing season is comparatively short, seeding matured before September 15. Jodon (63) stated usually is done in April and May, within a period that since the approximate number of days re- of 3 to 5 weeks. Near the Gulf Coast in Louisi- quired from seeding to maturity is known for all ana and Texas, rice can be sown from early March commercial varieties, it may be desirable to base to late June—although most seeding is done in the date of seeding on the number of days re- April. c^uired for maturity, so that the rice will mature The length of seeding period depends mostly in the fall when the weather is usually dry and on the length of life cycle of the available varie- pleasant for harvest. Rice maturing after the ties. Essentially it is the difference between the temperatures have lowered somewhat may be of lensrth of the ofrowino; season for rice in an area better milling quality. When rice matures during and the shortest ¡period of time rec|uired to ma- extremely hot weather, considerable sun checking ture a crop. may result and low head rice yields may be pro- Seeding time also is influenced, directly or in- duced when the grain is milled. directly, by favorable weather conditions for land Chambliss (18) stated that in the prairie areas preparation and seeding operations, methods of of Louisiana and Texas, most of the rice is sown seeding, fertilizer practices, availability of fresh from April 1 to May 15. However, he pointed water, temperature of water, cold tolerance of out that May 1 was approximately the best date varieties, and time of maturity of varieties in re- for sowing rice on the prairie because of the cold lation to date of seeding. weather that sometimes prevails during April. Adair and Cralley (5) stressed that the proper According to Jones and others (69)^ rice usually seeding date for each variety is important. They is sown in the Southern States from April 1 to stated that no rice variety should be sown until May 80. Rut if conditions are favorable, some the mean daily temperature rises to about 70° F. seeding is done in March and as late as June 30. They and Johnston and others (ö5, 66) reported Rice germinates more quickly when sown in the that because of the relatively long growing period late spring, when temperatures are relatively of several of the varieties then available, it was high, than when sown earlier. Also, late seeding necessary to seed these varieties in Arkansas by has an advantage in that the weeds that have late April or early May. Other, shorter season started growth can be killed by cultivation before varieties had a wider range of seeding dates. seeding of the rice crop. However, when any variety then available was Reynolds (Wo) stated that time of seeding rice sown in Arkansas after the first week in June, in Texas ranges from March 1 to late June but there was a risk that the crop might fail to ma- that most of the rice acreage is seeded in April ture if there was an early frost. However, with and ]\iay. He pointed out that the actual time the development of the very early-maturing var- of seeding may depend on several factors, such ieties Belle Patna and Vegold, mid-June seedings as the weather, method of seeding, soil condition, appear to be relatively safe, even in northern Ar- and maturity group of the variety. Some varie- kansas. Johnston and others (64) suggested that ties can tolerate cool weather in the spring better these two varieties be seeded in northern Arkan- tlum others and will thereby produce better stands sas from about June 1 to 10, in central Arkansas when seeded relatively early. He further re- from about June 1 to 20, and in southern Arkan- ported that the yield of certain varieties showed a marked decrease when seeding was delayed sas from June 1 to 25. Johnston, Cralley, and beyond certain dates. He concluded from tests Henry (66) emphasized that a relatively ^''safe^' at Beaumont that the late-maturing varieties seeding date may depend to a considerable extent should be seeded as early as practicable to insure on anticipated water management and fertilizer satisfactory yields. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 87 In California, the period for seeding rice is tion. On land that has been in winter or peren- more concentrated than it is in the South. Some nial pasture crops, a delay in date of seeding rice is sown in California soon after April 1 and provides a hunger grazing period and makes pos- some as late as June 15, but most of it is sown sible the preparation of a better seedbed. from April 15 to May 15 (36). When rice is Late seeding also has disadvantages. There sown as late as May 30 in California, it should may be a greater possibility of injury by root be fertilized at a moderate rate, and preferably maggots, armyworms, and stem borers. Weather a short-season variety such as Colusa should be conditions may be more favorable to the blast orrown. fungus at the time the young plants are suscepti- Very early seeding entails certain hazards sucli ble. Stem rot may be more severe late in the as loss of stands due to seedling blight or drown- season. The crop is exposed to early fall storms, ing out of drilled rice. Early growth is slow, likely to be the most damaging of the season. prolonging the period from seeding to harvesting. Cold weather may reduce quality and yield if Isolated early-maturing fields may be attacked harvest is extremely late. Isolated late-maturing by concentrations of insects, rodents, or birds. fields probably are more exposed to damage by Rice that matures early during hot and dry concentrations of birds and other pests than are weather tends to have lower milling cjuality. extra early fields. Relatively early seeding in the Southern States Clearly, there is no ideal time for seeding. In helps assure an adequate supply of water to Louisiana and Texas especially, where the seed- mature the crop before a summertime shortage of ing period is long and there are several varieties water or, in limited areas where it occurs, before to choose from, the date of seeding demands care- the intrusion of salt water. Water is available ful consideration. This is true whether one field for early-seeded rice in all areas, although in is to be seeded to a single variety or a large acre- California the water may be too cold. Earlj- age is to be allotted among two or more varieties. seeded rice may tiller more, may compete more effectively with weeds, and may escape insects and Rate of Seeding diseases to some extent. AA'lien rice can be har- Factors that enter into a determination of the vested early in the season, it usually is possible proper rate of seeding include seed size and qual- to avoid seasonal congestion at the driers and to ity, condition of the seedbed, fertility of the soil, find a ready market. Also, early seeding of short- date of seeding, and variety. In the southern rice season varieties usually allows time for the pro- area, the seeding rate is about 90 to 110 pounds duction of a stubble crop in southern Louisiana per acre when drilled and about 115 to 150 pounds and Texas. Because of the somewhat shorter per acre when sown broadcast on dry soil or in growing season and cooler fall temperatures, the water. In California, when rice is sown in results and observations indicate that such double the water, seeding rates average about 150 pounds cropping (ratoon cropping) is not a safe practice and range from 125 to 200 pounds (dry weight in Arkansas in most years (ßJ/.). basis) per acre. However, even the customary April seeding The number of rice seeds ranges from 14,000 to often is subjected to unfaworable conditions for 22,000 seeds per pound, depending on the variety. establishing stands. Varieties that have short With a seeding rate of 150 pounds per acre, seeds growing seasons mature during hot weatlier if are sown at the rate of about 50 seeds per square seeded at the average time, ancl in some seasons foot. Excellent yields have been obtained from the quality is poor. Localized summer wind populations ranging from 8 to 30 plants per storms and rainstorms may cause lodging with square foot. Seeding rates that provide plant resulting loss of yield and increased cost of populations between these extremes apparently combining. Often at the peak of the season more do not influence yields. Extremely dense stands rice is ready for harvest than the driers have lodge more readily than do optimum stands. Kice capacity to process, and the rice that waits in the in dense stands heads and matures more uni- fiekl is in danger of deteriorating. formly than does rice in thin stands with abund- Rice matures in a shorter time when sown late ant tillering. Weed control is more difficult in than when sown early. Delaying seeding or using thin stands, so seeding rates should be higher in varieties that require long growing seasons per- fields infested with weed seed. Relatively high mits harvesting to be done in the normally cool seeding rates usually are used on land on which autumn weather when there may be fewer show- many rice crops have been grown previously. ers and when the driers are less likely to be In early tests in Arkansas, Nelson (93) tried crowded. Later maturing rice usually is better 11 rates of seeding, using recleaned seed, seeded quality as long as the temperatures are not too with a grain drill. The results showed no marked low for normal development of the grain. De- preference for any rate. Although denser stands laying seeding also allows time for additional and fewer weeds were obtained from the higher cultivation to reduce weed and red rice infesta- rates of seeding, higher yields resulted from the AGRICULTURE HANDBOOK 28 9, U.S. DEPT. OF AGRICULTURE lower rates of seeding. The higliest average and sometimes may be reduced if more than 80 yields were obtained from sowing approximately pounds i)er acre is sown. They pointed out that 70 pounds of seed per acre. under ordinary conditions, 90 to 100 pounds of Simmons {115) reported that later studies recleaued viable seed sown with a drill or 110 to at the Arkansas Rice Branch Station at Stuttgart 150 ¡rounds sown broadcast is sufficient to give indicated that the best rate for drill seeding was good stands. They stated that the rate of seed- 90 to 110 pounds per acre and that about 110 to ing should be sufficiently high to produce stands 135 pounds per acre was best when the seed was that are thick enough to help check weed growth broadcast. and also to i^revent late tillering. The latter Chambliss [18), reporting on early experiments often results in irregular ripening and grain of at the Crowley, La., Rice Experiment Station, inferior quality. found that the largest yields and the best quality of milled rice were obtained from the Honduras Method of Seeding variety by drilling SO pounds of seed to the acre. SeA'eral methods are used to seed rice in the Other varieties available at that time could be United States. On dry soil rice may be sown fi/^ seeded at a slightly lower rate. He pointed out to 2 inches deep with a grain drill, or broadcast that less seed may be used when the crop is sown and disked or harrowed to cover. TVlien soil in late 3iay if the seedbed is well prepared, smce moisture is not sufficient for germination and better germination is obtained with higher tem- growth, the field may be flushed. The water is ¡Jeratures prevailing. The quantity to be sown drained immediately becau.se the rice seedling depends on the method of seeding, variety, char- cannot emerge through both 1 to 3 inches of soil acter of the seedbed, soil fertility, and vitality or germination of the .seed. If rice is broadcast on and 4 to 8 inches of water. Rice also is broadcast wet land or on a poorly prepared seedbed, the in water by airplanes (fig. 33). Several modifica- rate of seeding should be increased. If seed of tions of the water-seeding method are used. Rice low vitality is used, then the seeding rate should is not transplanted in the United States. be increased accordingly. Seeding at too low Simmons {115) reported in 1940 that the two a rate resulted in excessive tillering, irregular methods of seeding being used in Arkansas at the ripening, and reduced grain yields. time of his report were the broadcast and the drill Reynolds {105) stated that in Texas the rate of methods. The broadcast method had been most seeding ranges from 60 to 125 pounds per acre, popular since it did not require much machinery, with the average about 00 pounds. The rate of and it was u.sed extensively in new rice areas. He seeding varies greatly in different parts of the pointed out that drilling"was being used widely rice belt of Texas. In the more humid areas, higher rates of seeding are u.sed than m the west- ern counties where rates as low at 60 pounds per acre frequently are used. At Beaumont, from 1914 to 1918, seeding 100 pounds per acre pro- duced slightly higher yields of rough rice than seednig 60 and 80 pounds per acre. Experiments were conducted there from 1950 to 1952 to deter- mine the oi^timum rate of seeding rice under several levels of soil fertility. Bhiebonnet 50 was broadcast at rates of 45, 90, 1P,5, and 180 pounds per acre. Fertilizers were applied on the surface with a fertihzer-grain drill at the time of seeding There were no significant differences in the aver- age yields of rough rice from the seedino; rates of 90, 135, and 180 pounds per acre, but the yields from these rates were significantly higher" than those from the 45-pounds per acre rate As in earlier experiments, the optimum rate of seeding was about 90 pounds per acre. Where weeds are troublesome, heavier rates of seeding usually mve better results. ^ Jones and others {69. 70), summarizing rate of seeding experiments with drilled rice under iavorable conditions, indicated that 80 pounds of FiGTTRE 3.3.—Airplane being loaded with seed rice, with seed per acre usually is sufficient to give good tanlis u.sed for soaking seed in the foreground, and ricefields ready to be seeded on each side of landing stands. Yields are seldom materially increased strip. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 89 on old riceland. Advantages of drilling over and Hockley soils, than on clay soils, such as broadcast seeding were that less seed was required Beaumont clay and Lake Charles clay. for a good stand and that the seed could be put Iveynolds (105) pointed out that rice usually was clown at a uniform depth and rate, which make a seeded m Texas with a grain drill but that aerial more uniform stand possible. Simmons pointed seeding was increasing rapidly and that 110,000 out that uniform stands are important because acres were seeded by plane in 1953. He stated they insure even maturity. Grain maturing that broadcast seeders were used to some extent. evenly will have a better grade, and consequently On rough, dry seedbeds, rice frequently was will usually command a better price. lie further broadcast with endgate seeders or with a drill stated that when rice was seeded with a grain with the disks removed. In either case, the land drill, a depth of 1 to 2 inches normally should be was then harrowed after seeding and was irri- used. Deeper seeding sometimes resulted in a gated. When seeding was done on dry land, poor stand, especially if the soil was clay tex- fields usually were harrowed after seeding and tured, cold, or inclined to crust after rains. then flushed to bring about germination. The Jones and others [69) also reported that shal- fields were resubmerged in time to control the low seeding is preferable to deep seeding on a growth of weeds and grass. rough seedbed or a fine mellow seedbed that is The seeding of rice in water was started in inclined to crust after rain. Surface crusts may California as a way to control barnyardgrass be broken by a light harrowing or by irrigating (EchinochJoa spp.) (6). At first rice was sown to permit the seedlings to emerge. with a tractor-drawn endgate broadcast seeder, Xelson (94) reported in 1944 in Arkansas that but this method was not very satisfactory. Air- seeding rice broadcast on the surface of the soil plane seeding was attempted first near Merced, and irrigating immediately gave large increases Calif., in 1929, for reseeding a field of rice. A in yields of rice over the usual method being used fair stand of rice and a satisfactory yield were at that time. He pointed out that even larger obtained. Several growers in California seeded average increases in yield were obtained when the their rice from an airplane in 1930. Now air- soil was flooded and the seed broadcast in the plane seeding is the common practice on Cali- water. He indicated that both methods could be fornia's 300,000 acres of rice. used to produce higher yields of rice if the prac- According to Finfrock and Miller (S6)^ the tical difficulties involved in seeding large areas usual practice in California (19(31) is to soak the by these methods could be overcome. The yield seed for 18 to 24 hours in a sodium hypochlorite increase apparently was due to the control of solution (see ''Seed Treatment,*' p. 85), drain for grass. 