Seed Technology That Follow

IRRN GUIDELINES

The International Rice Research Guidelines for contributors environment (irrigated, rainfed Categories of research published Newsletter objective is: (revised) lowland, upland, deepwater, tidal "To expedite communication wetlands). GERMPLASM IMPROVEMENT among scientists concerned with The International Rice Research • Specify the type of rice culture genetic resources the development of improved Newsletter is a compilation of brief (transplanted, wet seeded, dry genetics technology for rice and for rice- reports of current research on topics seeded). breeding methods based cropping systems. This of interest to rice scientists all over • Specify seasons by characteristic yield potential publication will report what the world. Contributions should be weather (wet season, dry season, grain quality scientists are doing to increase the reports of recent work and work-in- monsoon) and by months. 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GERMPLASM IMPROVEMENT CROP AND RESOURCE MANAGEMENT

Genetic resources Soil microbiology 5 Sheath blight (ShB) resistance in wild rices 22 Influence of wild plant and crop residues on rice yield 5 Panicle and grain characters of some glaberrima cultivars in Sierra Leone 22 Effect of seeding rate on dry matter production and nitrogen accumulation of Sesbania rostrata Genetics

6 Inheritance of response to gibberellic acid (GA3) in semidwarf rices Physiology and plant nutrition 23 Effects of a growth regulator on rice seedling growth Breeding methods 7 A high-yielding early hybrid rice with multiple resistance Fertilizer management 7 Effect of gibberellic acid on pathogen infection in hybrid rice seed 23 Greenhouse evaluation of urea supergranules (USG) containing 8 Screening rices for good panicle exsertion diammonium phosphate (DM) for transplanted rice 24 Rate and time of N application for direct seeded irrigated rice Yield potential 25 Influence of modified urea and placement on N use in irrigated rice 8 Genetic studies on rice flag leaf weight and midrib and side vein thickness 25 Influence of modified urea materials at different N rates on estimated 9 Photoperiod sensitivity of traditional rice variety of Andamans wetland rice soil ammonium-N and nitrate-N 9 Association of rice ratooning ability and vigor with grain yield 26 Contribution of flood siltation to boro rice yield and response to N and K 10 Effect of leaf senescence and stubble carbohydrate content on ratoon 27 Response of rice to Azospirillum brasilense and organic manures on rice yield organic- and chemical-few farms in India 10 Effect of high humidity and low temperature on spikelet fertility in indica rice Crop management 28 Effect of traditional and improved nursery methods on seedling growth Pest resistance—diseases and rice yield 11 Some components of partial resistance to blast (B1) in indica rices 12 Analysis of rice blast (Bl) pathogen virulence in Egypt Integrated pest management—diseases 12 Resistance to blast (Bl) in Egyptian rice varieties 28 Nonfluorescent Pseudomonas strains causing rice sterility and grain 13 Changes in rice leaf pigment due to tungro (RTV) infection discoloration in Colombia 13 Development of kresek symptoms on some rice varieties 29 False smut incidence on rice relative to plant characters and environmental 14 Resistance of wild rices to bacterial blight (BB) factors 30 Bakanae and foot rot of rice in Punjab, Pakistan Pest resistance—insects 30 Efficacy of ethofenprox in preventing rice tungro (RTV) infection 14 Biology of rice leaffolders (LF) on susceptible IR36 and resistant TKM6 15 Rearing yellow stem borer (YSB) for screening varietal resistance Integrated pest management—insects 15 MDU3, a new gall midge-resistant rice 30 Mutual interference among wolf spider adult females 16 Using rice nurseries to collect thrips for use in screening rice germplasm 31 Fluctuation of yellow stem borer (YSB) populations in Raichur, Kamataka, India Pest resistance—other pests 31 Toxicity of insecticides to mirid bug predator of rice brown planthopper 16 Reaction of rice cultivar Faro 11 to sugarcane cyst nematode Heterodera 31 Feeding and food assimilation by two species of rice leaffolders (LF) on sacchari selected weed plants 32 Mass rearing of a mirid predator Stress tolerance—adverse temperature 17 Promising cold-tolerant and high-yielding rice lines for Ndop Plain, Integrated pest management—weeds Northwest Camemon 33 Weed control in dry and wet seeded irrigated rice 18 Performance of cold-tolerant varieties in western hills of Nepal 33 Effect of time and number of weedings on direct seeded upland rice yields 18 Screening rice for temperature tolerance in northern Nigeria 34 Weed composition in dry seeded wetland rice

Stress tolerance—adverse soils Farming systems 19 Phosphorus activity in genotypes with low phosphoms tolerance 34 Intercropping following rice 34 Rice-based cropping systems for rainfed lowland conditions Integrated germplasm improvement 35 Production potential and economics of upland rice + pigeonpea 20 IET6666, a new high-yielding rice variety for Assam 36 Rice-based intercropping systems for rainfed upland conditions of 20 Performance of IR46 and IR10781-143-2-3 under transplanted rainfed Chotanagpur plateau lowland conditions in Nepal 36 Some transplanted rice-based cropping systems 37 Water requirement for peanut following rice in Bangalore Seed technology 37 Rice variety to fit cropping patterns in Tripura, India 21 Using electrical conductivity to determine maturity stage for quality 37 Relay cropping in upland rice fallows rice seeds 21 Mid-storage correction to prolong viability of rice seeds

GERMPLASM IMPROVEMENT Genetic resources

Sheath blight (ShB) in existing rice cultivars. To identify R. solani in a rice hull and grain medium resistance in wild rices additional sources, we tested 76 wild rice (3:1 vol/vol) was placed between the accessions in IRRI’s ShB nursery. (Some tillers at the base of each plant 45 and A. D. Amante, R. de la Pena, L. A. Sitch, H. accessions were represented by more than 65 d after seeding. Disease reaction was Leung, and T. W. Mew, IRRI one source, giving a total of 106 entries.) scored 15-20 d after flowering and Seedlings were planted in two 50-cm relative lesion height (RLH = lesion Development of host resistance to ShB, rows at 5 hills/row, spaced 10 cm height [cm]/plant height [cm] × 100) caused by Rhizoctonia solani, has been between hills and 20 cm between rows. computed. hampered by limited sources of resistance Inoculum (a 10- to 14-d-old culture of Although all entries showed ShB symptoms on the leaf sheath, about Wild rices with resistance or moderate resistance to the ShB pathogen Rhizoctonia solani. IRRI, 1990. one-third (35 entries) were more resistant than susceptible check IR58 Species Plants Plant Lesion IRGC tested height height RLH a Grade b (see table). On the basis of RLH, O. accession no. (no.) (cm) (cm) minuta Acc. 101089 (RLH = 18.7%) and O. rufipogon Acc. 100907 (RLH = O. nivara 103422 3 127.8 39.4 30.2* 3 19.5%) were resistant; 34 other entries 103835 3 119.6 36.4 30.1 * 3 were moderately resistant. These 103 840 3 126.7 36.3 29.3 3 accessions may be useful donors of ShB 101971 1 130.1 38.6 29.3 3 104444 1 113.9 34.1 29.3 3 resistance for rice improvement. 104473 2 120.2 35.0 28.7* 3 101 193 1 100.7 26.6 27.4* 3 103841 3 114.0 31.4 27.3** 3 103841 1 122.1 33.6 27.2* 3 Panicle and grain characters 103824 1 91.2 25.2 26.8* 3 of some glaberrima cultivars 104705 1 108.0 28.9 26.5 3 101967 1 120.4 32.2 26.5 3 in Sierra Leone 101973 1 124.2 31.0 25.0* 3 100898 1 101.0 23.6 22.8** 3 M. S. Jusu and S. S. Monde Rice Research O. barthii Station, Rokupr, Sierra Leone 101827 3 88.0 26.0 29.5 3 104304a 2 92.1 23.8 25.3* 3 104304a 1 95.2 22.5 23.0* 3 A large number of subsistence farmers in 104304b 1 99.0 22.3 22.0** 3 Sierra Leone cultivate Oryza gluberrima 101317 3 98.6 22.0 21.7** 3 because of its wide adaptability to stress, O. perennis high weed competitiveness, and good 104765 2 172.3 34.8 30.0 3 eating qualities. 104822 2 109.8 31.8 28.3* 3 104796 2 115.3 32.4 27.8* 3 Evaluation of cultivars collected 100969 1 135.1 37.4 27.8* 3 during the last 3 yr indicates consider- 103848 1 106.5 29.4 27.6 3 able phenotypic variation. 100692 2 107.8 28.5 26.2* 3 104754 2 93.4 24.5 26.0* 3 We evaluated 60 O. glaberrima 104782 1 130.0 34.0 25.8* 3 varieties collected in Jan 1988 from 104766a 3 124.9 31.6 24.4** 3 upland fields in the Southern Province for 104642 2 86.2 19.3 23.4* 3 104822 1 104.4 24.4 23.0* 3 variations in morphological and agro- O. rufipogon nomic characters. 100907 1 120.8 26.8 21.5* 3 Panicle exsertion tended to be moder- 100907 2 154.7 31.0 19.5* 1 ate, panicle type open, and secondary O. latifolia branching rare (Table 1). Threshability 100966 1 127.8 30.6 23.5* 3 100964 1 122.0 33.0 26.5 3 was easy (this is a major defect in O. minuta glaberrimas). 101089 1 93.2 17.9 18.7** 1 Panicle length, grain length, and IR58 (susceptible check) 77.7 32.0 41.2 5 grain shape varied widely (Table 2). a * and ** = significantly different from susceptible check at 5% and 1 % level by LSD test. b 1 = resistant. 3 = moderately resistant, Panicles 25 cm and longer occurred in 5 = moderately susceptible. Accessions 5886 (Pa China), 5568 (Pa

IRRN 15:3 (June 1990) 5 Table 1. Panicle and grain characters of some Oryza glaberrima cultivars. Sierra Leone, 1988.

Panicle exsertion Panicle type Secondary branching Panicle threshability Seed coat color IRRI scale Description Accessions Description Accessions Description Accessions Description Accessions Description Accessions (%) (%) (%) (%) (%)

0 – – – Absent 95.0 – – – – 1 Well exserted 23.3 Compact 0.00 Light 5.0 Difficult 1.7 White 1.7 2 – – – Heavy 0.00 – – Light brown 3.3 3 Moderately 41.7 – – – – – Speckled 10.0 exserted brown 4 – – – – – – – Brown 71.6 5 Just exserted 35.0 Intermediate 15.0 – – Intermediate 1.7 Red 0.0 – – – – 6 – – – Variable 11.7 purple 7 Partially 0.0 – – – – Purple 1.7 exserted 9 Fully exserted 0.0 Open 85.0 – – Easy 96.6

Table 2. Distribution of some panicle and grain 23, and C2123 (with sd 1 gene) were 10 d after spraying. characters of some O. glaberrima Cultivars, Sierra sensitive to GA ; Xue-He-Ai-Zao and In five combinations, all F s were Leone, 1988. 3 1 Xue-4 (with sd s gene) were insensitive. sensitive to GA 3 (the F 1 of Xue-He-Ai- Accessions Evenly germinating seeds were sown Zao/Xue-4 was missing). The F 2s Character Range (%) in 50- × 20- × 15-cm plastic trays and segregated (Fig. 1). The genotypes of Panicle length 15-20 5 sprayed with 20 ppm GA 3 solution the Sd1 - Sd 8 - and sd1 sd 1Sd 8 - were sensitive; the (cm) 20-25 87 next day. Seedling height was measured genotypes of Sd1 - sd8 sd 8 and sd1 sd 1sd 8sd 8 25 & above 8 Dehulled grain length Medium (5.51 to 2 (mm) 6.60 mm) Long (6.60 to 38 7.50 mm) Extra long (more 60 than 7.50 mm) Grain length: width ratio Medium (2.1 to 3.0) 12 Slender (>3.0) 88

Kamara), 5620 (Pa D.C.), 5838 (Pa Keble), 5290 (Walei), and 5839 (Pa Temne). Accession 5886 (Pa China) also showed some secondary branching and low threshability. Genetics

Inheritance of response to gibberellic acid (GA 3) in semidwarf rices

Xu Jianlong and Shen Zongtan, Agronomy Department, Zhejiang Agricultural Univer- sity, Hangzhou; and Lin Yizi, Plant Institute, Zhejiang Academy of Agricultural Science, Hangzhou, China

Five semidwarf varieties (plant height about 65=90 cm), keng type, with sd 1 or sd s gene, were analyzed for heritability 1. Frequency distribution of responses of different crosses to GA . of response to GA 3, Cheng-Tu-232, Jia- 3

6 IRRN 15:3 (June 1990) Guizhou indigenous variety) have strong cold tolerance. Wei-you 481 performed well in 1988 regional trials for single, mid-season rice cropping areas 1,100-l,500 m altitude in Guizhou Province. Average yields were 8.4 t/ha, 9% higher than that of popular hybrid rice Wei-you 64 (Table 1). An outstanding characteristic of Wei- you 481 is its multiple resistances (Table 2). In artificial inoculation tests in 1988, it was resistant to 102 Pyricularia oryzae isolates belonging to 21 races.

Effect of gibberellic acid on 2. Response of generations of Cheng-Tu-232/Xue-He-Ai-Zao to GA 3 . P 1 = Cheng-Tu-232, P 2 = Xue-He-Ai-Zao, F 1 = P 1 /P 2 , DW= pathogen infection in hybrid dwarf. rice seed

were insensitive, at a 3:1 ratio (9 Sd 1 -Sd 8 - probably having both sd genes, were Zhou Zhongyue, Tang Shande, and Mo :3 sd 1 sd 1 Sd 8 :3 Sd 1 -sd 8 sd 8 :1 sd 1 sd 1 sd 1 sd 8). found in the F2 of every combination Zhijun, Lingling Agricultural School, Hunan, The F 2 of Xue-He-Ai-Zao/Xue-4 did not (Fig. 2). Response of the dwarfs was China segregate and was insensitive. similar to that of Xue-He-Ai-Zao. Dwarf plants (height less than 40 cm), Hybrid rice seed may be infected with glume spots caused by pathogens, primarily Alternaria, and kernel smut Breeding methods caused by Tilletia barclayana. Serious infection results in low seed viability. A high-yielding early hybrid Qian-hui 481 is an isocytoplasmic R-line We studied the effect of six levels of rice with multiple resistance derived from Zhen Xian 97A/Tai Yin 1// gibberellic acid (GA3) spray on incidence Xiankengnuo///Gui 6/IR26////IR24/ of glume spots and kernel smut on Zheng Lingxiang and Tang Hongjing, Institute Liuganjianye (an indica/japonica combi- hybrid seed produced on CMS line of Rice, Guizhou Academy of Agricultural nation). Indica varieties Tai Yin 1 and V20A. The experiment was laid out in a Sciences, Guiyang, China IR26 have bacterial blight (BB) resis- randomized complete block design with tance and IR24 and IR26 have blast (B1) three replications. Both glume spots and Wei-you 481 is a newly released early resistance in Guizhou. Japonica varieties kernel smut incidence decreased with indica hybrid of V20A/Qian-hui 481. Liuganjianye and Xiankengnuo (a GA 3 application (see table). Application

a Table 1. Some agronomic characteristics of Wei-you 481, Guizhou, China. Effect of GA 3 application on pathogen infection of hybrid rice seeds. a Hunan, China, 1988. Duration Plant Panicles Grains 1,000- Seed Yield Yield/d 2 Variety (d) ht (no./m ) (no./ grain set (t/ha) (kg/ha) GA 3 level Glume spot Kernel smut (cm) panicle) wt (g) (%) (g/ha) (%) (%)

Wei-you 481 162 88.5 342.0 118.2 27.0 78.2 8.4 52.2 0 44.0 d 22.1 b Wei-you 64 153 76.7 394.5 108.5 28.4 77.5 7.7 51.1 90 25.0 b 6.0 a

a 180 23.9 a 7.7 a Mean of 4 rites (1100-1500 m above sea level) in the regional trials of hybrid rice in Guizhou Province, 1987. 240 23.4 a 3.9 a 360 26.5 c 6.8 a 450 27.6 c 4.8 a Table 2. Reaction a of Wel-you 481 to B1, BB, and cold, Guizhou, China, 1987. a In a column, mean followed by difficult letters are significantly different at the 5% level (DMRT). Reaction to B1 Reaction Reaction to cold Variety to Leaf B1 Neck B1 BB Seedling stage Flowering stage b level did not show significant differences Wei-you 481 2.0 1.5 3.0 3.0 ++ in kernel smut incidence, but glume spots wei-you 64 4.5 5.0 7.0 7.0 + decreased up to 240 g GA3/ha. Higher a Mean of 4 test sites in Guizhou Province. Scoring according to Standard evaluation system for rice scale: 0-9. b + = moderate cold application increased glume spot inci- resistance, ++ = strong cold resistance. dence.