24 to 1^ hours, and seed by airplane into fields Mullins (89) found that in Mississippi, where that have just been flooded to a depth of 6 to 8 ground equipment was common, rice was seeded inches. Seed rice will absorb the maximum after the first levee-building operation was per- amount of water in 18 to 24 hours. formed and before the levees were raised to the Soaked seed is used instead of dry seed. Soak- desired height. Seeding was done with endgate ing starts the germination process before seeding. seeders by approximately 50 percent of the farm- More important, because it is heaAW, the soaked ers who were surveyed, and grain drills were used seed sinks into place when it hits the water. Thus by the remainder of those using ground equip- the seed does not drift and unseeded areas are not ment. By 1958, about 20 percent of the farmers left in the field. Fields remain continuously seeded some rice in the water with planes, and flooded until drainage for harvest. the practice appeared to be more common in 1959. Modifications of water-seeding methods broadly Water seeding often was used during the later adapted to use in the sourthern rice area have weeks of the planting season when quick germi- been developed. Slusher (119^ 120) extensively nation and effective grass control are particularly discussed the use of aircraft to seed rice in important. Some farmers reseeded their levees Arkansas, after the final levee-building operation, but the Adair and Engler (6) described the water- majority did not. seeding method as used in Arkansas as follows: Reynolds (105) reported that a depth of 1 to 2 The land usually is plowed in winter and a seed- inches was best when rice was seeded with a grain bed is prepared in the spring by disking two or drill. In experiments conducted at Beaumont, three times and then harroAving. Frequently, the Tex., from 1914 to 1918, placing the seed 2 inches soil also is tilled to a depth of about 8 inches with deep produced slightly higher yields of rice than a field cultivator to provide aeration and space placing the seed 1 or 3 inches deep. There for applying cool irrigation water that contains usually was less rotting from shallow seeding than dissolved oxygen. Oxygen is essential for early from deep seeding, especially if irrigation was root development. The levees are completed after necessary to germinate the rice seed. Seed could the soil is worked with the field cultivator and be planted deeper on sandy soils, such as Katy the field is then cultivated between the levees with 90 AGRÍCULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE a spring-tootli harrow, which leaves shallow fur- much less than loss from weeds due to drahiing rows and ridges that help to reduce drifting of the field. the seed. The IcA^ees may or may not be seeded (5) After a period of 6 weeks or more, the before final going over with the levee disk. field may be drained for midseason nitrogen Floodgates are then put in, the field is sub- fertilization. merged to a depth of 4 to 6 inches, and the rice A few growers in Arkansas pregermmate the is sown from an airplane. Seeding is done as seed by soaking it before seeding. In one method promptly as possible, since poor stands usually the seed is placed in a grain cart such as that are obtained when the water has been on the used to haul the rice from the combine at harvest- field longer than about 4 days before seeding. time. The grain cart is filled with water, or The airplane operator is guided by flagmen, water is kept running through the seed for sev- one at each end of the field, who pace off the eral hours. Then the water is drained and the distance (about 30 feet) that the plane can sow rice is left in the grain cart overnight. The fol- in one trip across the field. Depending on the lowing day it is angered into the hopper of the length of growing season of the variety being plane for seeding. In another method the seed grown and the desires of the operator, the water is soaked in bags in a canal for a somewhat may be drahied from the field after 5 weeks or longer period, up to 3(3 hours. more to control the rice water weevil, to prevent Faulkner (34) compared different practices for straighthead, or to provide dry soil for topdress- water seeding rice in Louisiana. These included mg with fertilizer (6"). Occasionally, draining (1) pregerminated seed compared with dry seed, at an earlier date may be necessary. However, (2) cloddy seedbed compared with seedbed that unless specific conditions exist that require early had been smoothed in water, and (3) draining draining, it is advisable to drain late because irrigation water 3 to 5 days following seeding high grain yields have been obtained when flood compared with leaving a full flood of water and water was left on fields until shortlv before har- allowing the rice to emerge through the water. vest (93). He reported slightly higher grain yields when From tests with water-seeded rice on clay soil the seed was soaked to ])regerminate it before in Arkansas, Hall (SO) suggested the following: seeding in the water. He found that a small (1) A disk harrow is eff'ective in preparing the percentage of the dry seed floated in the water seedbed. On the last trip over, a spring-tootli and settled in low spots, whereas the pregermi- harrow should follow the disk harroAV so that nated seed remained well in place on both the prominent furrows are left in the seedbed to cloddy and smooth seedbeds. However, he catch the seed and reduce the drift. pointed out that pregerminating seed requires additional labor and expense and also requires (2) The field should be flooded as rapidly as a short interval between germination and seeding. possible with a minimum of 4 to G inches of Faulkner found that the average yield of rice water to control grass. All levees should have produced from the smooth or the rough seedbeds a gate or spillway so as to make and maintain was approximately the same. However, there a constant level of water and prevent the levees were some indications that the working of the from breaking because of added pressure from soil in w^ater reduced the germination of grass heavy rains. seed and thereby reduced the resulting competi- (3) The field should be seeded immediately tion. Also he found that soils that were worked after the 4- to 6-inch depth of water is obtained. in the water dried more quickly when the water In the test conducted, there was no significant was drained and caused the top one-fourth inch difference in plant stand densities obtained due of soil to curl, thereby pulling the young seed- to seeding in clear or in muddy water that lings from their root anchorage. Such conditions cleared within 24 hours after seeding. Likewise, would require that the area be flushed. presoaking the seed showed no significant differ- In this series of experiments, Faulkner found ence from seeding with dry seed. It was found that good stands of rice, along Avith excellent that seed treated with a fungicide or insecticide, control of red rice and grasses, could be obtained or both, had less tendency to float than did un- treated dry seed. by leaving a full flood of water on the field until the rice had emerged through the water and was (4) After seeding, the full flood of 4 to 6 strong enough to stand free from the water. inches of water should be maintained for 5 to 6 The yield results from 1959 indicated that about weeks. Lowering the water depth or draining 500 pounds more rice per acre was produced the field soon after seeding allows grass to be- \yhere the water w^as allowed to remain on the come established with the rice, thus defeating field than where it w^as drained a few days after the purpose of water seeding. A rate of 135 seeding. Faulkner thought that on the clay soils pounds of seed per acre gives a sufficient number it might be more difficult to obtain a good stand of plants, so that the loss due to wave action is of rice using the continuous flooding method, but RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 91 that additional experiments would be necessaiy utor is first used. From the deposit ]jatterns to determine this. obtained, optimum flagging intervals can be de- The most common method of land preparation termiiied that will allow for an overlaj) sufficient for water seeding in Texas in 1954, according to to maintain a uniform application or seeding Eeynolds (105)^ was plowing and disking to kill rate. For proper overlapping of swatlis, a the vegetation. The land was then left in a ground crew is necessary. For uniform distri- rough condition until seeding, at which time the bution a flagman should be stationed at eacli end field was irrigated until the water barely cov- of the field, and each flagman should be equipped ered the land. It Avas then liarrowed to muddy with two long markers comiected with a rope or the water. HarroAving to muddy the water be- chain length equal to the flagging interval dis- fore seeding is seldom done early in the season, tance. It is necessary that the flagging interval because dry north winds cause the soil surface be measured correctly and that the airplane fly to dry rapidly. This drying curls and cracks directly over the two flags. Recently, many the soil surface before the seedlings become growers have measured these flagging distances rooted. The seed usually was soaked in bags in or intervals and have marked them with stakes a canal for 24 to 36 hours, removed from the or small flags on wires so that the flagman will water and allowed to drain, and then sown by not need to measure the distance. airplane on the water. Some farmers drained their fields as soon as possible after sowing, Transplanting Rice whereas others might delay draining as much as Yields of direct-seeded and transplanted rice 36 hours. Experiments conducted by Wyche and were compared in a stud}^ conducted b}^ Adair Cheaney (150) during 1954 at the Rice-Pasture and others (7) in the major United States rice Research and Extension Center showed that areas during a 3-year period starting in 1937. under the conditions of the test, soaking the Tliree varieties were included in the experiment seed, muddying up the water, time of removing at three rice experiment stations in the Southern the water after seeding, and depth of the water States, and two varieties were included at the up to 8 inches had no eflFect on the yield of California Rice Experiment Station. High jàelds water-seeded rice. They felt that it would be a of transplanted rice often obtained under intense good farm practice to leave the surface of the culture in certain countries had led to a more or soil slightly rough in order to lessen the drift less common belief that yields of transplanted of seed vrhen water seeding rice. rice generally are higher than those from direct From observations made on experimental tests seeding. Advantages claimed for transplanting and on commercial fields, little if any difference were listed and discussed. It was pointed out in suitability to water seeding has been noted that high-quality, stiff-strawed varieties already among varieties. However, in Arkansas where were being grown by machine methods in several the soils are alkaline, or the water contains ex- countries. During the 3 years of these tests, the cess salts, the medium-grain varieties in general average yields of some of the varieties at some have been damaged less from these adverse con- locations were significantly higher from direct ditions when water seeded than have the long- seeding than from transplanting. None of the grain varieties, especially the Bluebonnet group. varieties at any of the stations produced signifi- Hall and Thompson (5T) pointed out that these cantly higher average yields when transplanted problem areas that are colloquially referred to than when directly sown. These workers con- as alkaline have been brought about, on culti- cluded that the principal reasons for transplant- vated lands, by the use of well water containing ing are not to increase 3àelds but to better use excess salts combined with restricted internal land and labor in densely populated countries in drainage of the soil. Some of these troublesome which the tillable land area is limited and the soils have shown a pH of 7.0 to 7.5, whereas labor supply is plentiful. others have been below 7.0. This indicates that pH alone is not a complete!}^ reliable indicator Irrigating and Draining of such problem soils. Flood irrigation is used for all rice grown in Nelson {92) conducted an investigation to de- the United States. The soil is submerged in 4 to termine the uniformity of distribution of seeds 8 inches of water most or all of the time from and fertilizers from airplane distributors and seeding or shortl}^ after, until the grain is nearly studied the extent to which rate of application, ripe. This period may extend from 60 to 90 or materials distributed, and flight altitude affected more days, depending on method of seeding and uniformity of distrilDution. He concluded that variety grown (5, 69). Although the water re- a fairly good distribution is possible with well- quirement for rice is high, Jones and others (69) designed equipment if a few precautions are fol-, stressed that good surface drainage is as neces- lowed. Characteristic deposit patterns should sary for successful rice culture as is a dependable be determined before a new or modified distrib- supply of fresh irrigation water. 92 AGîiI'!/'UUiVrUKE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE vary depending on amount of plant growth, solar Haskell (J¿) pointed out m HUn tliat a plenti- ful and easily a('eessil)le water su})])ly is tlie ñrst radiation, temperature, wind, relative humidity, requisite wliere rice is to be oTown. He also em- soil type, and rate of inflow of water into the phasized the importance of i)ro]:)er use of avad- field. " A rate of flow^ equal to 1 cubic foot per able water. He su<:<;-ested that under certain con- second (450 gallons per minute) for each 50 ditions, it was beneficial to control the fiow of acres being irrigated usually is required to main- fresh water so that it traveled the entire leno-fh tain watei^levels on ricefields in California (37). of each cut. This circulation resulted in more The apparently lower water requirement for uniform water temperature and liel])ed to con- rice in the Southern States as compared to Cali- trol alo-ae (scum) and insects. He also stressed fornia is related to naturally occurring climatic the importance of judicious water niana^i'ement differences in the évapotranspiration losses from in reducing the effects of certain diseases and ricefields between the two areas. Whereas the other production hazards. relative humidity during the growing season is cjuite higli in the Southern States, it is compara- Amount of Water Required tively low in California. In California, a vege- tation-free water surface will lose from 5 to 6 The water requirement of the Ignited States acre-feet in 12 months, whereas this loss in south- rice crop is comparatively high liecause the fields ern rice areas may be less than half this amount. are continuously flooded for so mucli of the grow- ing season. Rice will not produce a profitable Source of Water crop on stored soil moisture or infreijuent rains, It is estimated that 30 to 35 percent of the 1962 as will other cereals (8). When tried in the united States or when used elsewhere, the up- rice acreage in the United States was irrigated land system of rice culture generally results in from wells. iVdair and Engler (6) stated that yields of only ;><) to 7<) i)ercent of those ol)tained over 40 percent of the 1953 rice acreage received from flooded rice grown under similar soil and well water. Since that time, however, numerous climatic conditions. additional reservoirs have been constructed. Senewiratne ami Mikkelsen {IJ.Í) suggested Many of these reservoirs were constructed in that differences in groAvtli res])onses of flooded Arkansas. The reservoirs are filled with runoff and unflooded rice may l)e due to differences in water before the ricegrowing season. Other auxin metabolism. They found that plants grown important sources of irrigation water are rivers, under unflooded conditions had a low catalase bayous, lakes, and draiuAvays. activity and a high peroxidase activity, which Adair and Engler (6) discussed the early irri- favored accelerated auxin degradation. They gation of rice and reported that in 1894 the first suggested that high manganese levels in plants large irrigation plant was established near grown under unflooded conditions affect the in- Crowley, La. After failures of some pumps, a dolacetic oxidase meclianism and result in re- somewhat larger centrifugal pump was installed tarded growth and deju'essed grain yields. Kice in 1896. This pump delivered 5,000 gallons of grown with ammonium nitrogen (flooded) col- water per minute, which was enough for the rice lected small amounts of manganese, wliereas acreage planted at that time. During the next plants grown with nitrate nitrogen (typical of few years, many pumping plants were installed upland rice) contained much more manganese. on the streams in southwestern Louisiana and Clark, Neari)ass, and Specht ( j/), however, con- southeastern Texas. By 1901 some pumping cluded that ''the better growth of rice in sub- plants in operation delivered up to 45,000 gallons merged as compared to uidand culture in at least of water per minute. some soils is due to greater iln availability under Diesel engines came into common use for pump- submerged soil conditions." ing water after 1919 (6), Convenience, IOAV labor Jones and others {69) indicated that from 2.8 recpiirements, and reasonable initial and operating to 3.8 acre-feet of water normally was recjuired costs have since caused a shift to electric power to produce a rice crop in the Southern States. and natural gas power for irrigating rice. In About one-third of this is supplied by rainfall Arkansas in Í955, nearly 50 percent of the 1,800 during the growing season. Robertson (106) re- irrigation installations were powered by elec- ported from early observations that the total sea- tricity. In Louisiana, of a total of 1,06Í wells, sonal use of water for rice in California normally 450 were powered by diesel engines, 212 by na- ranged from 4.3 to 14.8 and averaged 8.2 acre- tural gas, 105 by electric motors, and the re- feet. After a ricefield is flooded, a considerable mainder by other units. In some cases water is amount of water is required to maintain an opti- pumped or relifted by means of the power take- mum depth in the field. Water is added periodic- off unit on tractors. ally to conqjensate for losses due to transpiration Historically, most areas in the world where by plants, evaporation from the water surface, water is pumped from wells have experienced deep percolation, and spillage. These losses will declining water tables. This problem, as related RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 93 to Arkansas nee production, was studied by Speciiic Electrical Conductivity Engler, Thompson, and Kazmann {30), Sug- (K A 10«) 1 less than 750 gested remedies included the use of deep weíls Boron, parts per million lesstlian 1 (900 to 1,000 feet) that normally supply more S.A.K. index (tendency to form water than shallow wells (100 to' 150 feet) and ^alkali soil) I less than 10,0 the use of small reservoirs. Engler {;29) reported When high sodium \vater is regularly used that during a oO-year period, the decline in Avater each growdng season, it may deflocculate the soil, level for the Grand Prairie area of Arkansas so that stickiness, compactness, and impermea- averaged about three-fourths foot per year, which bility increase. The deflocculated soil is difficult caused an annual decline in capacity of shallow to r'ultivate and usually produces IOAV yields. wells of 20 to 25 gallons per minute. Various Pearson {96\ 97) described the point of great- methods of replenishing underground water sup- est importance as the nature of the soil solution plies on the farm are discussed by Muckel (57). or saturation extract found in the zone of rice GerloAv and Mullins (4-) pointed to the value roots. If soil saturation extracts have a conduc- of small, 20- to 40-acre farm reservoirs in con- tivity index of 4 to 8 millimhos, the yield of serving surface runoff water to supplement or Caloro rice may be reduced 50 percent. replace well water for rice irrigation. Another Rice is very tolerant of salt durino- irermina- development designed to conserve water (whether tion, out rice seedlings are very sensitive to salin- from wells or elsewhere) has been the increasing ity during early development (1 to 2 leaves) and use of underground concrete or Incite irrigation are progressively less so at 3 to 6 w^eeks of age pipelines (laid about 30 inches beneath the soil [96, 99). When soils are strongly saline, having surface) to transport irrigation water for rice an excessively high concentration of sodium, cal- and the accompanying rotational crops. Pipe- cium, or potassium, the concentration of salts in line irrigation greatly reduces the rodent damage tlie soil solution (including the standing water) that characterizes open irrigation systems. In may be so great that it wdll injure or kill the addition, it greatly reduces evaporation and seep- seedling rice (98). Excessive salt concentration age losses. Aside from the important aspect of results in restriction in dowui^vard percolation; water conservation, it has been calculated that, therefore, the flood water is subject to a longer for each 1,000 feet of open canal replaced with a period of evaporation wdth an ensuing increase pipeline, 2.S acres of land are returned to crop in salt concentration. Thus, w^ater having: a production (3), higlier salt concentration enters the soil, and the Adair and Engler (6) pointed out that pump- salt concentration of tlie soil solution is increased. ing from bayous supplies most of the surface water in Louisiana and Texas. According to Adair and Engler {(J) reported that salt wa- Anderson and ^NIcKie (Í7), sources of rice irriga- ter ]uit on dry soil damages a ricefield more than tion water in Mississippi are shallow^ "wells (90 if salt water is used to replenish the water sup- to 100 feet) and surface water from lakes or ply in a field that has been watered with fresh streams. Diversion from large streams is the water. The reason given was that the salt was main source of water for rice irrigation m Cali- more concentrated in the dry soil, and more of fornia. It is estimated that less than 5 percent it moved into the root zone, where it ^vas taken of the California rice acreage is irrigated from up by the plants. They indicated that rice wells. grown on clay soils may not be injured as much by salt water as is rice grown on lighter soils, Quality of Water because less water is used and less is lost by seepage. For successful rice production it is very import- ant that the available water be of suitable quality. The rice plant can tolerate higher concentra- Sice irrigation water should be relatively free of tions of salt in the later stages of growth, al- dissolved salts that are toxic to rice plants. The though veiy high concentrations may kill the characteristics of irrigation w^ater that determine plants or make them sterile. Some varieties of quality include (1) total concentration of so]u))le rice are more tolerant to salt than are others salts; (2) relative proportion of sodium to other and may make satisfactory yields when the wa- cations; (3) concentration of boron or other toxic ter contains salt concentrations of 75, 150, 200, elements; and (4) under some conditions, the and 250 grains per gallon in the tillering, joint- bicarbonate concentration as related to the con- ing, booting, and heading stage, respectively. It centration of calcium plus magnesium. Other is Ijelieved that some of the newer varieties hnportant factors to consider are the initial salin- Avould be damaged seriouslv bv such amounts of ity of the soil, the effect of internal drainage on salt(ö). the flooded soil, and the total salt content of the Irrigation water pumped for rice from shal- soil. Finfrock and others {37} described good- low Avells in Arkansas and other States fre- quality rice irrigation water thus: quently has a comparatively high sodium con- ULTURE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE 9^ MWÄ tent as compared with water coming from surface ter low in total salts, the plants soon recovered. streams. Kapp (71) suggested tliat the source Water low in total salts w^as used for the re- and chemical composition of rice irrigation wa- mainder of the season, and a normal crop of ter should be considered from both the imme- grain was produced. diate effect on the current crop and the long- In California, rice culture has proved useful range productivity of the soil. In greenhouse in reclaiming saline soils, provided the fields to and field experiments he found that sodium be reclaimed are first engineered to drain well. chloride added to rice soil injured germination Mackie (77) reported that one rice crop grown and resulted in lowered production of vegetation m Imperial clay near Imperial, Calif., reduced and grain. The addition of 5,700 parts per mil- the saline content 72 percent to a depth of 6 feet. lion of sodium cliloride to the soil only slightly In his experiments he found the usual reduction reduced vegetation, but completely prevented in saline content from the first rice crop to be grain formation. In field trials, 825 pounds of one-third to two-thirds. Overstreet and Schulz sodium chloride per acre hindered germination, (95), in a series of San Joaquin Valley tests, and 3,300 pounds per acre reduced rice gram concluded that rice culture serves as an efficient yield. means of reclaiming nonsaline soil containing 15 Water from the shallow wells in Arkansas percent or more of exchangeable sodium. containing 75 parts per million calcium and 22 parts per million magnesium has caused some Water Temperature and Oxygen Content riceland soils to increase in alkalinity from an The temperature of water with which rice is original pH of about 5.0 up to as high as 8.0. irrigated has a profound effect on the plants. The change from a highly acid to a highly al- Adair and Engler (6") reported that the tem- kaline reaction is due to the annual addition of perature of rice irrigation water pumped from about 1,500 pounds per acre of limestone equiva- wells and from streams frequently is 65^ F. or lent. The increase in alkalinity has lowered the lower. When such cool water goes directly into availability of phosphorus in the soil. If a new the field, the rice growing near the water inlet source of water low in dissolved minerals is ob- usually is retarded and may ripen as much as tained, such changes may be reversed (ö). Such 7 to 10 days later than the rest of the field. water may be obtained from installing a deep Kaney, Hagan, and Finfrock (103) showed that well or constructing a reservoir and catching sur- with the building of high dams on the major face runoff water. However, as long as the un- California streams, the temperature of water favorable soil condition exists, delaying the ini- available for rice irrigation from surface streams tial flood and following a routine of alternate had dropped to 51° or less. draining and reflooding at 4- or 5-da3^ intervals until the plants are about 6 weeks old haA^e given The temperature of the irrigation water should fairly satisfactory relief in Arkansas. be not less than 70'' F. nor more than 85° for When the rainfall is below normal in the best results. Raney (102) showed that the crit- Gulf Coast area of Louisiana and Texas, the ical seasonal threshold of water temperature for water level in the streams that supply irrigation normal growth of Caloro rice Avas near 69°. water often is so low that brackish water en- When the mean temperature was 5° lower, ma- croaches from the Gulf. The concentration of turity was delayed 30 days beyond the normal chloride salts may become so high that the yield 160 days. Rice yield was highest when the mean and quality of rice is reduced or the crop is water temperature was 80°. At water tempera- ruined. Adair and Engler (6) pointed out that tures aljove 85°, yield was reduced and root de- several workers had shown that water contain- veloi)ment was poor, probably because of low ing more than 35 grains of salt per gallon (600 oxygen content of the water. parts per million) should not be used to irrigate Chapman and Peterson (£0) studied under- young rice if the soil is dry and if the water is water rice seedling establishment in relation to to remain on the field. Rice watered continu- temperature and dissolved oxygen. Under lab- ously with water containing 35 and 75 grains of oratory pot culture they found water tempera- salt per gallon was reduced in yield about 25 and tures in the range of 77° to 8-t° F. most favorable 70 percent, respectively, and the rice was of for the effective establishment of rice in static lower quality than when water containing only culture. Emergence of the shoot from the water 25 grains per gallon was used. was most rapid at 8J:°, but the development of Water quality in California ricefields was stud- the root system and the penetration of the soil ied by Stromberg and Yamada (135). They were favored by temperatures as low as 68°. found that water that contained a high total of Exposure to a water temperature of 104"° for soluble salts killed rice plants. However, when 12 hours or more was lethal to pregerminated a field showing initial symptoms of dying was Caloro rice seed. They concluded that it seemed immediately flushed out with quantities of wa- unlikely that dissolvecl oxygen deficiency would RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 95 ^.k .j,»* -*>«* fc.. H^^' ^^'. ^;^* "j*f*,>i»-. „ ^ - FiGUBE 34.—Headgate that controls flow of water from canal into ricefield. be a limiting factor in seedling establishment in water-warming basins, 6 to 12 inches deep, equal the field even at 95°, if currently recommended in size to 2 percent of the area to be served, seeding rates were used and the water had an successfully and economically raised the mean initial oxygen content of at least 5 to 6 parts per water temperature of 60° to 70°. million. Ehrler and Bernstein {28) reported that at a Water Control Methods constant root temperature of 64.4° F., Caloro shoot growth was twice that at 86° and root Methods of transporting and controlling irri- growth was one and a half times as great; how- gation water for rice production have evolved ever, grain yield was only three-fourths as much over the years. They vary in different rice- at the lower root temperature. No significant producing areas but tend to follow a general interaction was found between root temperature pattern. and cationic concentration or cationic rates. In most cases water is conveyed from the Seeds germinate slowly when the temperature pumps, streams, or reservoirs in canals from is less than 70° F. Water now available for rice which it is diverted into laterals, into field irrigation in some areas, including northern Cali- ditches, and finally into the field checks or pad- fornia, may be colder than this, ranging down dies. Water is usually delivered to the highest to 51° or less. Such cold water will retard and point in the field by canals or pumps. It passes lower the germination of rice sown in the water into successively lower paddies through metal and will retard the development of plants so that levee gates or levee control boxes or openings in the stand may be thin and crop maturity will be the levees. These gates or boxes provide perma- delayed near the inlet to the field. According to nent control of maximum water depth in each Raney, Hagan, and Finfrock {103), field studies paddy. over a 3-year period showed that plant-free Water that overflows or is drained from the AGRICULTURE HANDBOOK 28 9, U.S. DEFT. OF AGRICULTURE 96 rice area, metal levee gates with acljustable pan- lowest paddy may be caught in drainage ditches els are in common use in some localities (fig. 35). or canals and recirculated or moved into other Variations that may be used include single planks canals or drainage ditches. Some fields have a or boards or metal panels which are forced into canal along one side so that each paddy can be the soil across a narrow cut through a levee to watered separately from this canal. Finfrock keep the water at the desired level. In Califor- and others {37) described in detail the rice irri- nia, the levees are usually considerably larger o-ation control structures used m California. than those in the Southern States. The wooden ^ CANAL GATES.—Gates in the irrigation canals of the California ricegrowing areas are simple or metal boxes are placed along the more acces- sible side of the field. Flash boards of various structures of wood or concrete (fig. 34). In the vertical fixed portion of the structure, slots are widths are added or removed to regulate the provided so that short planks (flash boards) can water to the desired depth. Boxes must be be inserted or removed as desired to raise or properly constructed and installed so they will lower the water level at the diversion point into not be washed out (fig. 36). the field. Inlet structures to the field may con- DEPTH STAKES.—To gage the water level in a sist of similar slotted wooden structures or screw- paddy or check, a depth stake is driven into the type metal gates. The latter commonly are used soil within a suitable distance of the levee box in the southern rice area. or gate. The stake is set so that the bottom of LE^^EE BOXES OR GATES.—Water is controlled an 8-inch red band is at the average elevation within the field with boxes or gates set at con- of the ground surface in the paddy. If a 5-inch venient locations in the levees. In the southern flood is desired, then 3 inches of the red band is •y?»^> FIGURE 35.—A ricefleld in Arkansas that is irrigated and readj' to be seeded, showing the gates used to regulate the flow of water from one check to another. (Photo by Copeland.) RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 97 trapping or poisoning the pests. In California fields where the large levees sometimes are in- habited by crayfish and muskrats, the problem has been solved by using sheep to graze the ^..-»Ç%* vegetation from the levees. Water Management The application and management of water is a key operation in rice farming (89). The princi- pal functions of water cover are to control weeds, to condition the soil and provide a favorable environment for rice growth, and, especially in California, to serve as a temperature regulator by minimizing the effect of the large variations be- tween daytime and nighttime air temperatures. Systems of water management for rice produc- tion vary widely, depending on method of seed- ing, soil type, climate, crop rotation, diseases, and insects. A very important aspect of water man- PiGTiEE 36.—Levée box used in California to regulate flow of water from one check to another in ricefleld. agement is good drainage. This includes drain- age of winter rainwater as well as periodic drain- age during the growing season. In years when left showing. The stake is painted white at the riceland is used for rotational crops, the crops top, so that if an 8-inch flood is desired, only the may be drowned if drainage is poor. Seedbed white band is left exposed. preparation and fall harvest can be expedited by Construction of access roads around ricefields a good drainage system. Drainways around and helps to (1) cut production costs because equip- through the field that connect with main drainage. ment can be moved more easily into the field; ditches leading to natural drainage channels are (2) control water better and more economically : essential. These ditches should be large enough and (3) control mosquitoes by reducing seepage and deep enough to allow the removal of large problems, by making it easier to control weeds quantities of water quickly. When it is necessary where mosquitoes breed, and by enabling mos- to preirrigate or to flush irrigate to bring about quito abatement employees to reach troublesome emergence of rice, good drainage plays a key role spots. in getting a good stand quickly by expediting PROTECTION OF IRRIGATION SYSTEM.—Once they fieldwork and reducing seed rot losses (5, 69). are engineered and installed, riceland irrigation Good drainage of ricefields and adjacent areas and drainage structures are subject to damage and ditches also is of prime importance in elimi- from use, the elements, and insect or animal nating mosquito-breeding areas. pests; but countermeasures can be employed. In Essentially there are two broad systems of large, flat paddies or checks, wind levees may be water management, depending on the method of constructed between the normal-interval levees to seeding. The first broad system of water man- decrease wave action. Their judicious place- agement revolves around drilling or broadcast ment in areas subject to strong winds may be seeding on "dry" ground. Where necessary, seed- very beneficial. So-called alkali levees built ing is followed by flushing to bring about uni- from soil high in sodium and other salts fre- form emergence, and the first flood is applied quently are subject to washouts or breaks when later. This system is often used in the southern fields are flooded. Heavy applications of gyp- rice area. With the second broad system of water sum on such areas before pulling the levees help management, fields are flooded just before aerial to stabilize the soil and greatly reduce the chances seeding and usually remain flooded until they are of breaks. Plastic sheeting or various types of drained for harvest. This system is used in Cali- laminated paper also ,can be used to cover weak fornia, and with modification also is used in the areas in levees. Soil is plowed or shoveled onto southern rice area. In the southern rice area the edges of the material to prevent its floating (especially in Texas), where rice is water seeded when the field is flooded. Certain pests, such as on heavy soils, some growers drain as soon as muskrats, field mice, Norway rats, crayfish, and possible after seeding; others may delay draining large insects, often inhabit canal and drainage for 36 hours. After stand establishment, irriga- ditchbanks, as well as contour levees. Their bur- tion practices are essentiallj^ the same as for rowing? may result in levee or bank leaks or drilled rice (8). breaks and heavy water loss. Major structures, Unless rice is water seeded and the flood is such as weirs, can be protected to some extent by maintained, a flood is applied about as soon as the 98 AURIC ULTÜTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE crop is old enough to withstand submergence. As LOUISIANA.—Jenkins and Jones (62) found a means of Aveedy grass control, ricefields on the that in date-of-submergence experiments in Loui- lighter soils in Arkansas often are flooded as soon siana, the highest average yields were obtained on as the rice has emerged. If the fields are free of land submerged 20 days after the seedlings had weedy grasses or if these grasses have been emero-ed. In a discontinuous and continuous sub- chemically controlled, the land may not be sub- mergence experiment, early continuous submerg- merged until the rice seedlings reach a height of ence (10 days after seedling emergence) of the 4 to 6 inches. Jones and others (69) indicated land gave higher average yields than did inter- that at this stage the land is submerged to a depth mittent drying of the land followed by continuous of 2 to 4 inches. As the plants grow taller, the submergence. depth of water gradually is increased until it In Louisiana, water seeding is not common; but reaches 4 to 6 inches. During the rest of the where it is practiced, the water is drained when grooving season or until the land is drained before the rice seedlings are one-half inch long, accord- harvesting (except for special reasons), the water ing to Wasson and Walker (14^). It then is may be held on the land at a depth of about 5 allowed to groAv until flooding is needed. Drilled inches. To maintain this constant depth, addi- rice may be flushed if necessary for uniform ger- tional water should be applied to replace that lost mination. Normally the rice is not flooded until by evaporation, transpiration, and seepage. it is 6 to 8 inches tall, and then only to a depth Eeasons for draining ricefields during the of 41/4 inches. Fields are drained as necessary growing season and allowing the soil to dry in- for topdressing with fertilizer and for pest clude (1) control of algae (scum) ; (2) control of control. rice water weevil; (3) prevention of straighthead MISSISSIPPI.