IRRN 15:3 (June 1990) 7 Screening rices for good randomly at the end of 50% flowering. panicle exsertion Panicle exsertion was measured as the Yield potential distance between the place of emergence S. Jebaraj, S. Palanisamy, and M. Subrama- of the flag leaf to the base of the panicle. Genetic studies on rice flag nian, Agricultural Botany Department, The varieties studied showed highly leaf weight and midrib and Agricultural College and Research Institute, significant differences in panicle exser- side vein thickness Madurai 625104, Tamil Nadu, India tion. Exserted panicle length varied from 1.60 to 10.95 cm, with a 40% coefficient Shen Fu-Cheng and Liu Chuang-Xiu, Guizhou We evaluated panicle exsertion in 40 of variation (see table). T414, 864, 916, Academy of Agricultural Sciences, Guizhou genotypes, including 4 commonly 979, 1037, 2253, 2256, 2292, 2699, 2710, Province, China cultivated medium-duration rice varieties, 2730, and 2869 had significantly better during 1987 wet season (Jun-Sep). The exsertion. Thicker rice leaves have been found to experiment was laid out in a randomized These types could be used to develop have higher photosynthetic rates. Some block design with two replications. male-sterile lines with well-exserted studies have related photosynthetic Three plants/replication were selected panicles for hybrid seed production. rate to the diameter of the leaf vascular bundles. We studied the heritability of specific Panicle exsertion in different rice varieties. a Tamil Nadu, India, 1987 wet season. flag leaf weight (SLW), midrib thickness Mean (TMR), and side vein thickness (TSV) at Type Variety Origin exsertion heading in parental and F 2 populations of length (cm) Guichao 2/82-856 and Conggui 226/82- 856. Vein thickness was measured by T23 Safeda Central province 6.33 T414 Long grain, awned Madurai 7.76 micrometer. Flag leaf area (A) was mea- T864 Kesse-Koyoba (m) West Africa (Gambia) 9.75 sured as T916 V. Melonoceros Kore Russia 6.90 T951 Matali Punjab 2.18 A = 2/3L 1 L 2 +1/3L 3 (L 1 -L 4 ) T979 Ichabtsi China 9.27 T1004 Sauchaotsi China 6.14 where L 1 = leaf length, L 2 = leaf greatest T1037 III 14-8 China 9.78 width, L 3 = leaf basal width, and L 4 = leaf T1403 Thavalaikannan Malabar 4.01 T1418 Gudumaskathi S. Canara 6.33 length from the widest part to the pointed T1621 Dc. Sierrikone Africa 5.92 end. T1651 Madaoliso Brazil 1.71 Variety 82-856 had very thick leaves T1745 Senkar Udumalpet 5.83 2 T2253 Lati Amtoo Mohar (157) Bombay 7.15 (SLW = 10.027 mg/dm , TMR = 78.07 T2256 Banaspatri (Medium) Lashkar (Gwalior) 10.95 mm, TSV = 38.51 mm). Guichao 2 and T2292 Kalomashine Kalitong, Assam 10.55 Conggui 226 had thinner leaves (for T2337 Nira USA 3.65 2 T2402 CP15 CRRI, Cuttack 6.60 Guichao 2, SLW = 6.03 mg/dm . TMR = T2408 Cuttack 10 Aikoku CRRI, Cuttack 4.94 41.47 mm, TSV = 23.80 mm; for T2436 China 62 China 5.52 Conggui 226, SLW = 6.227 mg/dm2, T2613 Chungnung No. 4 China 5.71 T2669 Varylava Ali Combo Madagascar 6.16 TMR = 45.70 mm, TSV = 23.89 mm). T2684 Tainan 1 Japonica - Taiwan 5.51 Leaf heritability ( h2 ) was calculated T2688 Kaohsiung 64 Japonica - Taiwan 5.18 as T2690 Irradiated Taichung 65 Japonica - Taiwan 5.23 T2699 (CP231/3 *Bluebonnet)/PI215936 - 9.50 WF 2 -1/2(VP 1 +VP 2 ) 2 T2706 PI 215936/CI 9214 - 6.11 h = × 100 T2710 PI 215936/CI 9214 - 9.50 VF 2 T2717 CI 9402 (CP23 1/Bluebonnet) - 5.71 T2721 (PI 215936/CI9214) - 4.78 All F 1 values for TMR, TSV, and T2729 CI 9155/(C.50/Kh.27) - 4.08 SLW in both combinations were T2730 Hsinchu 50 Taiwan 10.11 between the two parents (see figure). T2811 Cuttack 45 (Ch.45/AC 1951) Cuttack 4.43 T2842 14 E. Punjab 2.54 The F 2 distributions for SLW and TSV T2845 1206-17-21 Maharashtra 4.46 were continuous and almost abnormal in T2869 Takao Taiwan 7.00 both combinations. Distributions for - IR20 Philippines 4.18 - Ponni Malaysia 5.98 TMR were skewed, showing predomi- - Co 43 Coimbatore 1.60 nance of the lower segregants, in both - Co 44 Coimbatore 2.94 combinations. Heritabilities were Overall mean 6.05 SLW>TMR>TSV. For Conggui 226/82- LSD 0.83 856, heritabilities were 78.63% for SLW CV = 40.3 1 % 62.06% for TMR, and 27.10% for TSV. a Underlined values a significantly better than overall mean. F test significant at 1 % level. For Guichao 2/82-856, heritabilities were

8 IRRN 15:3 (June 1990) 2. Variation in daylength and temperature during different months in Port Blair, India.

of CR1009 was about 65 d and that of C14-8 80 d. The photoperiod-sensitive F 2 distribution of TMR, TSV, and SLW in the cross of Guichao 2/82-856F 2 . phase was about 30 and 226 d, respectively. 72.52% for SLW, 66.19% for TMR, and TMR was controlled by some major The marked difference in flowering 33.84% for TSV. genes and a small number of dominant durations with month of sowing is This suggests that SLW and TSV had genes with cumulative and unequal attributed mainly to response to varying multigenic and additive actions and that effect. daylengths in different months (Fig. 2). Variation in days to flowering was caused by difference in vegetative lag Photoperiod sensitivity of with the moderate photoperiod sensitivity phase only. The basic vegetative, traditional rice variety of of modern variety CR1009 at 12° N lat. reproductive, and ripening phases were Andamans and 92-94° E long. The crops were sown constant in both varieties. on the 10th d of each month for 1 yr. C14-8 is highly sensitive to slight S. Singh and T. Ram, Central Agricultural CR1009 sown in Oct flowered in variations in daylength, indicating strong Research Institute, Port Blair 744101, India 100 d. When sown in Mar and Apr, it photoperiod sensitivity. flowered in 130 d (Fig. 1). C14-8 sown in Local rice variety C14-8 occupies more Nov flowered in 115 d. When sown in than 50% of the rice area in Andamans. Dec, it flowered in 341 d, the difference Association of rice ratooning We compared its photoperiod sensitivity being 226 d. The basic vegetative phase ability and vigor with grain yield

M. Subramanian and A. Ramalingam, Agricultural Botany Department, Agricultural College and Research Institute (ACRI), Madurai, Tamil Nadu, India

We evaluated rice ratooning ability, vigor, and yield in 22 rice cultivars during 1987 wet season. The trial was laid out in a randomized block design with three replications. At harvest, the main crop was cut leaving a 15 cm culm. The stubble was irrigated 3 d after harvest and 40 kg N/ha applied 7 d after harvest. Ratoon vigor was assessed as 1 = extra vigorous, 5 = intermediate or normal, 9 = very weak. A ratoon rating (RR) was calculated as av number RR = (1 - [0.1 ratoon vigor]) × of ratoon 1. Days to flowering of rice varieties sown in different months. tillers/plant

IRRN 15:3 (June 1990) 9 Relationship of carbohydrate content in stubble and leaf senescence at harvest to ratoon yield.a Madurai, India 1988.

Carbohydrate Leaf Ratoon yield Parent, cross content of senescence (g/10 stubble (%) (%) plants)

Bhavani 20.5 55.2 14.4 MDU3 17.8 51.4 12.3 IET6262 21.2 57.6 12.8 IET6709 23.2 52.9 13.6 IET7552 18.8 60.8 15.1 IET9239 24.2 59.6 11.7 Bhavani/MDU3 18.6 (18.2) 54.0 (53.4) 14.5 (12.5) Bhavani/IET6262 21.2 (19.4) 54.9 (54.2) 16.1 (13.2) Bhavani/IET6729 20.7 (19.7) 51.2 (58.0) 15.4 (15.1) Bhavani/IET7552 19.7 (20.9) 66.3 (58.7) 14.9 (16.3) Relationship between ratoon rating and ratoon Bhavani/IET9239 20.6 (22.0) 55.0 (58.2) 14.3 (12.8) MDU3/IET6262 17.6 (16.7) 52.0 (56.3) 12.8 (13.5) grain yield in 22 rice cultivars. ACRI, Tamil MDU3/IET6709 20.2 (21.5) 51.4 (50.4) 13.1 (13.7) Nadu, India, 1987 wet season. MDU3/IET7552 17.8 (16.7) 5 1.7 (56.0) 12.4 (15.0) MDU3/IET9239 19.4 (21.2) 56.8 (66.3) 12.5 (1 1.9) The association between RR and IET6262IET6709 22.0 (23.8) 58.4 (56.2) 14.4 (15.2) ratoon yield was positive and significant IET6262/IET7552 17.5 (19.0) 62.2 (60.1) 13.0 (15.1) IET6262/IET9239 21.7 (25.2) 52.9 (58.5) 12.8 (12.5) (see figure). Most cultivars with high RR IET6709/IET7552 20.7 (22.3) 56.5 (55.2) 15.2 (16.8) had high ratoon yield. RR can be used as IET6709/IET9239 24.8 (23.8) 52.5 (54.9) 13.5 (12.6) a criterion in selecting rice cultivars for IET7552/IET9239 22.6 (20.2) 62.5 (56.5) 15.9 (120) Mean: Parent 20.95 56.26 13.32 high ratooning ability. cross 20.52 55.71 13.96 SE 0.43 0.94 0.28 LSD (P = 0.05) 1.22 2.65 0.78 Effect of leaf senescence and ns ns stubble carbohydrate content Correlation with ratoon yield 0.0137 0.2136 on ratoon rice yield a Figures in parentheses are for reciprocal cross. S. Arumugachamy, P. Vivekanandan, and M. Subramanian, Agricultural Botany Depart- IET7552 and Bhavani had the highest were not significant, indicating low ment, Agricultural College and Research ratoon yields (see table). The effects of influence of these factors on ratoon yield. Institute, Madurai, Tamil Nadu, India carbohydrate content of the stubble and This emphasizes the importance of leaf senescence at harvest on ratoon yield inherent ratooning ability of parents. We studied the relationship between carbohydrate content in the stubble and leaf senescence at main harvest and ratoon Effect of high humidity and yield in rice genotypes Bhavani, MDU3, low temperature on spikelet IET6262, IET6709, IET7552, and fertility in indica rice IET9235 and their crosses during Oct 1988. Shi Chunhai and Shen Zongtan, Agronomy Each entry was planted in two 2-m- Department, Zhejiang Agricultural Univer- long rows at 20- × 10-cm spacing, in a sity, Hangzhou, China randomized block design with three replications. Recommended practices were Rains, high humidity, and low tempera- followed for both main and ratoon crops. ture lower spikelet fertility in first crop Ten randomly selected plants of each indica rice and could increase percent- parent and cross from each replication age of empty spikelets and reduce yields. were used to estimate main crop stubble We studied the effect of such wet weather carbohydrate content, leaf senescence, on 12 indica varieties in 1989. and ratoon yield. Spikelet fertility percentage (SFP) was Total carbohydrate content was estima- measured on 6-10 randomly selected ted by phenol sulfuric acid method. Leaf panicles at heading. SFP was reduced senescence was estimated by with increased humidity and decreased Total number senescent temperature (see figure). The most % senescent leaves important meteorological factor was Response of 3 groups of indica varieties to = × 100 leaves Total number green leaves relative humidity ( r = -0.96*), followed relative humidity and daily mean temperature at at milk stage by mean temperature 3 d after heading. heading and flowering. Hangzhou, China, 1989.

10 IRRN 15:3 (June 1990) Spikelet fertility percentage in indica varieties grown under different weather conditions. Hangzhou, from 5 DAI to when a lesion stopped China, 1989. sporulating), and difference in infectivity SFP at given heading date (DIE, percent infected plants 7 DAI) were Degree of measured. Plants were observed every 2 h a b Variety Normal reduction Group beginning 70 h after inoculation. One leaf weather Wet weather (%) lesion on each of 10 seedlings per variety 26 Jun 30 Jun 4 Jul 8 Jul Mean was selected and its area measured The leaf with lesion was placed in a glass tube 88-7212 83.0 66.4 45.0 33.0 48.1 42.0 Susceptible 89-9382 64.9 38.5 45.7 29.7 38.0 41.5 Susceptible containing 1 ml distilled water mixed with 89-9383 81.7 61.5 41.6 58.9 54.0 33.9 Susceptible mercury bichloride, and left for 15 h. 50.4 59.8 31.3 Susceptible Cong-xie 39 87.1 74.1 54.8 Conidia samples were taken at 0800 h Er-jiu-feng 87.4 66.8 65.5 56.4 62.9 28.0 Middle HG8547 81.7 60.8 57.0 63.5 60.4 26.0 Middle each day. Each glass tube was shaken Zhen-yu 29 74.0 61.3 59.1 46.3 55.6 24.9 Middle vigorously to dislodge conidia and taken 55.2 71.2 61.2 22.7 Middle Ai-gan-shan-li-qi 79.2 57.2 to the laboratory for counting. Conidia per Zhe-fu 802 85.8 75.6 55.3 70.1 67.0 21.9 Middle Fu-lian-ai 83.6 65.3 69.2 66.6 67.0 19.8 Tolerant lesion and per cm lesion area were calcu- 6713 88.2 80.6 67.3 64.9 70.9 19.6 Tolerant lated. Tubes with fresh solution were ins- 68.2 Tolerant Guang-lu-ai 4 78.2 64.2 74.6 66.0 12.8 talled on the same lesions by 1700 h daily Meanc 81.2 a 64.2 b 57.7 bc 56.4 c 59.4 bc 27.0 until sporulation ceased. Maximum value - minimum value The partially resistant cultivars had a Degree of reduction (%) = × 100. Maximum value slightly longer IP than susceptible check b SFP degree of reduction for tolerant, intermediate, and susceptible varieties was <20, 20-30, and >30, respectively. c Means Yuan-Feng-Zao (see table). RIE on Xiang- followed by the same letter are not significantly different at the 5% level. Zhou No. 5, Zhe-Fu 802, and Er-Jiu-Feng were significantly less than on the suscep- Among varieties, SFP differed during weather. Guang-lu-ai 4, 6713, and Fulian- tible check. With isolate ZC15, RIE of all normal weather and wet weather (see ai had higher SFP in wet weather than 88- test varieties was lower, indicating it is a table). The varieties could be divided into 7212 and 89-9382. less aggressive isolate. LS was signifi- three groups according to response to wet cantly smaller on all partially resistant cultivars than on the susceptible check. SC on all test varieties was lower than Pest resistance—diseases that from the susceptible check. SC on Zhu-Ke No. 2 was the lowest for both relative infection efficiency (RE, no. of isolates. Some components of partial lesions/plant 7 d after inoculation [DAI]), DIE of Xiang-Zhou No. 5, Er-Jiu-Feng, resistance to blast (BI) in lesion size (LS, length and width of 20 and Zhu-Fu 802 were significantly lower indica rices randomly selected lesions from each than that of Zhu-Ke No. 2 and the suscep- replication, estimated in mm 2 [lesion tible check, and were much lower with Sun Guochang, Shi De, Zhuge Gen-zhang, length × width × 0.5]), sporulation capa- isolate ZC15 (no infection on Xiang-Zhou and Sun Shuyuan, Plant Protection Research city (SC, total no. of conidia produced No. 5). This indicates that isolate ZC15 Institute, Zhejiang Academy of Agricultural Sciences, China The components of partial resistance of 5 rice varieties inoculated with isolates of P. oryzae. a Hangzhou, China, 1989. Indica rice varieties Xiang-Zhou No. 5, Er-Jiu-Feng, Zhu-Ke No. 2, and Zhe-Fu SC c b 802 have shown relatively long-lasting Variety RIE LS IF DIE (lesions/plant) (mm 2 ) Per lesion Per cm 2 lesion (h) resistance to Bl ( Pyricularia oryzae ) in (%) farmers’ fields. In 1989, we evaluated Race ZBIS (0262) some components of partial resistance, Xiang-Zhou No. 5 1.53 c 1.13 c 2,983 b 99,667 bc 79.2 a 46.9 b Er-Jiu-Feng 2.36 bc 1.80 c 2,850 b 124,000 bc 73.2 c 47.1 b with Yuan-Feng-Zao as the susceptible Zhu-Ke No. 2 3.78 ab 2.08 b 2,038 b 70,667 c 75.9 b 81.4 a check. Zhe-Fu 802 2.32 c 1.84 b 4,133 a 155,500 ab 73.0 c 51.1 b Seedlings selected for uniform growth Yuan-Feng-Zao 4.20 a 3.34 a 4,160 a 192,200 a 71.0 d 95.1 a were spray-inoculated with two pathogen Race ZC15 (84-76) isolates (10 5 conidia/ml at 20 d after Xiang-Zhou No. 5 0.00 ------sowing). The experiment was laid out in Er-Jiu-Feng 1.71 ab 1.54 b 5,267 a 123,000 bc 74.0 bc 26.5 c Zhu-Ke No. 2 1.94 ab 1.49 b 2,850 b 65,667 c 83.3 a 45.1 b a randomized complete block design with Zhe-Fu 802 1.44 b 0.71 b 3,000 b 146,167 ab 77.5 b 16.9 c three replications of 20 seedlings each. Yuan-Feng-Zao 2.21 a 4.12 a 5,830 a 217,800 a 71.6 c 84.8 a Incubation period (IP, time from ino- a In each column, variety means followed by a common later are not significantly different by DMRT at P = 0.05. b Data from culation to first appearance of lesions), 7 DAI. c Mean number of conidia from samples taken 5, 7, 10, and 12 DAI.