—Mullins (S9) stated that rice in (blight); (4) control of aquatic weeds such as the delta area of Mississippi is kept flooded for mudplantain (ducksalad) ; and (5) application 90 to 120 days during the growing season, depend- of nitrogen fertilizer. On saline or alkaline soils ing on variety and seeding date. The first flood it may be necessary to drain fields several times is applied as early as possible after the rice seed early In the growth of the rice to allow the plants germinates and a stand is established. This may to become well established. be about 2 weeks after seeding or, if germination ARKANSAS.—Adair, Miller, and Beachell (8) is slow, possibly 3 weeks after seeding. Applica- reported that water management is similar in tion of the first flood requires close attention to Arkansas and Louisiana. Depending on grow- avoid breakage of levees and to stabilize the water ing conditions and grass control methods being at the desired level. If the levees are accurately used, the first flood may be applied as the rice is located and well constructed, relatively little time emerging, or it may be delayed for 2 or 3 weeks. is required to apply the first water; otherwise, The majority of ricegrowers in Arkansas drain labor requirements may be much higher. Mullins their fields about midway in the growth of the reported that most fields were drained after 3 to rice and allow the soil to dry before applying 4 weeks under flood and the soil was allowed to nitrogen fertilizer. The fields are then reflooded, dry for several days. This permitted the roots and observations indicate that nitrogen is taken of the rice plant to become more firmly estab- to the rice roots as the water soaks into the soil. lished and also stimulated additional tillering. This results in more efficient use of the fertilizer. He suggested that if grass was well under control Hall (50) described the water-seeding method at this time, fertilizer could then be applied. used by some Arkansas growers. Seed is broad- TEXAS.—Reynolds (105) stated that where rice cast by plane into fields immediately after the is seeded with a grain drill on heavy soils, the application of 4 to 6 inches of water. The flood fields usually are flushed (irrigated) for germina- may be held for about 6 weeks before draining for tion if water is available and if the soil has not the midseason application of nitrogen fertilizer. been saturated by rain. Flushing usually is Other growers may drain their fields soon after practiced in areas irrigated from canals, since the the seed is sprouted and reflood after a few days. fields can be covered rapidly. Sandy soils and If fields are left drained for several days, heavy soils irrigated from wells usually are not flushed. stands of grass weeds may become established. After fields are flooded, irrigation water may be When rice is water seeded on heavy clay soils, drained off once or twice during the growing this early draining is a common practice. The season to permit fertilization and to control water fields then are reflooded after about 3 days and weeds and insects. The time and number of the flood is maintained until midseason. drainings may vary, depending on the length of In a series of greenhouse experiments. Hall maturity of the variety, the presence of weeds (49) found that unless rice plants were fertilized, and insects, and the supply of irrigation water. the practice of draining and drying the soil and Where there is a shortage of water for reflooding, then reflooding did not increase grain produc- the fields usually are not drained. If irrigation tion on soil low in organic matter. is required to germinate the seed, the field is RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 99 promptly drained after this flushing. Where rice hold the water on the land long enough to permit is seeded with an endgate seeder, the Land is then the rice to reach proper maturity. harrowed and irrigated and the irrigation water The time to drain depends on the type of soil, is drained off shortly thereafter. It has been drainage facilities, and seasonal weather condi- found from tests and general observations that tions. Some soils dry and crust quickly after satisfactory rice stands-are not obtained if seeds drainage; others dry slowly. Less time is re- are covered by both soil and water, so that drain- quired to dry the soil early in the season when ing water from fields where the seed is covered temperatures are higher and the days are longer with soil is extremely important. than is required later in the fall. Growers soon Morrison (85) found little difference in the rice familiarize themselves with the drying time of yields at Beaumont when the total amount of their soil, so that they can judge when to drain water used ranged from 46 to 73 inches. He con- the fields to permit harvesting and yet not let the cluded that the use of 45 to 50 inches of water crop suffer for lack of soil moisture. would be just as satisfactory as the use of larger amounts. These results generally agree with Usually the land may be drained when the rice those reported by Jones and others {69), It was is fully headed and the heads are turned down further concluded (85) that the depth of water and are ripening in the upper parts. This stage does not seem to be of much importance where ordinarily will be about 2 to 3 weeks before the weeds are not a problem. Draining ricefields once crop is ready to cut. The date when the rice will during the growing season increased the yield of be ready for harvest can be estimated by observ- rice considerably. ing the date of first heading (when approxi- Evatt (31) reported that preliminary tests con- mately one-tenth of the rice heads have emerged). ducted at the Rice-Pasture Research and Exten- Rice in the South normally requires 35 to 45 days sion Center in 1956 and 1957 showed significantly from first heading to maturity. In California, reduced rough rice yields of the Century Patna 231 crops of average yield will be ready for harvest variety with use of deep water (10 to 12 inches), about 45 days from the first heading. Heavy compared with use of average depths of water of crops with yields of 5,000 pounds or more per acre may require as many as 55 days from first from 4 to 6 inches from late tillering to maturity. heading to maturity. He found that the temperature variation was 2 to 4° F. greater under the shallow water than under Water intake should be discontinued a few days the deep water. Yields from superimposed fer- before final drainage. The water already on the tilizer factorials showed no significant fertilizer- field will then recede slowly. This lessens lodging water depth interactions in 1956. However, in and does not overtax the drainage system with 1957 yields were less from both nitrogen and excessive water. In the South the field may be phosphorus treatments under the deeper water. drained by removing the levee gate panels or by CALIFORNIA. —In California where japonica- "cutting" the comparatively small levees with derived varieties predominate, ricefields normally hand shovels. Levee gates sometimes are upended are rapidly flooded to a depth of 6 to 8 inches just or may be removed from the fields before harvest. before seeding. Then they are seeded with pre- Dynamite is used quite extensively in California soaked seed immediately after flooding to enable for opening levees to permit draining of ricefields the developing young rice plants to compete effi- before harvest. The levees are blown where they ciently with soil organisms for available oxygen cross the drains that are installed within the and with weeds for space and nutrients (36), fields. The dynamiting, which requires experi- The water is maintained at that depth until it is enced powdermen, is started at the lower end of drained for harvest. Water may be lowered to the field. about a 3-inch depth for weed control and at stand-establishment time during cool weather. Harvesting, Drying, and Storing If the soil in the field contains excessive amounts of salts, the water may become sufficiently saline Harvesting as to be toxic to the rice seedlings. In such cases Most rice grown in the United States now is the water may be drained from the field and fresh directly harvested with self-propelled combines. water applied immediately. The continuous flood It is then dried artifically before storing or mil- system comonly used in California was developed ling. A small amount of seed rice is cut, swathed, to control weeds, principally watergrass, and to and threshed from the windrow when the seed fit the fertilizer requirements of rice (55, 83). has dried down to 12 percent moisture or less. Draining for Harvest Direct combining and artificial drying is the most efficient and economical way of harvesting Draining at the proper time before harvest is rice. Careful adjustment of the combine and necessary to dry the soil enough to sup^Dort har- proper drying methods result in grain having vesting equipment. It is equally important to highest milling quality and commercial value. 100 AGRICULTURE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE Before adoption of direct combining, the or elevator. One such crew usually could harvest United States rice industry used three other har- about 16 acres of rice per 10-hour day. vest methods, according to Smith {12Ji)> These, Mullins {89) emphasized that the time required in order, were (1) harvesting by hand with a and the cost of harvesting depend largely on the sickle or cradle, and then stationary threshing; weather at harvesttime. Heavy rams and wind (2) cutting with team-drawn or ultimately with often cause excessive lodging and create unfavor- tractor-drawn grain binders, handshocking the able surface conditions for operating combines bundles, and then engine-powered stationary and other equipment. Severely lodged rice may threshing; and (3) cutting with a tractor-drawn be harvested with combines that have adjustable header or swather, followed by threshing from pickup reels. When this is necessary, the combine the windrow (when the grain was dry) with a must be operated at a much lower speed across a pickup combine. field, which greatly increases the time required Direct combining was first tested in Arkansas for harvesting. and Texas in 1929 {1'26). According to Bamer In a study of a large number of samples that {13), approximately 3,000 acres of rice were har- included the effect of method of harvest on rice vested by combines in 1929 m California, and mill yield and grade, it was concluded that there nearly 35,000 acres in 1931. The combined har- was little difference between the combine method vester-thresher had been developed primarily for and the binder-thresher method of harvest as it wheat, and the first models were not well suited related to the market value of the rice obtained. to ricefield conditions. Low wet spots, weed Most rice now is handled in bulk {122), al- patches, and high, narrow levees made combine though some, especially that being saved for seed, harvesting difficult. still is sack dried. The conversion from sacking At the same time that combine harvesting was rice in the field to bulk handling was accentuated first being tried, tests were being conducted on by increasing costs and scarcity of sacks and hand artificial drying of rice {126). ^ Even with the laboi". problems encountered in combining and artificial Today the self-propelled rice combine har- drying of rice, numerous advantages were cited. vesters are equipped with relatively large bins or These included: (1) In one operation rice is re- hoppers for collecting the threshed grain (fig. moved from fields with no danger of weather 37, A ). The hoppers then are emptied by mechan- damage; (2) very little loss of rice is sustained ically augering the rice into self-propelled "bank- through shattering; (3) rice of high milling outs" or tractor-drawn carts that take the rice to quality can be obtained regardless of weather waiting field-side trucks (fig. 37, B), Rice then conditions at harvest; and (4) all the rice can be is hauled to driers (figs. 37, C and 37, D) or to thoroughly and uniformly dried, making it safe aeration bins (fig. 38) where it is unloaded by use for storage either in bulk or in sacks. Also, it of grain augers or other bulk-handling methods. was pointed out that artificially dried rice usually Hurst and Humphries {61) discussed harvest- is more uniform in quality because of the thor- ing of rice with combines and pointed out that ough mixing during the drying operations. care should be taken not to crowd the feed. Be- Additional advantages of the combine method cause rice straw is heavy and green at harvest, the over the binder, as pointed out by Slusher and ground speed of the machine should be slow Mullins {121) were (1) the elimination, to a large enough to avoid clogging. Since the rice kernel extent, of the need for outside labor for harvest ; is very susceptible to cracking, the cylinder should (2) less chance for loss from destructive wildlife, be run at a slower speed than for other cereal principally blackbirds and ducks; (3) possibility crops. Allowing a small percentage of kernels to of salvaging a much higher percentage of crop in crack maj^ be necessary to thresh out a maximum case of storm or wind damage; and (4) report- yield. edly less field loss. These authors found that Special self-propelled rice combines used in hand labor used in harvesting was reduced from California are equipped with crawler tracks that slightly more than 11 hours per acre with the enable the machine to cross wet spots, small binder to from 2.4 to 3.6 hours with the combine ditches, and low levees. In rainy seasons, wide method, depending on the size of the machine wooden mud cleats are bolted on to the tracks to used. They reported that 400 acres of rice ap- increase the support for the harvester. Self- proaches the maximum seasonal acreage that a propelled combines used in the ricefields in the grower can safely plan on harvesting with one South usually are equipped with large tires with 12-foot self-propelled combine. Slusher {120) mud lugs so that they can be operated over the indicated that the usual crew for the self-pro- sloping levees. pelled combine method consisted of one man on In recent years, specially designed rice com- the combine, one man with a tractor and grain bines have been built by the major farm ma- cart to haul grain from the combine to the truck, chinery manufacturers in the United States and and two men and trucks to haul grain to the drier are being used in the ricefields of the South and RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 101 FIGURE 37.—A, Cutting and threshing rice with a combine harvester that is loading the rice into a "bank-out" or grain cart ; B, transferring the rice from the "banli-out" into a truclc in a road at field side : C, trucks loaded with rice waiting to unload at a farm drier ; Z>, unloading the rice at the drier. the West. These high-powered machines com- The effect of combine adjustment on harvest monly have 12- to 16-foot headers and can be losses of rice was studied by McNeal (79). He operated under extremely muddy conditions. found that there were four types of combine losses They can be adjusted to do a thorough job of —cutter bar, cylinder, rack, and shoe. To obtain threshing with a minimum of shelling and crack- maximum grain yields, it was necessary for the ing of the grain. Most combines now are cylinder bars and the concave to be in good con- equipped with straw choppers, which cut up the dition and for the concaves and other parts of rice straw as it leaves the combine, and a dis- the combine to be properly adjusted. He con- tributor, which spreads the straw particles uni- cluded that combine ground speed should be re- formly over the stubble to facilitate plowing duced to one-half mile per hour when the rice under. is badly lodged. He indicated that the operator 102 AGRICULTURE HANDBOOK 28 9, U.S. DEFT. OF AGRICULTURE ripe, the kernels may check. This causes severe breakage during combining and milling and a reduction in the yield of head rice (whole ker- nels). Smith and others emphasized that when rice has reached the proper stage, harvesting should proceed rapidly, since loss of moisture in standing rice may be very rapid. In rice har- vested at the proper stage, the grains were fully mature in the upper portions of the panicle and in the hard-dough stage at the base. Few, if any, chalky kernels were found in rice harvested at this stage of maturity. When such rice was prop- erly dried, germination was satisfactory for seed purposes. Bainer {13), Davis {26), Rester {72), McNeal FiGTJEE 38.—Bin drying combined rice on the farm. {80), and Smith and others {125, 126, 127) have reported results of research relating sta^e of is the most important factor in preventing higli maturity (moisture content) of the gram to combine losses. The height at which the rice was proper ' harvesttime. Although their findings cut was very important, since the proper amount varied, they were in general agreement that maxi- of straw served as a cushion to the grain in the mum yield of head rice was obtained when rice threshing process, and resulted in a lower cylin- was harvested at a moisture content of about 18 der loss and less hulling and breakage. to 24 percent and then immediately dried to be- tween 13 and 14 percent. Curley and Goss {^2) found that combine Varieties differ in the range of harvesttime losses also may be due to overloading or improper moisture content at which they yield the best machine adjustment or a combination of the two. quality milled rice. McNeal {80) reported that Overloading as a result of excessive ground speed a range in moisture content of 16 to 22 percent usually is the major cause for excessive loss in all provided the highest yield of head rice for Rex- sizes of combines. ark and that a range of 17 to 23 percent provided Their tests in rice indicated that total combine the highest yield for Zenith. Davis {25) reported loss including reel shattering should be less than that the best range for Caloro was 20 to 25 per- 5 percent of the gross yield if the machine is cent, and Kester {72) and Rester and Pence {73) properly adjusted and operated. Thus, the loss reported that the best range for Calrose was 22 to from a 6,000 pound per acre yield should not 27 percent. Their work showed that for every exceed 300 pounds. A high loss of unthreshed 1-percent reduction in kernel moisture while the grain usually resulted from improper cylinder or unharvested grain was left in the field, the decline concave adjustments, or from both. High loss of in head rice yield from the maximum was 1.4 threshed seed came from poor separation in the percent for Caloro, 0.9 percent for Calrose, and straw walkers and cleaning shoe. They found 1.0 percent for Colusa. that under California conditions reel shattering Most ricegrowers determine the moisture con- losses normally were insignificant in rice as com- tent of hand-harvested samples of their rice be- pared with other small grains. fore beginning harvest. Determinations usually Curley and Goss suggest that several loss checks are made with electrically operated moisture should be made on a machine in a given area to meters, which they own or which are available at determine the effect of adjustment or change in the commercial driers. ground speed. Detailed recommendations for ma- Although kernel moisture content at harvest- chine and procedural adjustments for harvesting time strongly influences rice quality and milling rice under California conditions also are listed by characters, environmental factors that affect the these workers. plant physiologically during the growing season MOISTURE CONTENT OF GRAIN AT HARVEST.— also influence quality. Halick {Jf8) has shown Smith and others {127) pointed out that rice must that a variety that ripened under lower tempera- be of high milling quality to command a premium tures (81° to 84° F.) produced higher head rice price, and that for this high quality and for milling yields than did rice that ripened earlier maximum grain yields, rice must be cut at the in the season under higher temperatures (90° to proper stage of maturity. If the crop is har- 94°). Stansel, Halick, and Rramer {m)io\mà. vested when immature, field yields usually are that high temperatures (90° day and 80° night) reduced and the breakage in combining and mil- increased chalkiness in all four varieties studied ling is excessive because of the light, chalky ker- (Century Patna 231, Bluebonnet 50, Toro, and nels. If the crop is left in the field until" over- a glutinous variety). California rice quality RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 103 studies (73) showed that certain crop fertilization ing the rice if the moisture content was reduced practices could result in declines in kernel char- only about 2 percent at each drying operation and acters such as weight, water uptake, hot-paste the rice was allowed to remain in storage 12 to 24 viscosity, and whiteness. Thus, when harvesting hours between drying periods. However, when for maximum quality, many factors must be con- necessary to dry a given lot of rice in one opera- sidered; but certainly moisture content of grain tion, the drying-air temperature should not exceed at harvesttime is among the most important. 110°. PREHARVEST CHEMICAL DRYING.—Results from From experiments conducted with combined experiments with the preharvest application of rice in 1944, 1945, and 1946, McNeal (78) con- chemical desiccants to speed the drying of rice in cluded that in most cases the head rice yield was the field have been reported by Addicott and increased and the total drying time was decreased Lynch (9), Hinkle (57, 58, 59), Smith, Hinkle, as the number of dryings was increased from one a¿d Williams (123), Tullis (139), and Williams to four at temperatures ranging from 100° to {U7). All materials were applied as sprays when 150° F.; and the tempering period between dry- the rice contained from 20 to 27 percent mois- ings was important, since it gave the moisture m ture. Materials tested at varying concentrations the grain an opportunity to equalize and thereby included (1) sodium chlorate-borate mixtures; reduced drying time. On the basis of more recent (2) magnesium chlorate; (3) disodium 3,6- experiments, McNeal (81) concluded that the endoxohexahydrophthalate (alone and with am- most desirable drying combination appeared to be monium sulfate) ; (4) sodium monochloroacetate ; four dryings at 120°. (5) S, S, S,-tributyl phosphorotrithioate; (6) In 1953, Aldred (10) summarized research on sodium pentachlorophenate; (7) di-nitro-O-sec- drying and storing rough rice in the Southern butylphenal compounds (alone and in combina- States. This summary covered work conducted tion with aromatic oils) ; and (8) aromatic oils by the Agricultural Experiment Stations in alone. Some of the chemicals studied by these Arkansas, Louisiana, and Texas, and by the U.S. investigators hastened the drying of rice in the Department of Agriculture. This author gives field. However, none were entirely satisfactory information on volume of air used in column- because the milling quality was reduced, the ker- type and bin-type driers; number of stages to nels were discolored, or the chemical imparted an use in drying rice; temperature of the air for off-flavor to the rice. drying; depth of rice when dried in bins; length Desiccants are used occasionally to hasten the of time rice can be held before drying; and the drying of seed rice. However, no grower should use of fumigants to protect rice from storage use a desiccating chemical on his maturing rice insects. crop until he has checked with his local agricul- A comprehensive review of research in the tural authorities to determine its legal status with United States on conditioning and storing rough reference to chemical residue tolerances. Laws and milled rice through 1958 (23) was published are strictly enforced in this regard, and an entire in 1959. This reidew cited 74 specific references crop could be impounded if it exceeds the legally and included participation by 36 contributors. established chemical residue tolerances. TYPES OF DRIERS.—Driers can be classified by type as (1) continuous flow, including mixing and Drying and Storing nonmixing; and (2) batch, including bins and For the proper drying of rice, moisture must be- potholes. Driers can also be classified as multi- removed from inside the kernel (23). If rice is pass and uni-pass. Multi-pass is a continuous- dried too rapidly or if the temperature of the flow system; uni-pass is a batch system. drying air is too high, quality is seriously im- Wasserman and others (1^2) reported that paired. To prevent internal checking or breaking mixing-type driers are of many designs. Two of of the kernels from drying too rapidly, drying the most popular mixing-type driers are the baffle usually is done in three to five stages. In each design and the Louisiana State University (LSU) stage the rice passes through the drier and then design (1), In the baffle design, rice is conducted is tempered in a bin, so that the kernel moisture downward in a zigzag path by means of baffles, will equilibrate. while heated air is forced through the grain. In Bainer (13) published one of the earliest ac- the LSU design of the baffle drier, layers of counts of artificial drying of combine-harvested inverted-V-shaped air channels are installed in rice. He concluded that rice could be dried suc- a bin with alternating air-inlet and air-exhaust cessfully by artificial means but that the tem- channels. Each layer is offset, so that the tops of peratures in the drier should not exceed 100° F. the inverted Vs split the streams of grain as it Smith and others (126) reported on early re- flows down between the channels. Drying air search on artificial drying of rice in Arkansas and passes from the air-inlet channels through the rice Texas. They concluded that a drying-air tem- and out the air-exhaust channels (142). perature of 120° F. could be used without injur- Wasserman and others {H2) stated that the AORÏCULTURE líANDBOOK 2 8 9, U.S, DEFT, OF AGRICULTURE 104 SOURCES OF HEAT FOR DRIERS.—The amount of nonmixing columnar type drier is the simplest heat required for warming the air used by a rice and most commonly used. In this drier, rice drier depends on the initial temperature and mois- descends between two parallel screens set 4 to 6 ture content of the air. The approximate quan- inches apart while heated air is blown through the screens and intervening rice. No appreciable tity of lieat required to raise the temperature of mixing occurs, and the effect is similar to drying each 1,000 cubic feet of air and its moisture 1° F. in a static bed with a depth equal to the distance is about 18.1 B.t.u.'s. To take care of initial air temperature, heat losses, and periods of above between the screens. According to Morrison, Davis, and borenson average humidity, results of experiments at ( grain until it can be moved through the drier, (2) mation about the use of these diemicals, contact to remove harvest or drier heat, (3) to remove your local agricultural authorities. small amounts of moisture (1 to 2 percent), and Stored rice is subject to attack by a number of (4) to maintain the quality of grain during stor- insects. The lesser grain borer {Rhyzopertha age. Aeration is defined as the moving of air dommwa (F.)), the Angoumois grain moth through stored grain at low airflow rates (gen- {Sitotro^a cerealeUa (Oliv.) ), and the rice Aveevil erally between one-tenth and one-fifth cubic feet {SitophiJ'us oryzcie (L.) ) attack sound rough rice per minute per 100 pounds) for purposes other kernels. The cadelle {Tenehroides mauritanicus than drying, to maintain or improve its value. (L.) ), the saw-toothed grain beetle {Oryzat ^hilus Several types of aeration systems are described, sni'inameiisis (L.) ), the flat grain beetle {Crypto- as-are methods of operation and controls. lestes piis'dJus (Schon.) ), the red flour beetle (T'n- Aldred {10) presented the following conclu- hoUum castaneum (Herbst)), and the confused sions regarding storage and aeration of rice : flour beetle {T, confusiwi (Duv.)) attack broken (1) Based on information to date (1952), rice or dehulled kernels. Moths that infest the sur- in bulk storage should be turned once every 2 face of Ijulk or bagged rough rice and spin web- months during the winter and at least once a bing in profusion include the Indian-meal moth month during the summer. {PJocUa interpuncteIJa (Hbn.) ), the almond moth {E'phestia cauteUa (Wlkr.)), and the rice moth (2) With proper aeration, rice with a moisture {Coreyra eephalonka (Staint.) ). In storing bran content of IS to 24 percent can be kept for a and milled rice, control of the bran bugs, includ- week or 10 days without spoilage. ing the flour beetles, is important {108, 11¡.0), (3) For retaining rice with a moisture content of 18 to 24 percent before drying, 2 cubic feet Selected References per minute per 100 pounds is adequate. After the rice has been parth^ dried, one-half cubic foot (1) ANONYMOUS. 1947. RICE DKYING AND STOKAGE IN LOUISIANA. LIL per minute per 100 pounds is adequate. Agr. Expt. Sta. Bui. 416, 22 pp. (4) Eice with a moisture content below 16 per- (2) cent can be kept several months in either cool or 1949. STOP—DON'T PLANT RED RICE Rice Jour. 52(li) : 20. warm weather with the aid of aeration. (3) As pointed out by Dachtler (¿-i), practically 196: UNDERGROUND IRRIGATION. Rice Jour. 65(9) all rough rice is stored in bulk, although sack 22, 23, ilUis. (41 AD AIR, C.I R. storage is practical for relatively small lots and 1940 EFFECT OF TIME OF SEEDING ON YIELD, MILL- for seed rice. A maximum moisture content of ING QI-^ALITY, AND OTHER CHARACTERS IN 12 percent is recommended for seed rice, but up to RICE. Auier. Soe. Agron. Jour. 32: 697-70(1 14 percent usually is safe in bulk storage. The ( o ) and CRALLEY, E. M. length of the storage period for rice depends on 1950. 1949 RICE YIELD AND DISEASE CONTROL TESTS. Ark. Agr. Expt. Sta. Rpt. Ser. 15, 20 pp. market conditions, but it usually is from 5 to 8 (6) and ENGLER, KYLE. months. For any common-type storage bin, any 195; THE IRRKiATlON AND CULTURE OF RICE. hi type of construction material is satisfactory if it Water, U.S. Dept. Agr. Yearl)onk of Agr., results in a storage structure that will keep the pp. 389-894. (7) BEACHELL, H. .AI., JODON, N. E., and others. grain dry, cool, and free of insects and other pests 1942. COMPARATIVE YIELDS OF TRANSPLANTED AND and if it provides job safety and convenience DH^ECT SOWN RICE. Auicr. Soc. AgroD. Jour. while moving and inspecting the grain. Dachtler 34: 129-187. warned that if dried rough rice is to be stored for (8) :MTLLER, :M. I)., and BEA( HELL, H. M. 1962 RICE IMPROVEMENT AND CULTURE IX THE a few months or longer or if damp rice is to be uxriED STATES. Adv. in Agron. 14: 61-108, held before drying, the storage structure should illus. be equipped for aeration. (9) ADDK'OTT, F. T., and LYNCH, R. S. IxsECT INFESTATION OF STORED RICE.—Insect 1957. DEFOLIATION AND DESICCATION : HARVEST-AID PRACTICES. Adv. in Agron. 9: 67-93. infestation generally occurs after rice is in stor- (10) ALDRED, F. L. (editor). age, since most rice han^ested and dried by mod- 19o8. RECENT RESEARCH ON DRYING AND STORAGE OF ern methods is relatively free of insects upon en- ROUGH RICE. South. Coop. Ser. Bul. 29, 29 tering storage (23), Insect control practices that pp., illus. (11 ) ANDERSON. K. L., and MCKIE, J. W. are used before and during storage have been 196-!. GROWING RICE IN THE MISSISSIPPI DELTA. developed through research and are widely ap- Miss. Agi-. Ext. Serv. Pub. 219. plied. Emphasis now is being placed on the use (12) ATKINS, J. G., CRALLEY, E. M., and CHILTON, S. J. P. of protective treatment. Chemicals are now 195 UNIFORM RICE SEED TREATMENT TESTS IN ARKANSAS, LOlîISIANA, AND TEXAS, 1955-5(j. available that can be mixed with or sprayed on Plant Dis. Rptr. 41: 105-108. the rice as it is stored and that will protect it (13) BAINER, R. against invading insects yet leave no residues 1932. HARVESTING AND DRYING ROUGH RICE IN CALI- harmful to human beings {108, 11^0), For infor- FORNIA. Univ. of Calif., Div. of Agr. Sei. Bul. 541, 29 pp., illus. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 107 BAMESBERGER, J. G. (14) (32) and BEACHELL, H. M. 1954. LAND LEVELING FOR IRRIGATION. U.S. Dept. 1962. SECOND-CROP RICE PRODUCTION IN TEXAS. TeX Agr. Leaflet 371, 8 pp., illus. Agr. Prog. 8(6) : 25-28. (15) BAER, H. T., WRATTEN, F. T., POOLE, W. D., and (33) and WEIHING, R. M. WALKER, R. P. 195 FERTILIZER REQUIREMENTS FOR RICE IN RICE- 1955. RECOMMENDATIONS FOR BIN DRYING AND PASTURE ROTATIONS. Tex. Agr. Expt. Sta STORAGE Of ROUGH RICE IN LOUISIANA. ReV., Prog. Rpt. 1948, 4 pp. La. Agr. Expt. Sta., Agr. Engin. Dept. Cir. (34) FAULKNER, M. D. 18,16 pp. [Processed.] 1960. WATER PLANTING STUDIES. Kice Jour (16) BLACK, D. E., and WALKER, R. K. 63(7) : 4^50. 1955. THE VALUE OF PASTURES IN ROTATION WITH (35) and MiEARs, R. J. RICE. La. Agi'. Expt. sta. Bui. 498, 24 pp., 1962. LE\^ELING RICE LAND IN WATER. La. Agr. illus. 5(4) : 3, 16, illus. (17) CALDERWOOD, D. L., and HUTCHINSON, R. S. (36) FiNFROCK, D. C, and MILLER, M. D. 1961. DRYING RICE IN HEATED AIR DRYERS WITH AERATION AS A SUPPLEMENT TREATMENT. 1958. ESTABLISHING A RICE STAND. Univ. of Calif. U.S. Agr. Market. Res. Rpt. 508, 22 pp. Div. Of Agr. Sei. Leaflet 99, 12 pp., illus. (37) (18) CHAMBLISS, C. E. RANEY, F. M., MILLER, M. D., and BOOHER, 1920. PRAIRIE RICE CULTURE IN THE UNITED STATES. L. J. U.S. Dept. Agr. Farmers' Bui. 1092, 26" pp., 1960. WATER ^[ANAGEMENT IN RICE PRODUCTION. illus. Univ. Of Calif. Div. of Agr. Sei. Leaflet 131, (19) and JENKINS, J. M. 2 pp., illus. 1925. EXPERIMENTS IN RICE PRODUCTION IN SOUTH- (38) VISTE, K. L., HARVEY, W. A., and MILLER, WESTERN LOUISIANA. U.S. Dept. Agr. Dept. M. D. Bui. 1356, 32 pp., illus. 1957. WEED CONTROL IN RICE Univ. Of Calif. Div. (20) CHAPMAN, A. L., and PETERSON, M. L. of Agr. Sei. Leaflet 97 2 pp., illus. 1962. THE SEEDLING ESTABLISHMENT OF RICE UNDER (39) GARRISON, R. H. WATER IN RELATION TO TEMPERATURE AND 1959. GOOD SEED DOES NOT COST, IT PAYS HANDSOME DISSOLVED OXYGEN. Crop Sci. 2(5) : 391- DIVIDENDS. Seedmen's Digest, Aug., pp. 22, 395. 23, 44, illus. (21) CLARK, F.. XEARPASS, D. C, and SPECHT, A. W. "^(40) GATTIS, J. L., KOCH, K. A., and MCVEY, J. L. 1957. INFLUENCE OF ORGANIC ADDITIONS AND FLOOD- 1959. LAND GRADING FOR SURFACE IRRIGATION. Ark. ING ON IRON AND MANGANESE UPTAKE BY RICE. Agr. Ext. Serv. Cir. 491, 29 pp., illus. Agron. Jour. 49 : 586-589. (41) GAY, B. (22) CuRLEY, R. G., and Goss, J. R. 1961. 'RATOUNING' METHODS OF A TEXAS RICE 1964. ESTIMATING COMBINE LOSSES IN RICE. UuiV. FARMER. Rice Jour. 64(2) : 22. Calif., Dept. Agr. Engin., 4 pp. [Unnum- (42) GERLOW, A., and MULI.INS, T. bered. Mimeographed.] 1958. RESERVOIRS FUR IRRIGATION IN THE GRAND (23) DACHTLER, W. C. (editor). PRAIRIE AREA : Ax\ ECONOMIC APPRAISAL 1959. RESEARCH ON CONDITIONING AND STORAGE OF Ark. Agr. Expt. Sta. Bui. 606, 24 pp, ROUGH AND MILLED RI( E A REVIEW THROUGH (43) Goss, W. L., and BROWN, E. 1958. U.S. Agr. Res. Serv. ARS 20-7, 55 pp.. 1939. BURIED RED RICE SEED, Agron. Jour. 31: 633- illus. 637. (24) DAVIS, J. H., SONNIER, E. A., and WHITE, T. W. (44) GRAY, L. C. and THOMPSON, E. K. 1963. PASTURE-RICE ROTATIONS FOR SOUTHWEST 1041. HISTORY UF AGRICULTURE IN THE SOUTHERN LOUISIANA. La. Agr. 7(1) : 4-5. u. s. TO 1860. Carnegie Inst. Wash. Pub. (25) DAVIS, L. L. 430. Peter Smith, New York. [Reprinted 1944. HARVESTING RICE FOR MAXIMUM MILLING in 2 vols.] QUALITY IN CALIFORNIA. Rice Jour. 47(3) : (45) GREEN. B. L. 3-4,17-18, illus. 1961. FISH FARMING ; PAST, PRESENT, FUTURE. Ark (26) Agr. Ecun.3(4) : 1,2. 1950. CALIFORNIA RICE PRODUCTION. Calif. AgT. (46) and ]\IULLINS, T. Ext. Serv. Cir. 163, 55 pp., illus. 1959. USE OF RESERVOIRS FOR PRODUCTION OF FISH (27) DOCKINS, J. O. IN THE RICE AREAS OF ARKANSAS. Ark. Agr. 1950. PRODUCING QUALITY SEED RICE DEEMED VITAL Expt. Sta. Spec. Rpt. 9, 16 pp. TO ARKANSAS RICE INDUSTRY. Rice JOUT. (47) and WHITE, J. H. 53(5) : 21, 35. 1963. COMPARISON OF THREE SELECTED ROTATIONS (28) EHRLER, W., and BERNSTEIN, L. IN EASTERN ARKANSAS. Ark. Agr. Expt. 1958. EFFECTS OF ROOT TEMPERATURE, MINERAL NU- Sta. Bui. 664, 20 pp., illus. TRITION, AND SALINITY ON THE GROWTH AND (48) HALICK, J. V. COMPOSITION OF RICE. Bot. Gaz. 120(2) : 1960. EFFECT OF TEMPERATURE DURING RIPENING ON 67-74. QUALITY CHARACTERISTICS OF RICE. Rice (29) ENGLER, KYLE. Tech. Working Group Proc, June 29 to 1958. WATER LEVELS IN RICE IRRIGATION WELLS IN July 1, Lafayette, La. MP 488, p. 14. THE GRAND PRAIRIE REGION. Ark. Farm Res. (49) HALL, H. Y. 7(3) : 12. 1959. GREENHOUSE STUDIES ON THE RELATION OF (30) THOMPSON, D. G., and KAZMANN, R. G. WATER MANAGEMENT TO THE GROWTH OF RICE. 1945. GROUND WATER SUPPLIES FOR RICE IRRIGATION Ark. Agr. Expt. Sta. Rpt. Ser. 89, 22 pp. IN THE GRAND PRAIRIE REGION. ARKANSAS. ( 50 ) Ark. Agr. Expt. Sta. Bui. 457, 56 pp., illus. 1960. WATER SEEDING OF RICE IN ARKANSAS. Rice (31) EVATT, N. S. Jour. 63(13) : 13. 1958. FERTILIZER-WATER DEPTHS TESTS ON RICE, (51) and THOMPSON, L. F. 1956-57. Tex. Agr. Expt. Sta. Prog. Rpt. 1962. SALINITY AND ALKALINITY OF RICE SOILS IN 2006, 4 pp. ARKANSAS. Ark. Farm Res. 11(2) : 11. 