IRRN 15:3 (June 1990) 11 was less aggressive, and that Xiang-Zhou suspension (about 50,000/ml). Inoculated Table 1. Reaction of selected rice genotypes to 2 No. 5 may have specific resistance genes plants were left in a moist chamber for 48 representative Pyricularia oryzae isolates of Egypt. effective against ZC15. h, then transferred to the greenhouse. Reaction to P. oryzae The cultivars that have shown durable Disease was scored 10-15 d later. Cultivar isolates resistance in the field have partial resis- B1 virulence on local cultivars Giza ID13 a IG1 b tance to the races tested in this study. 159, Giza 171, Giza 172, and Reiho was 100% both years (see table). Virulence IRRI was zero on indica cultivars IR28, IR50, IR20 1 1 Analysis of rice blast (BI) IR22 1 1 pathogen virulence in Egypt and Giza 181, and rare on Giza 175. IR24 1 2 Currently popular breeding line GZ2175- IR28 1 1 5-6 was affected by 20% of the isolates in IR36 1 1 A. P. K. Reddy, IRRI-Egypt Project, RRTC IR50 1 1 Sakha, Kafr el Sheikh, Egypt 1988 and 53% in 1989 (see table). IR52 1 1 This increase in virulence on GZ2175- IR60 1 1 5-6 is associated with an increase in area IR62 1 1 We evaluated the virulence of Pyricularia IR64 1 1 oryzae in B1-affected areas of the Nile sown to this line, from 1,000 ha in 1988 IR66 1 1 to 10,000 ha in 1989. IR2003-P18-16 1 1 Delta (governorates of Beheira, Dakhalia, IR2153-338-3 1 1 Damietta, Gharbia, and Kafr el Sheikh) IR19743-46-1 1 1 1988-89 summer seasons. Resistance to blast (BI) in IR25571-31-1 1 1 Rice leaves and panicles with typical Thailand Egyptian rice varieties RD7 1 1 B1 lesions were collected from farmers’ RD9 1 1 fields. Single lesions were placed in petri A. P. K. Reddy and A. O. Bastawisi, Rice RD10 1 1 dishes with wet filter paper and incubated Research and Training Centre, Sakha, Egypt RD2l 1 1 RD25 1 1 at 25ºC until sporulation. S. Korea A group of conidia was aseptically B1 is a major production constraint in Iri 370 1 1 transferred with a pointed capillary tube Egypt. Resistance in a series of japonica Milyang 23 2 1 to rice leaf agar. For the purpose of this varieties released in 1954-84 was short. A Milyang24 2 1 Milyang 80 2 1 study, mass cultures from single lesions few indica breeding lines (IR28, IR1626- Milyang 85 2 1 were considered equivalent to single 203 [Giza 181]) released in recent years Suweon 346 1 1 conidial isolates. (Previous studies under retain resistance, but they have limited Japan BL 1 1 1 the same test conditions had indicated that commercial acceptability and narrow Kanto 1 1 2 single conidial cultures derived from genetic bases. Tsuyuake 1 3 single lesions are of one race.) We evaluated 500 improved cultivars, Toride 1 1 1 In 1988, 10 commercial cultivars and 8 breeding lines, and germplasm of diverse India Bala 1 1 international differentials were tested origin against the prevailing B1 pathogen Basmati 370 1 1 against 35 isolates. In 1989, 8 commercial races ID13 and IGl in the Nile Delta. Cauvery 1 1 cultivars and international differentials Entries grown in the greenhouse were CO 43 1 1 Padma 2 4 were tested against 52 isolates. inoculated with two representative Ratna 1 1 Test plants grown in 40- × 20- × 10-cm isolates of Pyricularia oryzae 15 d after Rasi 1 1 plastic boxes in 10-cm rows, 5 cm apart sowing (DAS). Temperature was main- Tella hamsa 1 1 USA were inoculated with aqueous spore tained at 21-32°C and relative humidity at Mars 1 1 >90% for 9-11 h. Cultivars found to be Lemont 1 1 P. oryzae isolates virulent to commercial rice cul- resistant 45 DAS are listed in Table 1. Mercury 1 1 tivars in Egypt 1988 and 1989. Noritai 1 1 Fifteen varieties were evaluated Egypt Virulence a (%) against three representative virulent Agami 3 4 Cultivar isolates from the rice-growing delta. Giza 175 2 1 1988 (n=35) 1989 (n=52) Entries planted in single rows in nursery Giza 181 1 1 Giza2175-5-6 8 2 Giza 159 100 100 boxes were inoculated at 15 DAS with Yabani 15 7 8 Giza 171 100 100 virulent isolates originating from (susceptible) Giza 172 100 100 Giza 159 (susceptible) 8 8 Reiho 100 100 Dakhalia. Kafr el Sheikh, and Gharbia Giza 172 (susceptible) 8 8 Giza 175 3 b 2 a governorates. After 48 h in the humid Reiho (susceptible) 8 8 Giza 181 0 0 chamber, they were transferred to glass- GZ1368-5-4 0 nt a Isolate from Sidisalem, on Giza on 2175-5-6. b Isolate from GZ2175-5-6 20 53 house benches. Disease was recorded 15 d RRTC research farm Sakha, on Giza 172. IR28 0 0 later. IR50 0 nt All tested IRRI varieties were resistant a (n) = number isolates tested. nt = not tested. b Intermediate to the local B1 pathogen races (Table 2). Cauvery) have a history of susceptibility reaction. Some of the varieties (IR50, Ratna, in the tropics. IR36, Rasi, and a few

12 IRRN 15:3 (June 1990) Table 2. Reaction pattern of 15 rice varieties to 3 Pyricularia oryzae isolates in Egypt. A slight increase in carotene and xanthophyll content was found in Reaction to isolate Reaction Variety Mean diseased leaves. Po 361 a Po 359 Po GMI Egypt Phil/India

Indica Development of kresek Cauvery 2.0 1.0 1.0 1.3 R S symptoms on some rice Ratna 1.0 1.0 1.0 1.0 R S IR50 1.0 1.0 1.0 1.0 R S varieties IR36 1.0 1.0 1.0 1.0 R MR IR28 1.0 1.0 1.0 1.0 R MS Y. Suryadi, Plant Pathology Department, Giza 181 1.0 1.0 1.0 1.0 R S Sukamandi Research Institute for Food Crops, Rasi 1.0 1.0 1.0 1.0 R R Japonica Subang 41256, West Java, Indonesia Gz 159 8.0 9.0 9.0 8.6 S S Gz 171 6.5 9.0 9.0 8.2 S S Xanthomonas campestris pv. oryzae Gz 172 8.0 9.0 9.0 8.6 S S Reiho 7.5 9.0 9.0 8.5 S S (Xco) can cause kresek symptoms on rice Shin 2 5.5 6.5 6.0 6.0 MS S seedlings. Great variations have been Aichi Asahi 8.0 9.0 9.0 8.6 S S found among strains of Xco in terms of Kanto 51 1.0 2.0 1.0 1.3 R S Toride 1 1.0 1.5 1.0 1.1 R R their pathogenicity in the rice plant. Mean 3.5 4.1 4.0 We induced kresek in the screenhouse CV (1) 7.1 Subplot LSD (0.05) = .27 using different strains of Xco on seven CV (2) 6.0 (Varieties) (0.01) = .36 rice varieties. The experiment was laid LSD Main plot at 0.05 Isolates at 0.01 out in a split-plot design with two replica- Interaction LSD at 0.05 = 0.47 tions, with rice varieties Pelita 1-1, Java 0.01 = 0.64 14, Gemar, Cisadane, Citanduy, TNl, and a Average value of 2 replications. Po 361 from Kafr El-Sheikh governorate, Po 359 from Dakhalia governorate. Po GMI from IR54 in the main plots and three isolates Gharbia governorate or strains of Xco in the subplots. Roots of 21-d-old seedlings were others that have shown more durable ments appear to be better donors of B1 washed, dip-inoculated for 15 min with resistance in other rice-growing environ- resistance in Egypt. 48-h-old bacterial suspension (±10 9 cfu/ ml), and seedlings transplanted in a wooden seedling box. Disease incidence Changes in rice leaf pigment releasing three viruliferous Nephotettix was recorded 14 d after inoculation. due to tungro (RTV) infection virescens (Dist.) per seedling. Infected Symptom development varied (see leaves were graded as 1/3 orange yellow, table). Cisadane had the least disease B. Srinivasulu and R. Jeyarajan,Plant 2/3 orange yellow, or completely orange symptoms with all three Xco strains, Pathology Department, Tamil Nadu Agricul- yellow. Chlorophyll content was extracted followed by Java 14, Pelita 1-1, and tural University, Coimbatore, India and estimated in 80% acetone. Carotene Gemar. Mean infection ranged from 9.7 and xanthophyll were extracted with 95% to 44.3%. Chlorosis and orange yellow color in ethanol and 85% methanol, respectively, leaves are characteristic symptoms of and estimated colorimetrically. Development of kresek symptoms on 7 rice varie- RTV disease in rice. We investigated the Chlorophyll content of diseased leaves ties Sukamandi, Indonesia, 1988. effect of RTV infection on green pigment was reduced in proportion to the length of Wilted plant a (%) (chlorophyll), orange pigment (carotene), orange-yellow color on a leaf (see table). Variety and yellow pigment (xanthophyll) at In leaves that had turned completely Si 8502 Si 8401 Si 8519 Mean different stages of pathogenesis. orange yellow, chlorophyll a, chlorophyll Gemar 16.55 12.68 17.83 15.67 ab Fifteen-day-old seedlings of suscep- b , and total chlorophyll were reduced by Cisadane 9.26 11.93 7.97 9.72 a tible TN1 were inoculated with RTV by 90, 94, and 91%, respectively. Citanduy 26.75 21.65 20.72 23.04 bc Pelita 1-1 14.56 19.94 11.95 15.48 ab IR54 36.99 33.85 22.62 31.15 c Effect of RTV on pigment of rice leaves. Coimbatore, India. Java 14 14.31 16.06 16.05 15.47 ab TN1 51.09 48.74 32.94 44.26 d Leaf color Chlorophyll a Chlorophyll b Total Carotene Xanthophyll Mean 24.21 a 23.55 a 18.58 b - chlorophyll CV variety (%) = 33.28 Completely orange yellow 0.234 0.078 0.312 ND* ND CV isolates (%) = 17.73 2/3 orange yellow 0.564 0.119 0.689 0.005 0.003 1/3 orange yellow 1.380 0.680 2.184 ND ND a Isolates Si 85012, Si 8401,and Si 8519 represented Indonesia Healthy 2.300 1.370 3.672 0.003 0.002 bacterium groups III, V, and VI, respectively. Means followed LSD (P = 0.05) 0.26 0.110 0.190 by the same letter do not differ significantly by DMRT (P = 0.05). a ND = not determined

IRRN 15:3 (June 1990) 13 Resistance of wild rices to Table 1. Best resistance to 6 BB races found in 198 accessions of wild species. IRRI, Feb-May 1989. bacterial blight (BB) IRGC Lesion length (cm) Species accession Origin R. Ikeda and G. A. Busto, Jr., Plant Breeding no. 1 2 3 4 5 6 Department, IRRI; and T. Ogawa, National O. rufipogon 104647 Thailand 1 1 1 1 1 Agriculture Research Center, Tsukuba, Ibaraki 1 O. rufipogon 104829 Thailand 1 1 1 1 1 305, Japan 1 O. rufipogon 104830 Thailand 1 1 1 1 1 1 O. rufipogon 104851 Thailand 1 1 1 1 1 2 We evaluated 198 wild rice accessions-10 O. nivara 104705 India 1 1 1 1 1 2 wild species and 22 natural hybrids O. officinalis 105081 Myanmar 1 1 1 1 1 2 against six races of BB caused by O. officinalis 105120 Philippines 1 1 1 1 1 1 Xanthomonas campestris pv. oryzae Feb- O. officinalis 105121 Philippines 1 1 1 1 1 2 May 1989 in the screenhouse at IRRI. O. officinalis 105174 Malaysia 1 1 2 1 1 1 Reactions to the BB races were tested O. eichingeri 105160 Uganda 1 1 1 1 2 1 using the clipping method. Five seedlings/ pot per accession were inoculated at booting to heading stages. Lesion length Table 2. Distribution of BB resistance genes in 198 accessions of wild species. IRRI, Feb-May 1989. was measured 18 d after inoculation, re- Accessions Occurrence (no.) of suspected gene sistance was lesion length less than 10 Genome Species tested cm, susceptibility was lesion length longer (no.) RRRRRR a Xa-3 xa-5 Xa-10 Xa-14 than 20 cm. AA O. rufipogon 98 66 9 More than half the tested accessions O. nivara 20 4 2 1 2 1 showed resistance to all six races Natural hybrids 22 8 2 3 (Table l). (Only a few cases of resistance Ag A g O. barthii 2 to all six races in the Philippines are A1 A 1 O. longistaminata 2 1 known in O. sativa varieties.) Ag1 A g1 O. glumaepatula 1 Based on patterns of reaction to the six CC O. officinalis 32 16 3 8 O. rhizomatis 4 3 1 races in each accession, 18 are suspected O. eichingeri 3 3 to have the Xa-3 gene, 11 the xa-5 gene, 2 CCDD O. latifolia 11 5 2 the Xa-10 gene, and 4 the Xa-14 gene O. grandiglumis 3 1 (Table 2). The Xa-4 gene, one of most po- a RRRRRR indicates resistance reactions to six Philippine races of BB. pular resistance genes in O. sativa varieties of tropical Asia, was not found. Pest resistance–insects