108 AûKiGULTiMivE HANDBOOK 289. U.S. DEPT. OF AGRICULTURE (52 HASKICLL, C. G. (72 ) KESTEE, E. B. 1915. IRRIGATION PRACTICE TX IMCK GROWINC, U.S. 1959. EFFECTS OF CERTAIN PREPROCESSING AND CUL- r)ept. Ai::r. Fanners' l;uî. CtTS, 12 pp. TURAL VARIABLES UPON MILLING AND OTHER (53) HENDERSON, S. M. PROCESSING QUALITIES OF RICE. Calif. Rice 19i )-t. THE CAUSES AND ( IiARA( TERISTICS UE KICE Res. S^^mp. Proc, Albany, Calif., pp. 6-12 CHECKING. lUce J(nir. 57(5) : 16, 18. (73) and PENCE, J. W. (54) 1962. RICE INVESTIGATIONS AT WESTERN REGIONAL 1955, DEEP-BED KICE DRIER PEKIOKMANCE. Agr. Eii- RESEARCH LABORATORY^ Rlce JOUP. 65(7) ' gill. 3G : 817-820. 45-47, illus. (55) (74) KING, B. M. 1958 DEEP-BED GRAIN DRYINCi ON THE RANCH WITH 1937. THE UTLLIZATI0N OF WABASK CLAY' ( GUMBO j UNHEATED AIR. Uiiiv. of Calif. Div. of Agr. SOILS IN CR(JP PRODUCTION. ^Nio. Agí Expt Sei. Leaflet 103. 2 pp. Sta. Bui. 254, pp. 12-32. (5G) HiLDRETH. I\. J.. and SORENSON, J. W., JE. í75> LEWIS, D. C, SCOTT. V. H., MUTELLER, K. E., and 1957. PROFITS AND LOSS FROM ON-EAR.M DRYING AND others. STORAGE OF RICE IN TEXAS. TOX. A2:r. Expt. 1962. NEW RICE LEVEE CONCEPTS. Rice Jour 65(4) • Sta.Biil.86o, IGpp. 6-15. (57) HiNKLE, I). A. (76) MCFARLANE V. H., HOGAN, J. T., and MCLEMORE 1952. FIELD DRYING OF RICE P.Y CHEMICALS. South. T. A. Weed Conf. Proc. 5 : 11 5-177. 1955. EFFECTS OF HEAT TREATMENT ON THE VIA- (58) BILITY OF RICE. U.S. Dept. Agr. Tech. Bui 1953. EFFECT OF PRE-HARVEST CHEMICALS LPON 1129, 51 pp., illus COMBINE EFFICIENCY.' AND MILLING YIELD OF (77» MACKIE, W. W. RICE. South. Weed Coiif. Proc. 0: 72-75. 1943. RICE IN THE IMPERIAL VALi^EY (CALIFORNIA). (59) Imp. Rice Growers' Coop. Assoc. [Un- 1954. PRE-HAR\'EST TREATMENT OF RICE AS AN AID numbered Rpt. ] IN DRYING. Rice Tech. Working Oroup (78} MCNEAX, 'XZIN. Proc. 6 • 1(>-17. 1949. ARTIFICIAL DRYING OF COMBINED RICE. Ark. (60) HuTCHiNsoN, R. S., and WILLMS, E. F. Agr. Expt Sta. Bul. 487, 30 pp 1962. OPERATING GRAIN AERATION SYSTEZ^IS IN THE (TS) SOUTHWEST. U.S. Dept. Agr. Market Re? 195Ö. EFFECT OF COMBINE ADJUSTMENT ON HAR- Rpt. 512, 20 pp., illus. VEST LOSSES OF RICE. ArK. Agr. Expt. Sta (61) HURST, W. :\L, and HUMPHRIES, W. R. Bui. 500, 26 pp., illus 1955. HAEVESTINC WITH COMBINES. I\S. Dept. (80^ Agr. Farmers' Bui. 1761, 40 pp., illus. 1950. WHEN TO HARVEST RICE FOR BEST MILLING (62) JENKINS, J. :\i., and JONES, J. W. QUALITY AND GERMINATION. Ark. Agr 1944. RESULTS OF EXPERIMENTS WITH RICE IN LoLM- Expt. Sta. Bui. 504, 41 pp siANA. La. Agr. Expt. Sta. Bui. 384, 30 pp. (81) (63) JoDON, N. E. 1961. EFFECTS OF DRYING TECHNIQUES AND TEM- 1953. GROWING PERIOD OF LEADING RICE VARIETIE.s PERATURES ON HEAD RICE YIELDS. Ark. WHEN SOWN ON DIFFERENT DATES. La. Agr Expt. Sta. Bui. 476, 8 pp. Agr. Expt. Sta. Bui. 640, 22 pp., illus. (82) MARR, J. C. (64) JOHNSTON, T. H., ADAIE, C. li. TEMPLETON,ON, G. E.. and others. 1957. GRADING LAND FOR SURFACE IRRIGATION. Univ. of Calif. Div. Agr. Sei. Cir. 438, 48 1963. NOVA AND VEGOLD NEW RICE VARIETIES. pp., illus. Ark. Agr. Expt. Sta. Bui. 675, 24 pp., illus. (83) MiKKELSEN, D. S., FiNFROCK, D. C, and MILLER, (65) and CRALLEY. E. M. M. D. 1955. RICE VARIETIES AND THEIR YIELDS IN ARKAN- 1958. RICE FERTILIZATION. Calif. Agr. Expt. sta. SAS, 1948-1954. Ark. Agr Expt. Sta. Rpt. Ser. 49, 20 pp. Ext. Serv. Leaflet 96, 12 pp., illus. (84) and SINAH, M. N. (6^J) —^r~ ^-^-^i^i^EY, E. M., and HENRY^ S. E. 1959. PERFORMANCE OF RICE VARIETIES IN ARKAN- 1961. GERMINATION INHIBITION IN ORYZA 8ATIVA SAS, 1953-1958. Ark. Agr. Expt Sta. Rpt. AND CONTROL BY PREPLANTINQ SOAKING Ser. 85, 31pp., illus, TREATMENTS. Crop Sci. 1 I 332-335. (85) MORRISON, S. R. (67) JONES, J. W., ADAIR, C. R., JODON, N. E., and oth ers. 1953. RICE IRRIGATION TESTS AT THE BEAUMONT 1947 EFFECT OF ENVIRONMENT AND SOX'RCE OF SEED ON YIELD AND OTHER CHARACTERS IN RICE. STATION, 1952. Tex. Agr. Expt. Sta. Prog. Rpt. 1542, 2 pp. Amer. Soc. Agron. Jour. 39: 874-886. (86) ——— DAVIS, W. C, and SORENSON, J. W., JE. (68) DAVIS, L. L., and WLLLIAMS, A. H. 19o4. BIN DRYING OF RICE AT THE RICE-PASTURE 1950. RICE CULTURE IN ( ALIFORNIA. U.S. Dept. Agr. Farmers' Bui. 2022, 32 pp., ilUis. EXPERIMENT STATION, 1953-54. Tex. Agr. (69) DocKiNs, J. ()., WALKER, R. K., and 1 )AVL^ .o^v .. ^^^- ^^^' P^^^ I^Pt- Iß'^O, 9 pp. W. C. (87) MucKEL, D. C. 1959. REPLENISHING UNDERGROUND WATER SUP- 1952. RICE PRODUCTION IN THE SOUTHERN STATES. U.S. Dept. Agr. Farmers' Bui. 2043, 36 pp., PLIES ON THE FARM. U.S. Dept. Agr. Leaflet illus 452,8 pp., illus. (70) (88) MuLLiNs, T. JENKINS J. M., W^YCHE, R. LI., and NELS( )N, 1954. ECONOMIC APPRAISAL OF FARMING PRACTICES RICE CULTURE IN THE UNITED STATES. AND ROTATION PROGRAMS ON LOUISIANA RICE U.S. Dept. Agr. Farmers' Bul. 1808, 29 pp.. FARMS. La. Agr. Expt Sta. Bui. 491, 40 illus. pp. (Tl) KAPP, L. (\ (89) 1947. 1960. PRODUCTION PRACTICES, COSTS AND RETURNS THE EFFECT OF COMMON SALT ON RICE PRO FOR MAJOR ENTERPRISES ON RICE FARMS IN DucTioN. Ark. Agr. Expt. Sta. Bui. 465, 7 pp. THE DELTA AREA OF MISSISSIPPI. MÍSS. Agr. Expt. Sta. Bui. 595, 24 pp. RICE IN THE UNITED STATES : VAPJETIES AND PRODUCTION 109 (90) MiTLTJNS, T., and SLUSHER, M. W. (110) 1950. COMPAEISON OF FARMING SYSTEMS FOR SMALL 1961. INFRA-RED DRYING v>F ROUGH RICE Hi RICE FAJRMS IN ARKANSAS. Ark. Agi*. Expt. MEDIUM-GRAIN TYPE NATu AND .MACNOLIA Sta. B-ul. 498, 44 pp., illus. Rice Jour. 64(1): 11^12. 24-27, illu^ (91) and SLUSHER, M. W. (Ill) and RosBER(3, D. W. 1951. COMPARISON OF FARMING SYSTEMS FOR LARGE 1959. DRYING ROUGH RÎCÊ WITH INFKA-RED RADIA RICE FAEMS IN ARKANSAS. Ark. AgT. Expt. TION. Tex. Agr. Expt. Sta. MP-354 (May; Sta. Bui. 509, 40 pp. 4 pp. (92) NELSON, G. S. (112) and RosBERG, D. W 1961. AERIAL APPLICATIONS OF GRANI'LAR AND PEL- U)(>0 INFRA-REI» DRYINO ()K lí^UGIÍ KH'K, 1. T NC- LETED MATERIALS AND SEEDS. RICE JOUT. GRAIN TYPE RFXORr. AND BLUEBONNE^^: 5(\ 64(7) : 26-27. Rice Jour. 63(12): 3-5. 28-27, illus, (93) NELSON, M. (113) SCOTT. V. H., LEWIS, D, C... Fox, I>, R., and BABE, 1931. PRELIMINARY REPORT ON CULTURAL AND FEK A, F. TILIZER EXPERIMENTS WITH RICE IN ARKAI^- 1961. PLASTIC LEVEES FOR ?JCE IRRIGATION. Calif SAS. Ark. Agr. Expt. Sta. Bui. 264, 46 pp Agr. 15(11) : 8, 9. (94) Q14) SENEWIRATNE, S. T., and MIKKELSEN, D S. 1944. ROTATION, CPILTUBAL AND IRRIGATION PRAC- 1961, PHYSIOLOGICAL FA^;TORS LIMITING GROWTH TICES AFFECTING RICE PRODPCTION. Ark. AND YIELDS OF ORYZA SATIVA UNDER UN- Agr. Expt. Sua. Bul. 445, 45 pi. FLOODED CONDITIONS. Plant and Soil 14 : (95) OvERSTREET, R., and SCHL-UZ, R. PI. 127-14G. 195S. THE EFFECT OF RICE CLOTURE ON A NON- (115) SIMMONS,, C. F. SALINE SODIC SOIL OF THE FRESNO SERIES. 1940. RICE PRODUCTION AND RICELAND USES IN AR- Hilgardia 27(12); 319-332, illus KANSAS, Ark. Agr. Ext Serv. Cir. 424, (96) PEARSON, G. .-:... 16 pp 1959. FACTORS INFLUENCING SALINITY OF SUB- (116) SIMS, J, L. MERGED SOILS AND GROWTH OF CALORO RICE. 1961. FISH-RICE PROJECT PLAN^ El Jour. SoilSci. 8T(4) : 19&-206. o4í7) • 2: (97 (117> 1961. THE SALT TOLERANCE OF RICE, Internat!. 196-i. NITROGEN AVAILABILITY IN RICE FIELD AN7 Rice Comn. Newsletter 10(1) : 1^. RESERVOIR SOILS. A]'k F'ATiu Res. 13(2' (98) and AYERS, A. D. (118) 1960. RICE AS A CROP FOR SALT-AFFECTED SOIL IN 1964. GROWTH OF ARABLE CROPS AS A I^fEANS OF PROCESS OF RECLAMATION. U.S. Dept. A.gr. DE nCING AVAILABLE NITROGEN IN RESERVOIR Prod. Res. Rpt, 43, 13 pp., illus. SOU., Ark. Farm Ros, 18(3). (99) and BERNSTEIN, L. (119) SLUSHE-:, I\: W. 1959 SALINITY EFFECTS AT SEVERAL GROWTH 1953 THE USF. ot AIRPLANES ON RICE FAEMS IN STAGES OF RICL. Agr OU, Jour. 51 : 654-657, ARKANSAS, ArK. Agr, Ex[,;.. Sra. Bui, 541, (100) PERKINS, W. R., and LUND, C, F. 1950. CROP ROTATION ON EICF FAr^MS. Alk. A^T. (120) Ext. Serv. Leaf et 1Z4 1955. ENTERPRISE roSTS AND RETURNS ON RICE (101) PoMiNSKi, J.. WASSERMAN T., SPADARU J. J., and FARMS. .Ark. Agr, Expt. Sta. Bui. 549,, 34 others. pp., illui. 1961. IMPEO^^EMENTS IN COMMERCIAL DRYING OF (121) and Miu-LJNS, T SOUTHERN GROWN RICE. I. ZENITH—A 194S. MECHANIZATION OF THE RICE HARVEST, Ark. MEDIUM-GRAIN VARIETY. Rice JOUT, 64(9' : Agr. Expt Sta. Rut. Ser. 11, 32 pp ^ illus 10, 12-13, 16-17. (122) and ^TTTTXINS, T. (102) RANT:Y, F. C. 1952. RICE MILL YIELD ^NL GRADE IN RELATION TO 1959. WARMING BASINS AND WATER TEMPERATURE. VARIETi AND METFloD OI HARVEST Ark, Calif. Ri':e E^-L 2p. Prn Albanv, Tal f. Agr. Expt Sta. Bui. 526, 36 pp^ ilius. pp. 20-23. , (123) SMITH, R'. J, JR., HINKLE.. D. A., and WILLIAMS, (103) HAGAN. R. ^1.., and FINFROCK, D. L. F J 1957 WATER TEMPERATURE IN IRRIGATION. Calif. 1059. PRE-H^R\"EST DESICCATION OF RICE WITH Agr. 11(4) ; 19, 20, 37. illus. CHEMICAL,^. Ark. ^gr. Expt. Sta. Bui. 61Ê. (104) REED, J. F., and STURGIS, M. B. 16 pp., illus. 1936. TOXICITT FROM ARSENIC COMPOUNDS TU KI-:E (124) SMITH, W. D. ON FLOODED soHS. Amer. Soc. Agron. JOLT 1940. HANDLING ROIIGH RICE TO PRODUCE HIGH 28: 432-436. GRADES, U.S. Dept. Agr. Farmers' Bui. (105) REYNOLDS, E. B. 1420, 21 pp., -Uus 1954. RESEARCH ON RICE PRODUCTION IN TEXAí- (125) L>EFFEs J. J.„ BENNETT, C. H., and HURST, Tex. Agr. Expt. Sta. Bui. 775, 29 pp., lllu^^. W. M (106) ROBERTSON, R. D. 1930 DRYUTG .'jOIvíBINE ITAR^-^ESTED RICE ON THE 1917. IRRIGATION OF RICE IN CALIFORNIA. Calif. FARM. U.S. Dept. Agr., U.S. Grain Stand- Agr. Expt. Sta- Bui. 279, pp. 253-270, illus. ards Act-Graui Investigacions 57, 20 pp. (107) ROLSTON, L. H., and ROUSE, PHLL. Q26) DEFFES,. J. J., BENNETT, G. H., and others, 1960. CONTROL OF GRAPE COLASPIS AND RICE WATER 1933 ARTIFICIAL DRYING OF RICE ON THE FARM. WEEVIL BY SEED OR SOIL TREATMENT. Ark. U.S. Dept. Agr, Gir, 292, 24 pp., illus. Agr. Expt. Sta. Buh 624, 10 pp. (^27) DEFFES, J J., BENNETT, G. Tí. and others. (108) ROUSE, PHIL, ROLSTON, L. H., and LINCOLN, r 1938. EFFECT OF DATE OF HAR\^ST ON YIELD AND 1958. INSECTS ... IN FARM-STORED RICE. Ark MILLING QUALITY OF RICE. U.S. Dept. AgT. Agr. Expt, Sta. Bui. 600, 25 pp. Gir. 484. 20 pp. (109) SCHROEDEB, H. W. 1960. INFEA-EED DRYING OF ROUGH RICE. II. (128) SONNIER, A. I960 CATFISH, CRAYFISH AND RICE. Rlce JOUF, SHORT GRAIN TYPE CALEOSE AND CALORO. Rice Jour, 63(13) : 6-8, 25-28. 63(5) : 6, S„ 9, illus. no AHÍilCi'i/ïiUiK ^lANDBOOK 2 8 9, IT.8. DEPT. OF AGRICULTURE (139) SoRENsoN, J. W., JR. (141) WALKER, R. K., and STURGIS, M. B. 1957. SUPPLEMENTAL HEAT KOK DRYING RICE IN 1946. A TWELVE-MONTH GRAZING PROGRAM FOR THE FARM STORAGE BINS. TeX. AgV. Expt. StU., RICE AREA OF LOUISIANA. La. Agr. Expt Dept. AgV. Engin., 9 pp. [Proressed Rpt.] Sta. Bui. 407, 19 pp. (130) (142) WASSERMAN, T., FERREL, R. E., BROWN, A. H., and 1958. RECOMMENDATIONS FOR DRYING AND STORING SMITH, G. S. RICE IN FARM STORAGE BINS. TeX. Agi*. 1957. COMMERCIAL DRYING OF WESTERN RICE. CE- Expt. Sta., Dept. Agr. Engin. [Processed real Chem. Today 2(9) : 251-254. Rpt] (143) FERREL, R. E,, KAUFMAN, V. F., and others. (131) and DAVIS, W. C. 1958. IMPROVEMENTS IN COMMERCIAL DRYING OF 1955. DRYING AND STORING ROUGH RICE IN FARM WESTERN RICE. I. MIXING TYPE DRYER STORAGE BINS, 1954-55. Tex. Agr. Expt. Sta. LOI^ISIANA STATE UNIVERSITY DESIGN. Rice Prog. Rpt. 1819, 8 pp. Jour. 61(4) : 30-32, 34-36, 38; 61(5) : 40 (132) DAVIS, W. C, and HOLLINGSWORTH, J. P. 42-46. 1948. DRYING RICE IN SACKS. Tex. Agr. Expt. (144) FERREL, R. E., KAUFMAN, V. F., and others. Sta. Prog. Rpt. 1138, 4 pp. 1958. IMPROVEMENTS IN COMMERCIAL DRYING OF (133) SPADARO, J. J. W^ESTERN RICE. II. NON-MIXING COLUMNAR- 1961. EVALUATION OF WRRL DRYING METHODS ON TYPE DRYER. Rice Jour. 61(7) : 9-12 14 SOUTHERN RICE. Second Conf. on Rice Util- (145) WASSON, R. A., and WALKER, R. K. ization Proc, May 18-19. U.S. Dept. Agr., 1955. LOUISIANA RICE. La. Agr. Ext. Serv Ext Agr. Res. Serv. ARS 74-24, pp. 22-23. Pub. 1182, 16 pp., illus. WEIHING, R. M., MONCRIEF, J. B., DAVIS, W. C. (134) STANSEL, J. W., HALICK, J. V., and KRAMER, H. H. (146) and 1961. INFLITENCE OF TEZ^IPERATURE ON HEADING 1950. YEARLONG GRAZING IN THE RICE-PASTURE SYS- DATES AND GRAIN CHARACTERISTICS OF RICE. TEM OF FAEMING. Tex. Agr. Expt Sta Rice Tech. Working Group Proc, June 29 Prog. Rpt. 1280, 4 pp. (147) WILLIAMS, A. H. to July 1, Lafayette, La. MP 488, pn 14-15. 1952. PRE-HARVEST DRYING OF RICE BY CHEMICAL TREATMENT. Down to Earth 8(2) : 2-3 (135) STROMBERG, L. K., and YAMADA, H. (148) and FINFROCK, D. C. 1955. WATER Qt^ALITY IN RICE FIELDS. Calif Agr 9(3) : 10. 1962. EFFECT OF PLACEMENT AND TIME OF INCOR- (136) SLTLLIVAN, K. B. PORATION OF \^TCH ON RICE Y^IELDS. AgrOD Jour. 54(6) : 547-549. 1960. WATER IS A 'CROP' WITH ROTATION RESER- (149) FINFROCK, D. C, and MELLER, M. D. VOIRS. Ark. Farmer 62(8) : 4, illus. 1957. GREEN MANURES AND CROP RESIDUES IN (137) THOMPSON, W. R., and WALLER. T. :S1. MANAGING RICE SOILS. Calif. Agr. Expt 1952. GROWING RICE IN THE MISSLSSIPPI DELTA. Sta. Ext. Serv. Leaflet 90, 6 pp. Miss. Agr. Ext. Serv. Pub. 219, 0 pp. (150) WYCHE, R. H., and CHEANEY, R. L. (138) TELTON, E. W., and SCHKOEDER, H. W. 1955. WATER SEEDING OF RICE. Tex Agr Expt 1961. THE EFFECT OF INFRARED RADIATION ON IM- Sta. Prog. Rpt. 1778, 3 pp. MATURE INSECTS IN KERNELS OF ROUGH RICE Rice J (139) TLTLLIS, E. C. CAUTION.—If pesticides are handled or applied 1951. HERBICIDES FOR ACCELERATING MATURATION improperly, or if unused parts are disposed of im- OF RICE. South. Weed Conf. Proc 4: 1-2. properly, they may be injurious to humans, do- mestic animals, desirable plants, pollinating in- (140) UNITED STATES DEPARTMENT OF AGRICULTI^RE. sects, fish or other wildlife, and may contaminate 1957. CONTROLLING INSECT PESTS OF STORED KIC E. U.S. Dept. Agr. Agr. Handb. 129, 30 pp water supplies. Use pesticides only when needed illus. and handle them with care. Follow the directions and heed all precautions on the container label. WEEDS AND THEIR CONTROL By R. J. SMITH, JR., and W. C. SHAW Losses in the rice crop clue to Aveed competition improvement in rice yields were obtained in more amount to more than $60 million each j^ear. In than 90 percent of the fields treated in 1962. addition, farmers spend almost $24: million each Propanil controls barnyardgrass, including year to control weeds. Among the weeds that the species EchinochJoa cmsgaUi (L.) Beauv., E, cause severe losses in rice are barnyardgrass colonum (L.) Link, and E. cmispavonis (H.B.K.) [EchinochJoa spp.), red rice [Oryza sativa L.), Schult.; and other grasses, including crabgrass sigiialgrass {Brachiaria spp.), sprangletop {Lep- {Digitaria spp.), Texas-millet {Paniciim texanum tocKloa spp.), sesbania {Seshania exalt ata (Raf.) Buckl.), paragrass {P. puiyurascens Raddi), and Cory), curly indigo {Aeschynomene virginica signalgrass {Brachiaria spp.). Propanil also con- (L.) B.S.P.), Mexican-weed [Caperonia casta- trols certain young annual broadleaf weeds in- neaefolki (L.) St. Hil.), gooseweed [Sphenodea cluding sesbania, curly indigo, gooseweed, and zeylanica Gaertn.), redstem {Ammannia coc- redstem; and young annual sedges, including cínea Rottb.), ducksalad [H et er anthem spp.), spikerush, umbrellasedge, and Fimhristylis spp. bulrush [Scirpus ^^^.)^ umbrellasedge {Cyperus Propanil controls all these weeds most effectively spp.), spikerush [Eleocharü spp.), and various when they are in the early vegetative stage of species of algae. growth. Conditions favorable for growth of rice also Propanil kills the cells of grass-weed and are favorable for growth of these weeds. Weeds broadleaf-weed plants by contact action. It is in rice produce an abundance of viable seeds; and usually applied when both the weeds and the rice once weeds infest the soil, they are difficult to are in the early stages of development. Barn- remove. The best approach to weed control is to yardgrass and other grass weeds are controlled prevent Aveed infestations by seeding weed-free most eft'ectively when propanil is applied in the rice and by removing scattered weed seedlings 2- to o-leaf stage, or when the grass is 2 to 3 from the field before they produce seed. Even inches tall. However, rapidlj^ growing grass after weeds infest the soil, however, they can be weeds in highly fertile soil and deep water may effectively controlled by selected cultural and be controlled satisfactorily when the grass weeds chemical methods. have four or more leaves, Weed control is the primary aim of many cul- Propanil should be applied according to the tural practices. Herbicides—notably propanil developmental stage of the grass weed rather than and the phenoxy herbicides—have been used in that of the rice. However, a reasonably heavy conjunction with good farming practices for con- stand of rice should be growing before treatment; trolling weeds and have greatly increased the otherwise if replanting is necessary, the effective- effectiveness of the cultural practices. As chem- ness of the herbicide is lost. ical methods of weed control change—and they Irrigation stimulates the .?:rowth of grass weeds are changing rapidly—cultural practices also will and makes them more susceptible to propanil, but change. water should not be standing on fields when pro- panil is applied because propanil cannot reach Certain young grass and broadleaf weeds in weeds covered with water. Fields treated with rice were effectively controlled in 1959 bj^ pro- propanil should be flooded 1 to 4 days after treat- panil [3,4-dichloropropionanilide]. Propanil is ment to increase the activity of the herbicide on very selective, and rice is not injured by high barnyardgrass and to prevent barnyardgrass and rates applied soon after emergence. In 1961 rice other grass-weed plants from reinfesting the field. farmers in the major ricegrowing States used pro- Propanil may be applied with either ground or panil as a postemergence weed killer in commer- aerial equipment. Aerial equipment has the cial fields on about 20,000 acres. Because pro- advantage because fields may be sprayed when panil controlled grass weeds so effectively in 1961, the soil is too wet to support- ground equipment, and because it was recommended by the agricul- and also levees do not present a problem as with tural experiment stations in Arkansas, Missis- ground equipment. The spray solution of pro- sippi, and Texas, rice farmers treated approxi- panil should cover the weeds adecjuately and uni- mately 250,000 acres in 1962. Overall, goodyto- formly but should not be allowed to drift onto excellent grass and weed control and significant nearby areas where it can injure field crops such 111 MnacuvrvKï^ HANDBOOK 289, u.s. DEPT. OF AGRICULTURE 112 Water management affects the response of as cotton nnd soybeans and certain horticultural weeds to phenoxy herbicides. Herbicides are and ornamental plants. Young cotton and soy- bean plants are susceptible to propanil mitil they less effective in reaching weed plants that are covered by water, and herbicides cannot effec- are 8 to 10 inches tall and can be killed or injured tively control weeds that are growing slowly be- severely enou^ih to reduce yields greatly. Postemergence treatments with phenoxy herbi- cause of dry soil. Therefore^ herbicides should cides control most broadleaf and aquatic Aveeds be applied soon after draining, while weeds are and many sedges that infest rice. Grass weeds o-rowing rapidly. If the field is flooded too soon are not controlled. Phenoxy herbicides are often after spraying or if rain falls immediately after used by commercial ricegrowers, and more thaii spraying, 'the herbicide is washed off the weed half of the rice crop in the United States is plants and cannot control their growth. sprayed each year for broadleaf-weed control. Phenoxy herbicides are sprayed uniformly to Phenoxy herbicides used for controlling broad- the field with low-gallonage sprayers attached to leaf weeds in rice include 2,4-D [2,4-dichloro- ground or aerial equipment. Care must be taken phenoxyacetic acid], MCPA [2-methyl-4-chloro- not to injure other crops such as cotton, soy- phenoxyacetic acid], 2,4,5-T [2,4,5-trichlorophe- beans, and tomatoes and valuable trees, shrubs, noxyacetic acid], and silvex [2-(2,4,5-trichloro- and ornamental plants. All major rice-produc- phenoxy)propionic acid]. These herbicides are ing States strictly regulate aerial applications of applied as either amine salt or low-volatile ester phenoxy herbicides. Most States regulate ground formulations at rates of i/o ^^ IV2 pounds per acre applications. These laws prohibit the use of acid equivalent. The rate depends on the weed high-volatile esters of 2,4-D, MCPA, 2,4,5-T, and species and the stage of growth of the rice. silvex. Definite regulations as to equipment, Response of rice to phenoxy herbicides is af- herbicide formulations, wind velocity, records, fected chiefly by the stage of development of the responsibility, and liability must be observed. rice plant. ^Very young rice is injured severely Before spraying rice with postemergence herbi- or even killed by^ 2,4-D, MCPA. 2,4,5-T, and cides, farmers and custom applicators should be- silvex. Rice in late-jointing, boot^ing. or heading come familiar with State laws so they can com- stages may be injured severely, üice 111 ine latr- ply with them. tillering or prejointing stages is usually unin- jured by phenoxy herbicides. Rice responds CAUTION.