Biology of rice leaffolders (LF) on susceptible IR36 and Pupae were incubated and the first 20 significantly higher than on resistant resistant TKM6 pairs of moths emerging from each host TKM6 (see table). In the first 20 pairs of were kept in cages for mating. Adult moths emerging from the hosts, adult M. L. P. Abenes and Z. R. Khan, ICIPE-IRRI longevity of males and females was longevity on TKM6 was not significantly Project, IRRI observed separately. Fecundity was different from that on IR36. On the measured as number of eggs laid by each average, female moths laid the same IR36 is normally used as the suscep- female. number of eggs. In a follow up study, tible check and TKM6 as the resistant Larval survival, growth index, and adult LF emergence was 55% on IR36 check for rice LF Cnaphalocrocis pupal weight on susceptible IR36 were and 31% on TKM6. medinalis (Guenée). We reared 200 LF from the first-instar larval stage to Biology of C. medinalis raised on susceptible IR36 and resistant TKM6. a pupation in individual cages, on 30- to 35-d-old IR36 and TKM6 plants under Larvae Growth Growth Pupal Adult longevity (d) Fecundity standard greenhouse conditions. Variety becoming period index weight (eggs/female) pupae (%) (d) (mg) Female Male Larvae that pupated were weighed individually. A growth index was IR36 93 18.2 5.1 21.4 7.5 8.2 86.6 calculated as the percentage of larvae TKM6 81 19.1 4.2 17.9 9.0 8.6 99.6 Diff. 12** -0.9** 0.9** 3.5** -1.5 ns 4.4 ns -12.8 ns pupating divided by the average larval period on each host. *ns = not significant; ** = significant at P < 0.01 level by t test.

14 IRRN 15:3 (June 1990) Rearing yellow stem borer highly desirable. We developed a proce- At 25-30 d after infestation (DI), when (YSB) for screening varietal dure to rear stem borers year-round, to larvae have pupated, plants are cut 15 cm resistance help speed screening for varietal resis- above the base. The trays with stubbles tance. are transferred to a 2- × 1- × 1-m screen R. C. Saxena, F. G. Medrano, and L. M. Sunio, Seedlings of IR62 (susceptible to YSB, cage for adult emergence. About 80% of Entomology Department, IRRI resistant to other insect and tungro the infested tillers produce moths. viruses) are transplanted weekly in 34- × Emerging moths are collected daily YSB Scirpophaga incertulas (Walker) 25- × 11-cm plastic trays (see figure). At and transferred to oviposition cages with moths lay eggs on rice plant leaves. mid-booting, a 2.5-cm-long slit is made potted 40-d-old TN1 plants. Leaf cuts Shortly after hatching, the neonate larvae with a scalpel in the bulging middle por- with egg masses are removed from those bore into the plant tissues. Larval feeding tion of the leaf sheath below the flag leaf. plants two times a week and placed in 15- at the vegetative and reproductive stages The incision is dilated to expose a small × 1.5-cm test tubes or small ball jars. causes deadhearts (DH) and whiteheads. portion of the developing panicle. One to At 27 ± 2 °C, eggs hatch in about a Many cultivars are susceptible to YSB, two first-instar YSB larvae are released week. Emerging larvae are used for and even moderate host plant resistance is onto the panicle and the incision closed. varietal screening, for basic studies, or for maintaining the insect culture.

MDU3, a new gall midge- resistant rice

S. Jebaraj, G. Soundarapandian, M. Subramanian, M. S. Venugopal, and G. Logeswaran, Agricultural College and Research Institute, Madurai 625104, Tamil Nadu, India

Our breeding work for gall midge (GM) Orseolia oryzae Wood Mason resistance identified a superior rice culture ACM8. In screenhouse and field tests in the endemic area, ACM8 yielded higher than highly susceptible IR20. ACM8 has been released as MDU3 exclusively for the GM endemic area. MDU3 (IET6012) is a derivative of a cross involving IR8 and Warangal 1263. Grain yields in experiment station trials averaged 4.7 t/ha, 22.4% higher than IR20 (Table 1). In adaptive farmers’ field trials at 24 locations, ACM8 yields averaged 4.9 t/ha, 10.9% higher than IR20. In na-

Table 1. Overall performance of MDUJ and IR20 in Tamil Nadu, India.

Increase Trial MDU3 IR20 over IR20 (%)

Grain yield (t/ha) Research station 4.7 3.8 22.4 trials a Adaptive research 4.9 4.4 10.9 trials b AICRIP trial c 4.1 3.8 7.9 Productivity/d (kg/ha) 41.4 30.9 13.7

Steps in rearing YSB for resistance studies. a Mean of 6 yr. b Mean of 24 locations. c Mean of 7 centers.

IRRN 15:3 (June 1990) 15 tional yield trials at seven locations Table 2. Reaction to major insect pests and dis- nymphs at 20 DAS, and 75-80 adults at throughout India, performance was eases at Madurai, Tamil Nadu, India. 30 DAS . Thrips nymphs were mopped up encouraging. Overall performance Score a at 20 DAS by passing a wet palm 4-5 indicates yields 13.7% higher than IR20. Pest times across seedlings in the nursery and MDU3 is semidwarf with high tillering ACM8 IR20 freed by dipping the hand in a pail of (MDU3) ability and is nonlodging. It matures in water (see figure). We collected 200-250 120-125 d, 5-10 d earlier than IR20, and BPH (screenhouse) 3 7 thrips per sweep. has high productivity per day. The grain is WBPH (screenhouse) 5 7 Water containing thrips collected per Gall midge long and slender with white rice; cooking Screenhouse 0 7 25 sweeps was poured uniformly on 7-d- quality is good. Field 0 9 old seedlings of test cultivars (including ACM8 was screened under artificial as Leaffolder 3 7 resistant Ptb 21 and susceptible TN1) Blast (field) well as field conditions for the important Leaf 3 3 grown in wooden trays (60 × 40 × 10 cm) pests and diseases (Table 2). It is highly Neck 3 5 inside a large water-filled iron tray. Each resistant to GM; resistant to brown plant- Brown leaf spot (field) 5 3 seedling was infested with 5-6 nymphs. Sheath rot (field) 3 3 hopper (BPH), leaffolder, and blast and Alternatively, water containing thrips moderately resistant to whitebacked plant- a By the Standard evaluation system for rice. was poured on 30-d-old TN1 plants kept hopper (WBPH) and brown leaf spot. inside a water-filled tray. Nymphs settled readily on TN1 plants, which were then tapped gently over seedling trays for Using rice nurseries to col- Greenhouse cultures have failed to infestation. Using thrips collected this lect thrips for use in provide the thousands of thrips needed. way, we were able to screen 400 entries screening rice germplasm We developed a simple technique to for resistance. The technique can be used collect thrips directly from rice nurseries. in areas where dry weather prevails for 3- R. Velusamy, Tamil Nadu Agricultural The nurseries are sown every 2 wk during 4 mo. Thrips populations peak with the University (TNAU), India; and R. C. Saxena, peak thrips incidence. onset of dry weather; heavy rains wash IRRI Pregerminated IR64 seed was sown in them away. 7- × 1-m beds Aug-Oct 1988 in Coimba- Breeding for resistance to thrips tore. At 10, 20, and 30 d after sowing Stenchaetothrips biformis (Bagnall) has (DAS), seedlings were examined under a Pest resistance- lagged because of the lack of large pest binocular microscope. Thrips population/ other pests numbers needed for screening germplasm. seedling was 5-6 adults at 10 DAS, 60-70

Reaction of rice cultivar Faro 11 to sugarcane cyst nematode Heterodera sacchari

O. A. Fademi, Rice Research Programme, NationaI Cereals Research Institute, Badeggi, P.M.B. 8, Bida, Niger State, Nigeria