—Before being used for applying insecti- differently to these various postemergence herbi- cide or fungicide, spray equipment that has been used cides. It^ is most ^^tolerant^' to 2,4,5-T, less '^tol- for applying 2,4-D, 2,4.5-T, MCPA, or silvex should be erant'' to silvex and MCPA, and least ^^tolerant'^ given a special cleansing with ammonia or with acti- yaied charcoal and detergent. For detailed instruc- to 2,4-D. tions, consult your State extension weed specialist. Weeds also respond differently to 2,4-D, MCPA, 2,4,5-T, and silvex. When several spe- cies varying in susceptibility to a herbicide are Certain algae maj^ be controlled with applica- present 'in one ricefiekh mixtures of phenoxy tions of small copper sulfate crystals applied in herbicides may be used advantageously. Weeds the early stages of scum development. Differ- are usually most susceptible to phenoxy herbi- ences in the species of algae and in local water cides when they are young and growing rapidly. and soil conditions determine the amount of con- Therefore, it is important to treat weeds as soon trol possible. Copper may be toxic to fish, so as the rice is adequateh^ ''tolerant" to the herbi- care must be taken if water from treated rice- cide—usually about 7 weeks after rice emerges. fields is collected in reservoirs containino; fish. RECE DISEASES Bv J. (T. ATKINS Rice diseases are economically important in disturbances reported from Japan and other Asi- the rice crop in the southern rice area (o).^ Ex- atic countries. A few^ minor diseases caused by cept for seedling disorders, these diseases are of no fungi are also not known to occur ni the United importance in California. Annual losses in Loui- States. siana and Texas average about S percent. Dis- The severity of specific diseases is influenced by eases are important in rice, but they are not as varietal susceptibility, fertilization, soil type, and disastrous in rice as in many other crops. Al- environmental conditions. Losses from certain though average losses in most fields are rather diseases can be reduced or held to a low level by low, losses in individual fields from specific dis- the use of resistant varieties, better cultural and eases are sometimes high. management practices, and seed treatment. Dis- Most of the world's important rice diseases are eases shift in prevalence and severity with known to occur in the Ignited States. Excep- changes in varieties. The reaction of 18 rice tions are the rice dwarf and rice stripe viruses, varieties to some diseases in the ITnited States bacterial leaf blight, and certain physiological are shown in table 19. TABLE 19.—Reaction of rice varieties to some diseases of rire in the United States [R = resistant; MR = moderately resistant; ]\IS = moflerately susceptible; S = susceptible; VS = very susceptible] Browm leaf Narrow brown Straighthead White tip Hoja blanca Grain type and variety Blast spot leaf spot Sîiort-èTain : Caloro S S S S S S Cody S S S S S S Colusa S MS S S S R MediurD-grain : Arkrose s S s s VS R Cairo se VS MS MS s VS S Gulf rose R, S MS R s s R MagnoUa S MS S s s S Nato s MS MS MS s S Northrose s S S MR s MR Zenith R, S MS s S s S Long-grain ; Belle Patna S S S R R S Bluebonnet 50 MS S s R R S Century Patna 231 __ S s MS VS R s Rexoro s s y S VS R s Sunbonnet MS s s VS R s Texas Patna S s VS R R s Toro s s MS R R s TP 49 s s MS VS R s Major Diseases shortl}^ after rice was introduced into South Carolina [M) and then into Louisiana [18). Slast Losses from blast were light from about 1985 to 1955; however, in the southern rice area, par- Blast, caused by the fungus Piricidaria ory- ticularly Louisiana, seriously infested fields have zae Cav., occurs in all ricegrowing areas of the l)een found each year since *1955 (5). Blast has world and is the most damaging disease of rice Ijeen one of the chief factors in preventing suc- (fig. 39). Blast in the United States is about as cessful rice culture in southern Florida» old as the rice crop itself—it caused trouble When the fungus attacks the leaves, the dis- ease results in leaf blast. Symptoms are elon- 1 Italic numbers in parentheses refer to Selected Refer- ences, p. 120. o-ated or spindle-shaped leaf spots with grayish 113 114 AGRICULTURE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE Eice plants under high levels of nitrogen fer- tilization are susceptible to blast. Plants grow- ing under nonflooded or upland conditions are more susceptible than those growing under flooded or irrigated conditions {19). For this reason, blast is often heavier on the levees and on or around knolls or other high areas in the ricefield than it is on the low areas. All United States rice varieties are susceptible to one or more of the 10 pathogenic races of P. oryzae known to occur in the southern rice area (^, 20). However, Rexoro, Texas Patna, and TP 49 usually escape infection because they are late maturing. Under average field conditions. Blue- bonnet 50 and Sunbonnet are less severely in- fected than are several other varieties, and losses are lighter. Arkrose, Caloro, Calrose, Colusa, Nato, and Northrose are consistently susceptible. Gulfrose and Zenith are resistant to most races. FIGURE 39.—The long, narrow spots on the leaves and the The reaction of 18 varieties to 10 races is given infection at the hase of the panicle, which caused it to in table 20. break over, are typical symptoms of blast. (Photo cour- te.sy of G. E. Templeton. ) Brown Leaf Spot Brown leaf spot of rice is caused by Helmin- centers and brown margins. Under severe dis- thosfO'ñum oi^zae B. de Haan, the same fungus ease conditions, nearly all leaves are killed and that causes seedling blight. The spots occur many young plants are killed or severely dam- chiefly on the leaves but are frequently on the aged. Young plants are also killed by infection hulls (fig. 40). The leaf spots are oval to cir- of the sheath tissues, which turn brown. Gener- cular and grayish brown to black. ally, all plants in a ricefield are not uniformly Brown leaf spot is prevalent in the southern affected. In some areas the plants are killed, rice area. Under good cultural conditions, dam- but in others they are affected less severely. age is slight on vigorous plants. Weak plants The leaves are susceptible from the seedling with yellowish leaves, caused by low nitrogen through the early-tillering stage of growth. Un- levels, root damage, or other factors unfavorable der flooded soil conditions, the leaves are less for good nitrogen nutrition, are often severely susceptible in the late-tillering stage of growth damaged by brown leaf spot. and at heading. As a result, severely diseased All commercial rice varieties are susceptible to fields of young rice appear to recover later when brown leaf spot. Bluebonnet 50 is generally the plants become older and progress through more susceptible than are most other varieties. the vegetative growth stages. Management and fertilizer practices that pro- Head blast, also called rotten neck, results mote good growth reduce losses. from the attack of the fungus after emergence of the panicle (head) from the boot or top leaf Narrow Brown Leaf Spot sheath. The peduncle (the top node and inter- Narrow brown leaf spot in rice, caused by the node) and the branches of the panicle are very fungus Cercospora oryzae I. Miyake, is one of susceptible to attack. Typically, the peduncle the most prevalent rice diseases in the southern shows a necrotic, brown area that prevents move- rice area. The leaf spots are narrow or linear ment of food into the developing grain. The and light to dark brown (fig. 41). When se- grain produced in affected panicles varies from vere, the leaves die, one after another, beginning nearly normal amounts to none, depending on with the lower leaves. In most seasons, infec- the time of infection in relation to flowering. tion does not become severe until late August or As infection weakens the structural tissues of September. Early-maturing rice varieties, when the peduncle, the panicles frequently break over sown early, tend to escape heavy infection. to give the condition known as rotten neck. Rice varieties show marked differences in sus- Atmospheric moisture conditions are of pri- ceptibility. Several pathogenic races or strains mary importance in infection and spread of the of 0. oryzae occur in the United States [îS). fungus that causes blast (19). Frequent rains, Bluebonnet 50, Rexoro, and Texas Patna are heavy nightly dews, and high relative humidities susceptible varieties. Under average field con- favor disease development. Severe outbreaks of ditions. Century Patna 231, Gulfrose, Nato, Toro, the disease occur after periods of rainy weather. and TP 49 are fairly resistant. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 115 TABLE 20.—Reaction of rice varieties to the races of Piricularia oryzae Cav. in the United States [R = resistant : MR = moderately resistant ; S = susceptible] Race Grain type and variety 10 16 Short-grain : Caloro R s S s R S s s R Cody R MR S s R S s s R Colusa R S s s R S s s R Medium-grain : Arkrose R s s s R s s s R Calrose R s s s R s s s R Gulf rose S R R R R R s R R R Magnolia R R S R R S s R R S Xato R R s R R s s R R S Xorthrose R S s S R s s R R S Zenith S R R R R R s R R R Long-grain ; Belle Patna S R S R R S s S R R Bluebonnet 50 s R s R R s R R S Century Patna 231- s R s R R s MR R R R Rexoro s R s R R s s S R R Sunbonnet s R s R R s s S R Texas Patna s R s R R s s s R R Toro s R s R R s s s R S TP49 s R s R R s s s R R ä J II. '4' FIGURE 41.- -Linear lesions on rice leaves are symptoms of narrow brown leaf spot. Root Rot Root rot of rice is a general diseased condi- tion in which the roots grow poorly, darken with necrosis, or die. As decay progresses, the leaves FiGUEE 40.—Oval to circular lesions on rice leaves are cease to grow normally and turn yellow. Af- symptoms of brown leaf spot. fected plants generally show heavy brown leaf 116 AGRICULTURE HANDBOOK 289, U.S. DEFÏ. OF AGRICULTURE spot because of their impaired physiological condition. Several soil fungi may cause root rot. Damage is more severe when nematodes and. root mag- gots feed on the roots. Plants growing ni sahne soil and alkali spots in ñelds are also affected. Losses from root disorders can be held to a mimmum through good cultural and fertilizing practices that maintain the plants in a vigorous condition. Draining the field and permitting the soil to dry stimulates growth of new roots. For many years growers have used this ]:iractice to control' root maggots and straighthead hi con- junction with topdressing applications of nitro- gen. Seedling Bligh*) Fungi in the soil and on or in the seed cause seedling blight of rice (fig. 42). These fungi reduce emergence and kill or weaken tlie plant after emergence. Low soil temperature and high soil moisture, combined with seedlwrne fungi, or combinations of tne two, make stand establish- ment difficult. Satisfactory stands are generally obtained through use of good-quality seed treated with a fungicide and seeded under conditions favor- able for rapid emergence. Atkins, Cralley, and Chilton (7) reported that thiram, chloranil, dichlone. and a number of organic mercuii'S gave best results. Seedling blight caused by Helmm- thospor/iim nryzne—the fungus that causes brown leaf spot—can be partly controlled by using one of the mercury fungicides. Each of the chemicals listed is available m différent preparations. FIGURE 42.—Three blighted rice seedlings and, at right, a healthv seedling. WARNING The materials recommended here for treating rice seed should be considered poisonous to man and ani- mals. Care should be taken in handling and using them. Read the label placed on each container by the manufacturer and follow his instructions regarding safet}' measures. All workmen operating seed-treating equipment should be carefully taught how to use the chemicals and should be warned against carelessness. Sacks of treated seed should always be properly la- beled. Care should be taken to prevent any treated seed from being used as food or feed. Stem Rot The stem rot fungus Leptospluteriu salvinU Catt. {Sderothim oryzae C'att.) lives in the soil as sclerotia from one season to another up to 6 years (SO) (fig. 4?,). Typically, rice plants are attacked in the advanceil-growth stages. Ini- tially, the fungus invades the sheath tissues near the water level and produces dark areas. The FIGURE 43.—Rice culms showing sclerotia of the stem rot fungus. (Photo courtesy of G. E. Templeton.) RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 117 ñuigus progresses inward to the culm. The general, rice grown on the lighter or sandy soils nodes aucl internodes turn dark and weaken. is more subject to straighthead than nee grown Many of the plants lodge because of rotten culms. on the heavier clay soils. The plants are weakened or killed before ma- For many years, ricegrowers have followed the turity. Little gi-ain is produced and its quality practice of draining and drying the soil to pre- is reduced. vent straighthead {'27). The fields are drained, None of the rice varieties are highly resistant dried, and reflooded just before panicle forma- to stem rot {H). Rexoro is jjerhaps the most tion. This period is about 50 days after seedling susceptible variety. Some of the medium-grain emergence for Century Patna 2.31, a susceptible, varieties are resistant or intermediate in reaction. early-maturing variety [1^). However, the best The early-maturing varieties tend to escape se- control measure is to use resistant varieties. vere damage if seeded early. High rates of The numerous rice varieties have been classi- nitrogen fertilizer increase the susceptibility of fied as to straighthead reaction [6). Belle Patna, plants to stem rot damage, but potassium fer- Bluebonnet 50, Lacrosse, Texas Patna, and Toro tilizers reduce damage. are resistant. Nato is intermediate in reaction and is seldom affected. Straighthead White Tip Straighthead, sometimes called blight, is a non- parasitic or physiological disease of rice. Diag- White tip of rice is caused by an ectoparasitic, nostic symptoms are observed only in the panicles. foliar nematode, Aphelenchoides hevseyl Christie The panicles remain upright at maturity because (fig. 45). The nematodes are seedborne and live of lack of grain development (fig. 44) ; hence, from one crop to the next in the seed rice. After the common name of straighthead. The shape rice is sown, the nematodes become active and of the palea and lemma, which later form rhe move into the growing point of the young rice hulls, is distorted, particuarly in the long-grain plants. In this protected location, the nematodes varieties. It is similar to a parrot beak, crescent, feed and reproduce. The feeding by large num- or half moon. Hull distortion may or may not bers of nematodes injures the developing leaves be conspicuous in the short- and medium-grain and panicles before emergence. The nijury is varieties. later observed as white, necrotic leaf ú\y?> and Straighthead is caused by unknown soil con- small, usually sterile panicles. Grain yields in ditions associated with prolonged submergence susceptible plants are greatly reduced. of the soil with water. TJndecayed organic ma- Several methods may be used to control white terial and arsenic in the soil are also factors. In PiGUBE 44.—Erect panicles with sterile florets are typi- FIGURE 45.—Left, healthy rice panicle; right, panicle cal of rice plants affected with straighthead. affected with white tip. 118 AGRICULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE tip Resistant varieties or nematode-free seed The panicles are reduced in size and often fail may be sown. Cralley (16) and Todd and At- to emerge completely from the boot. The palea kins (S5) have described hot-water treatments and lemma are generally distorted in shape and that control white tip very effectively. They are later turn brown. Most florets are sterile. Since not practical for general use. However, they the diseased plants produce few, if any, seed, the can be used by the rice experiment stations for panicles remain upright instead of bending over treating small lots of base seed used in founda- like those of normal plants (fig. 47). tion seed programs. Emergence through water Hoja blanca occurs only in the Western Hemi- following water seeding controls white tip (16). sphere. Leaf symptoms are similar to those of This practice can also be used to clean up small the stripe virus disease of Japan, but the two diseases differ (5). Hoja blanca was first recog- lots for seed production. Several rice varieties are resistant to white tip nized as a new rice disease in 1956 {2). Severe (table 1). In general, the long-grain varieties yield losses were reported from Cuba, Venezuela, are resistant and most of the short- and medium- "and other countries of Latin America. The dis- grain varieties are susceptible (12). Although ease and insect vector were found in 1957 in white tip was an economically important dis- f'lorida (5), in 1958 in southern Mississippi (iO), ease in the southern rice area for many years, it and in 1959 in Louisiana {11). An eradication program was initiated after each finding of the is no longer important. insect vector. In 1960 and 1961, neither the dis- ease nor the insect vector was found in the south- Minor Diseases ern rice States. In 1962, ,6'. orizicola was again found and collected in southern Louisiana \l). Bordered Sheath Spot Yield losses from hoja blanca in the United Bordered sheath spot in rice is caused by States have been negligible. LTnless the disease Rhizoctonia oryzae Ryker & Gooch. The sheath and insect vector become established and cause spots are large, 2 to 6 centimeters long, and fre- economic losses, no control measures need be con- quently encircle the sheath. The margins of the spots are reddish brown. During wet weather, the leaves of rice plants in small areas, 2 to 6 feet in diameter, are killed by Rhizoctonia spp. Hoja Blanca Hoja blanca, or white leaf, is a virus disease of rice that is transmitted by a planthopper, Sogata orizicola Muir. Leaf symptoms are one or more white stripes along the leaf blade or a whitening of the entire leaf blade (fig. 46). Diseased plants are generally reduced in height. FiGUEE 46.—Rice leaves affected with hoja blan ca. FiQUEE 47.—Rice panicles affected with hoja blanca. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 119 sidered by individual rice producers. Arkvose, varieties, except Nato, generally show less kernel Colusa, and Gulfrose are resistant to hoja blanca. smut. Kernel Smut Kernel Spots Kernel smut of jice is caused by one of the Discolored or dark areas and spots occur on smut fungi, Neovossici harclayana Bref. (SI). the kernels of brown and milled rice. This ker- Part or all of the endosperm is replaced by a nel discoloration is generally associated with black mass of smut spores (fig. 48). One to sev- dark, discolored hulls. Ourvularia lunata eral grains per panicle are affected. Other plant (Wakk.) Boed., Fusarium spp., Altemariaj.p])., parts are not affected. The disease is easily over- Trichoconis caudata (Appel & Strunk) Clem- looked in the field. It can be seen when rains ments, and Helminthosporium oryzae are the wash the black spores over portions of the pani- fungi most commonly isolated [29)., - , Feeding cle or when the smut spore mass expands between punctures of the immature grains by stink bugs the two hulls with absorption of moisture from also cause kernel spots {17). dew or rain. At the time of some of the earlier studies The black smut spores germinate and produce {21, 26. 29), rice was binder harvested and sporidia. When the rice flowers open at pollina- placed in shocks. The change in harvesting tion, the sporidia enter. The fungus then invades methods from the binder to the combine has the developing grain, grows, and produces its probably reduced losses from kernel spots. spores. Infection is not systemic in the rice plant, as it is with several other cereal smut fungi Leaf Smut {2I^). Although the smut spores are seedborne Leaf smut, caused by EntyJoma oryzae H. & P. (that is, they are carried into a field along with Syd., is a common but minor rice disease in the the seed), they are not directly responsible for southern rice area (fig. -19). The disease may be later smut infection. Kernel smut is more preva- recognized by numerous, small, black sori on the lent in rainy seasons and in fields receiving fairly leaves. The disease becomes more prevalent as high rates of nitrogen fertilizer {"25). Nitrogen the rice plants approach maturity. applied late in the season also increases the inci- dence of kernel smut. No satisfactory controls for kernel smut are known at present. Seed treatment by chemicals or hot water is ineffective. All long-grain varie- ties are susceptible. Most of the medium-grain i '< Í ■ j P^ ' ' 1 •! \ ■ .ñ, FiouKE 48.—Rice panicle with several florets affected by kernel smut. FiGUBE 49.—Leaf smut on rice leaves. HANDBOOK 2 89, U.S. DEFT. OF AGRICULTURE 120 A';mTr'Fi;nTKE (16) Selected References 1956. A NEW CONTROL MEASURE FOR WHITE TIP. Ark. Farm Res. 5(4) : 5. (1) ANONYMOUS (17) DOUGLAS, W. A., and TULLíS, E. C. 1962. INSECT CAKKIER OF HOJA BLANCA KICK DIS- 1950 INSECTS AND FUNGI AS CAUSES OF PECKY EASE BEAPPEARS IN LOUISIANA. Rice Jour. RICE. U.S. Dept. Agr. Tech. BuL 1015, 20 65(12) : 22. PP- (2) ADAIK, C. R., and INGRAM, J. W. (18) FULTON, H R. 1957. PLANS FOR THE STUDY OF HOJA BLANCA—A 1908 DISEASES AFFECTING RICE IN LOUISIANA. LA. NEW RICE DISEASE. Rice Jour. 60(4) : 12. Agr. Expt. sta. Bul. 105, 28 pp. (3) ATKINS, J. G. _ , (19) KAHN, R. P., and LIBBY, J. L. 1958. RICE DISEASES. U.S. Dept. Agr. Farmers 1958. THE EFFECT OF ENVIRONMENTAL FACTORS AND Bui. 2120, 14 pp. PLANT AGE ON THE INFECTION OF RICE BY (4) THE BLAST FUNGUS, PIRICULARIA OEYZAE. 1962. PREVALENCE AND DISTRIBUTION OF PATHO- Phytopathology 48: 25-30. GENIC RACES OF PIRICITLARIA OEYZAE IN THE (20) LATTEEELL, 'FRANCES M., TULLíS, E. C, and COL- UNITED STATES- Pîiytopathology 52 : 2. LIER, J. W. (5) and ADAIE, G. R. I960 PHYSIOLOGIC RACES OF PIRICULARIA ORYZAE 1957. RECENT DISCO\^RY OF HOJA BLANCA, A NEW CAV. Plant Dis. Rptr. 44: 679-683. RICE DISEASE IN FLORIDA, AND VARIETAL RE- (21) MARTIN, A. L., and ALSTATT, G. E. SISTANCE TESTS IN CUBA AND VENEZITELA. 1940. BLACK KERNEL AND WHITE TIP OF RICE. Plant Dis. Rptr. 41: 911-915. Tex. Agr. Expt. Sta. Bui. 584, 14 pp. BEACHELL, H. M., and CRANE, L. E. (6) (22) METCALF, H. 1956. REACTION OF RICE VARIETIES TO STRAIGHT- 1906. A PRELIMII^AEY REPORT ON THE BLAST OF HEAD. Tex. Agr. Expt. Sta. Prog. Rpt. RICE WITH NOTES ON OTHER RICE DISEASES. 1865, 2 pp. S.C. Agr. Expt. sta. Bui. 121, 48 pp. CRALLEY, E. M., and CHILTON, S. J. P. (7) (23) RYKER, T. C. 1957. UNIFORM RICE SEED TREATMENT TESTS IN 1943. PHYSIOLOGIC SPECIALIZATION IN CERCOSPORA ARKANSAS, LOUISIANA, AND TEXAS. Plant ORYZAE, Phytopathology 33 : 70-74. Dis. Rptr. 41: 105-108. (24) TEMPLETON, G. E. (8) GOTO, K., and YASITO, S. 1961. LOCAL INFECTION OF RICE FLORETS BY THE 1961. COMPARATIVE REACTIONS OF RICE VARIETIES KERNEL SMI^T ORGANISM, TILLETIA HÓRRIDA. TO THE STRIPE AND HOJA BLANCA VIRUS Phytopathology 51 : 13(V131. DISEASES. Internl. Riœ Conin. Newsletter (25) JOHNSTON, T. H., and HENRY, S. E. 10Í4) : 5-8. 1960. KERNEL SMUT OF RICE Ark. Farm Res. JoDON, N. E., and BOLLICH, C. N. (9) 9(6) : 10. 1962. TESTING AND BREEDING FOR BLAST-RESISTANT (26) TiSDALE, W. K. RICE. La. Agr 5(4): 14-15. 1922. SEEDLING BLIGHT AND STACK-BURN OF RICE (10) KRAMER, J. P., and HENSLEY. S. D. AND THE HOT-WATER SEED TREATMENT. U.S. 1958. HOJA BLANCA AND ITS INSECT VECTOR FOUNT Dept. Agr. Dept. Bui. 1116, 11 pp. ON RICE IN A SECOND AREA IN THE UNITED and JENKINS, J. M. STATES. Plant Dis. Rptr. 42: 14Ui 1921. STEAIGHTHEAD OF RICE AND ITS CONTROL. XEWSO^í. L. D., SPINK, W. T.. and others, (11) U.S. Dept. Agr. Farmers' BuL 1212, 16 1960. OCCl^RRENCE OF HOJA BLANCA AND ITS VEC- TOR, SOGATA ORIZICOLA MUIR, ON RICE IN pp. LOUISIANA. Plant Dis. Rptr. 44: 390-393. (28) ToDD, E. H., and ATKINS, J. G. 1959. WHITE TIP DISEASE OF RICE. II. SEED TREAT- and ToDD, E. H. (12) MENT STUDIES. Phytopathology 49: 184- 1959. WRITE TIP DISEASE OF RICE. TIT. YIELD TESTS AND VARIETAL RESISTANCE. PhytO- 188. (29) TULLíS, E, C, patholog^^ 49 : 189-191. 1936. FUNGI ISOLATED FROM DISCOLORED RICE KER- (13) CHEANEY, R. L. NELS. U.S. Dept. Agr. Tech. Bui. 540, 11 1955. EFFECT OF TIME OF DRAINING OF RICE ON THE pp.. PREVENTION OF STRAIGHTHEAD. TeX. Agr. (30) and CRALLEY, E. M. Expt. Sta. Prog, Rpt. 1774, 5 pp. 1941. LONGEVITY OF SCLEROTIA OF THE STEM-ROT (14) CRALLEY, E. M. FUNGUS LEPTOSPHAERIA SALVINII. PhytO- 1936. RESISTANCE OF RICE VARIETIES TO STEM ROT. pathology 31: 279-281. Ark. Agr. Expt. Sta. Bui. 329, 31 pp. (31) and JOHNSON, A. G, (15) 1952, SYNONYMY OF TILLERTIA HÓRRIDA AND NEO- 1949. WHITE TIP OF RICE. (Abstract) Phyto- vossiA BAEci^YANA. Mycologla 44: 773- pathology 39: 5. 788. INSECTS AND THEIR CONTROL By TRAVIS EVERETT Rice Water Weevil The rice water weevil can be effectively con- trolled with insecticides. The rice water weevil {L/sso)'hopfnts ory- zophilvs Kuschel) occurs in most of the rice- Rice Stink Bug growing areas of the United States. The adult weevil (fig. 50) is grayish brown and about one- Practically all ricefields in Arkansas. Louisi- eighth inch long. It overwinters in finely matted ana, and Texas are infested with tlie rice stijik grasses growing in the vicinity of ricefields. In bug (Oebalufi pugnax (Fabricius) ). The adult the spring it migrates into the ricefields and stink bug (fig. 51) is a straw-colored, shield- feeds on newly emerged plants, making slitlike, shaped insect about one-half inch long. It passes longitudinal feeding scars on the upper surface the winter as an adult in the refuse near the sur- of the leaves. Eggs are laid in the leaf sheaths face of the ground in clum])s of grass. It emerges of rice plants. Larvae feed on the roots of rice from winter quarters in the spring and feeds on plants and cause severe injury by pruning the grasses and sedges. Two or tliree generations root svstem. The voung larvae, or root maggots may be produced tliere before it migrates to rice as they are commonly called, are milky white, soon after the rice begins to head. The eggs, legless, and about one-half inch long when fully shaped like short cylinders, are deposited on the grown. leaves, stems, or heads of the rice, on grass, on Since the innnature stages of the rice water Mexican-weed, and on other weeds. The eggs weevil are spent entirely under water among the are usually laid in clusters of 10 to 40 in 2 rows, rice roots, many of the larvae may be destroyed by drainage (6).^ However, this practice is not recommended for controlling the root maggots because it is unreliable and also impractical in areas where water supplies are not abundant. 1 Italic numbers in parentheses refer to Selected Refer- ences, p. 124. FIGURE 50.—Adult rice water weevil. riGURE 51.—Adult rice stink bug. 121 122 AGRICULTURE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE are green when first laid, and change to reddish black before hatching. The freshly hatched nymph is nearly round, about IV2 millimeters long and 1 millimeter wide. The head, thorax, legs, and antennae are black; the abdomen is red with two elongate black spots running crosswise. The young stink bugs remain together near the eggshells until after the first molt. Then they seek separate feeding places, generally on grass or on rice panicles, where they suck the juice from the developing kernels. Feeding in the milk stage of rice produces empty glumes, where- as feeding in the soft-dough stage causes "pecki- ness" of grain or seed sterility (4-)- Since infestations build up on grasses earlier in the season, control of grasses in the field and mowing the areas around the field help reduce the potential population for infesting rice. Two hymenopterous egg parasites, Ooencyrtus anasae (Ashm.) and Telenomus pod Is/ Ashm., are at times very helpful in reducing stink bug popu- lations late in the season. Grape Colaspis The grape colaspis [Maecolaupis fa vida PiGUKE 52.—Fall armyworm : A, Male moth ; B, right (Say)), called lespedeza worm by ricegrowers, front wing of female moth ; C, moth in resting posi- tion ; D, pupa ; E, full-grown larva. A, B, D, E about sometimes reduces plant stands severely in Arkan- X 2 ; C Slightly enlarged. sas and Louisiana (9). It passes the winter in the young larval stage. In the spring the larvae make their way toward the soil surface where widely separated localities. It feeds on leaves they feed on germinating seeds or seedlings. and stems of unflooded rice. Submerging the Heavy infestations may reduce stands so severely rice crop is usually effective in controlling this that reseeding is necessary. The larvae pupate insect. in the soil and emerge as pale brown, elliptical The rice stalk borer {Chilo plejadeUus Zincken) beetles about one-eighth inch long. Adults of (fig. 53) and the sugarcane borer {Diatraea sac- the grape colaspis lay their eggs in the soil charaUs (Fabricius) ) (fig. 54) both occur in rice- around the roots of grasses growing in lespedeza or other leguminous crops. Rice planted follow- ing these crops is subject to damage. Other Pests of Rice Several otner pests occasionally cause serious damage to rice. The rice leaf miner {HydreUia gríseola var. scapula.vs Loew) is a pest of rice in California (7). Maggots of this fly feed in the leaves of young rice plants and destroy the leaf tissue. Infested leaves turn brown and lie prostrate on the water. This pest is seldom present in suffi- cient numbers to warrant control measures. Gra.sshoppers are found in nearly all ricefields but seldom are present in sufficient numbers to cause severe damage (í2). They feed on the leaves, culms, and grain of rice. Sporadic outbreaks of the fall armyworm {^podoptera jrugiperda (J. E. Smith)) (fia 50) have been recorded at irregular intervals and ni FiQUEE 53.-Rice stalk borer: A, Adult; B, larva. About X 3. RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 123 1^ FiQtTRE 54.—Adult female sugarcane borer. / fields in Louisiiinii and Texas {S). These borers tunnel inside the stem throughout the growing FiGxniE 55.—Chinch bugs. Enlarged. season and interfere with normal growth and development of the plant. They may also weaken the stem so that it breaks off" or lodges before the number of bugs emerging the following harvest. Stalk borer damage is first noticeable spring. on the rice plant at time of heading when sterile The tadpole shrimp (Triops Jongicaudittus heads with white panicles, or white heads as they (LeConte) ). although not an insect, is sometimes are commonly called, appear. The eggs of both a pest in California (10). Damage occurs shortly species of borers are parasitized by the minute after fields are flooded and when eggs laid in wasp (Trichogramma minutum Riley), which fields the previous year hatch. Shrimp larvae helps reduce insect populations. Plowing under at first feed on organic matter in the soil; but rice stubble in the spring destroys some of the as they mature, they dislodge and feed on young overwintering borers. Grazing with cattle or rice piants. The shrimp matures in 8 to 10 days flooding rice stubble fields reduces the number of and may produce a second generation. hibernating borers. Eicefields should be separated For information on the insecticides currently as far as possible from corn and sugarcane be- recommended for control of rice insects, consult cause these two crops serve as a breeding place your county agent. State agricultural experiment for the sugarcane borer. station, or "the U.S. Department of Agriculture, The planthopper (Sogata orizicola Muir IS Washington. D. C. 20250. potentially a very important pest of rice. It is the only known vector of hoja blanca, the rice PRECAUTIONS disease that has become the scourge of rice pro- duction in several Latin American countries. Insecticides are poisonous. Use them only *S', orizicola was first reported in the United when needed and handle them with care. Fol- States in 1957. Although the planthopper was low the directions and heed all precautions on found in Mississippi in 1958 and in Louisiana in the container label. Insecticides should be kept 1959 [1) and in 1962, neither it nor the disease it in closed, well-labeled containers, in a dry place transmits has become established in the United where they will not contaminate food or feed States. Apparently the vector cannot survive the and where children and pets cannot reach them. cold weather that sometimes occurs in the rice- Avoid repeated or prolonged contact with skin growing areas of this country. and inhalation of dusts and mists. Methyl The chinch bug (Blissus leucopterm (Say)) parathion and phosphamidon should be applied (fig. 55) is present in Arkansas, Louisiana, and only by persons experienced in handling and ap- Texas (S). It has entered ricefields in large plying poisonous chemicals. Operators exposed numbers and seriously injured the young rice to sprays containing methyl parathion and phos- plants before they were submerged. Both adults phamidon should wear half masks equipped with and nymphs attack rice. The feeding of bugs cartridges of a type approved by the U.S. De- causes the plants to wither and die. Chinch partment of Agriculture. "Wear clean, dry cloth- bugs feed mainly on the stems, just above the ing, and wash hands and face before eating or surface of the ground. They may be controlled smoking. When handling concentrates, avoid by submerging the infested field. The insects spilling them on the skin and keep them out of spend the winter in dry grass, straw, and other the eyes, nose, and mouth. If any is spilled, material that affords them shelter. Plowing un- wash it off the skin and change clothing immedi- der such material in the fall or winter reduces ately. If it gets in the eyes, flush with plenty 124- .u;i:ií'iM;n .LV:;i>nOi)K 2SÖ, L.S. DEFT. Oi^ A(;RICULTURE of water for IT) niiiiutes and i^et mcMlical atten- Seiected References tion. (1) ATKINS, J. G., NEWSOM, L. D., SPINK, W. T., and Avoid drift of insectic'id.e s())-ays or dusts to jthers. nearby crops, livestock, or bee yards. Sp/^ays or IÍM;(). 0<'(_ rKKKNCK OF HOJA BLANCA AND ITS INSECT dusts applied hy airplane and olher power equip- VECTOE, SOGATA ORIZICOLA MUIR, ON EICE IN ment are especially likely M) drift. J>o not allow LOUISIANA. Plant Dis. Rptr. 44: 390-393. (2) BOWLING, C. C. poultry, dairy animals, jr meat animals to feed 19()(). CONTROL OF lííCE STINKBUGS AND GRASSHOP- on plants or drink water contaminated by drift PERS ON RICE. Tex. Agr. Expt. Sta. Prog of insecticides. Do not clean spraying equipment Rpt. 2132, 6 pp. or dump excess spi'cy material near streams, ^3) DouGiAs, W. A., and INGRAM, J. W. 1942. RICE FIELD INSECTS. U.S. Dept. Agr. Cir lakes, or ponds. 632, 32 pp. Do not apply— (4) and TULLíS, E. C. Aldrin or maiathion within 7 da3's before 1950. INSECTS AND FUNGI AS CAUSES OF PECKY RICE. U.S. Dept. Agr. Tech. Bui. 1015, 20 harvest. pp. (\irbaryl (Sevm) '^ within l-i days before (5) GRIGARICK, A. A., LANGE, W. H., and FINFROCK harvest. D.C. Metliyl parathion witlim IT» days before har- 1961. CONTROL OF THE TADPOLE SHRIMP, TRIOPS LONGICAUDATUS, IN CALIFORNIA RICE FIELDS. vest. Jour. Econ. Ent. 54: 36-40. Phosphamidon witliin :il days before harvest. (6) IsELY, DwiGHT, and SCHWARDT, H. H. Diekirin within oO days before harvest. 1934. THE RICE WATER WEEVIL. Ark. Agr. Expt Do not apply DDT to rice after heads start sta. Bui. 299, 44 pp. (7) LANGE, W. H., JR., INGEBRETSEN, K. H., and DAVIS to form. L. L. Do not feed rice straw to dairy animals or ani- 1953. RICE LEAF MINER. Calif. Agr. 7(8) : 8-9. mals being finished for slaugliter if the rice straw (8) PoRTMAN, R. F., and WILLIAMS, A. H. has been treated with DDT, phosphamidon, or 1952. CONTROL OF MOSQUITO LARVAE AND OTHER toxaphene. PESTS IN RICE FIELDS BY DDT. Jo'ir. Econ. Ent. 45: 712-716. Do not feed rice stravr to livestock if the rice (9) RoLSTON, L. H., and ROUSE, PHIL. straw was treated with aldrin within 30 days of 1960. CONTROL OF GRAPE COLASPIS AND RICE WATER harvest or with diekirin within ::!i) davs of harvest. WEEVIL BY SEED OR SOIL TREATMENT. Ark. Agr. Expt. Sta. Bui. 624, 10 pp. (10) ROSENBERG, L. E 2 Sevin should not be applied to rice that has been or 1947. APUS AS A PEST IN CALIFORNIA RICE FIELDS. will be treated with DPA herbicide. Calif. Dept. Agr. BuL 36(2) : 42-48. 'U.S. GOVERNMENT PRINTING OFFICE: 1966- ' 780-396