H. sacchari (Luc and Merny) is wide- spread in sugarcane cropping areas of Nigeria. In many of the mid-belt states of Nigeria, rice and sugarcane are intercropped or relay-cropped. In earlier screening of some rice varieties, all were susceptible to H. sacchari. We studied H. sacchari pathogenicity on rice. Ten-liter plastic buckets were filled with soil collected from an H. sacchari- endemic field at the Nigerian Sugar Company plantation, Bacita, and planted with rice cultivar Faro 11. Inocula were Schematic of procedure for collecting rice thrips from nurseries to use in screening rice germplasm juveniles emerging from cysts collected for thrips resistance. earlier from the same field using a

16 IRRN 15:3 (June 1990) The rice crop is exposed to low tem- (from ITA212/B2161C-MR-57-1-3-1), Effect on rice of H. sacchari at various inoculum levels. a Niger State, Nigeria perature (13-20°C) and associated disease have been identifed as promising. Their problems (sheath rot [ShR] and glume overall performance over 3 yr (1986-88) Inoculum level Panicle in on-station trials at Bamunka, Ndop (nematodes/ Tiller no. exsertion discoloration [G1D]). Low air and water plant) (cm) temperatures, low light intensity, high Plain, was good. Grain yields averaged relative humidity, and intermittent strong 6.3 and 5.8 t/ha (Table 1). In researcher- 0 6.55 a 10.50 c winds are yield constraints. managed trials at Dschang (alt. 1,400 m) 1,000 4.56 c 12.55 ab Agronomic studies have shown that during 1988, TOX3344-TOC-34 and 5,000 4.25 c 13.28 a changing the planting time is an alterna- TOX3145-TOC-34-2-3 yielded 5.5 and 10,000 5.09 b 11.63 bc tive to escape low temperatures during 4.6 t/ha, respectively. Highest yields so a Mean separation by DMRT. critical late vegetative and early flowering far were 7.1 t/ha for TOX3344-TOC-34 phases. However, the present area is and 6.3 t/ha for TOX3145-TOC-34-2-3. cultivated by more than 6,000 small far- TOX3145-T6C-34-2-3 and Fenwick can and incubated in petri mers, with limited ability to adopt this TOX3344-TOC-3-4 show greater dishes. Inocula were applied at 1,000, practice. tolerance for low temperature and greater 5,000, and 10,000/plant. Steam-sterilized Varieties that fit a longer range of resistance to ShR and G1D (Table 2). soil was the control treatment. The planting times are needed. IR7167-33-2-3 Panicle tip degeneration was more severe experiment was laid out in a completely was released in 1986 to replace Tainan 5. in IR7167-33-2-3 and Tainan 5; this is randomized block design with four Its medium, bold, and fairly chalky grain believed to cause direct yield losses. replications. type was an improvement over the short, TOX3344-TOC-3-4 and TOX3145- Both tillering and panicle exsertion bold, and chalky grains of Tainan 5. TOC-34-2-3 have long, slender, translu- were affected significantly by increasing IR7167-33-2-3 and Tainan 5 yield an cent grains and, when cooked, are flaky, levels of H. sacchari (see table). Above average 3.5 and 3.0 t/ha under farmers' a characteristic preferred by farmers and the 5,000 inoculum level, nematode management. The need is for suitable local consumers. Palatability tests in influence was less pronounced. This may high-yielding varieties with long, slender, 1988 placed TOX3344-TOC-3-4 as best be related to the self-regulatory property translucent grain. in cooking quality and taste. It is a of H. sacchari populations under limited Two advanced lines, TOX3344-TOC- candidate for release for general cultiva- food supplies: some juveniles die while 3-4 (derived from TOX3117-18-1/ tion at Ndop Plain. others undergo sex change into nonpara- ITA212) and TOX3145-TOC-34-2-3 sitic male forms. Table 1. Characteristics of promising varieties or advanced lines for irrigated conditions at Ndop Plain, Stress tolerance– Northwest Cameroon. Grain Plant Growth Yield b adverse temperature Cultivar type a height duration (t/ha) (cm) (d)

TOX3344-TOC-3-4 L/S 90 120 6.3 Promising cold-tolerant and TOX3145-TOC-34-2-3 L/S 83 120 5.8 high-yielding rice lines for IR7167-33-2-3 c M/B 100 110 4.6 Ndop Plain, Northwest Tainan 5 c S/B 95 111 3.8

Cameroon a L/S = long and slender, M/B = medium and bold, S/B = short and bold. b Yields averaged over 8 on-station trials 1986-88. c Currently recommended variety. M. P. Jones, S. B. C. Wanki, A. C. Roy, and J. A. Ayuk-Takem, IRA/NCRE/USAID/IITA Rice Project, Dschang, Cameroon, and UNVDA, Table 2. Reaction of promising varieties or advanced lines to low temperature and associated diseases at Ndop, Northwest Province, Cameroon Ndop Plain, Northwest Cameroon. Low temperature a Disease score a Rice in Cameroon grows over a broad range of climatic conditions, from a dry Cultivar Visual score Panicle tip ShR GlD 4 WT degeneration tropical climate with less than 800 mm (0-9) 2 WF (%) rain in the north to a humid tropical climate with more than 2,000 mm rain in TOX3344-3-4 3 5 1 1 the northwest and west. At Ndop Plain TOX3145-TOC-34-2-3 3 5 3 3 b (1,200 m above sea level) in the north- IR7167-33-2-3 5 10 3/5 3 b west, about 3,000 ha is planted to Tainan 5 1 20 3/5 5 irrigated rice with a potential for 15,000 a WT = weeks after transplanting. WF = weeks after flowering. b Currently recommended varieties. Scored with the Standard ha. evaluation system for rice.

IRRN 15:3 (June 1990) 17 a Performance of cold-tolerant Some agronomic traits of selected cold-tolerant rice genotypes at Chhomro (altitude 2000 m), Nepal, 1989. varieties in western hills of Plant Tillering Cold Panicle Sheath Nepal Genotype vigor ability tolerance exsertion rot (1-9 scale) (1-9 scale) (1-9 scale) (1-9 scale) (1-9 scale) B. R. Sthapit, Crop Science Section, Lumle Akiyudaka 7 9 5 5 3 Agricultural Centre, P.O. Box No. 1, Pokhara, Chhomro Local (check) 3 5 5 1 1 Kaski, Nepal Fuji-102 9 9 7 5 3 IRI-353 3 5 3 5 3 A large portion of rice in Nepal is grown K335 9 9 7 5 3 at 1000-2000 m above sea level, where NR10157-2B-17-2 9 9 9 5 7 Palung 2 7 7 low temperatures cause cold damage. 9 5 5 Rakshali 5 5 5 5 3 Most varieties grown in high altitudes are Rodina 9 9 7 5 5 indigenous. We evaluated 28 genotypes Stejaree 45 9 9 5 3 3 in 1989 at our Chhomro off-station Bhutan 11 9 9 5 3 3 research site (2000 m above sea level). B4190E-CW-139-29-176 7 5 9 5 3 They were indigenous varieties Raksali, B4448E-35R-1 7 7 9 5 3 Cheonmabyeo 9 7 7 3 3 Palung 2, and Chhomro local and Chhomro (check) 5 3 5 1 1 materials obtained from IRRI, and the IR15579-166 7 7 9 5 3 Nepal Rice Improvement Program, IR23325-R-R-B-7-2-2 5 5 9 3 3 Parwanipur, and Botany Division, IR26036-2-2-2-3 7 7 7 5 7 Khumaltar. Ml0l 7 5 5 3 3 NR10157-2B-13-1 Water temperature during anthesis 7 7 7 5 3 NR10157-2B-13-5 5 5 1 5 5 (Oct-Nov) was 20.2 °C; mean minimum NR10157-2B-17-1 9 5 7 5 7 temperatures were 15.1-16.5 °C; mean NR10167-2B-7 3 5 7 5 3 maximum, 16.3-19.7 °C. During early NR10164-2B-14 7 3 9 5 7 seedling growth (Jun-Jul), minimum tem- NR10167-2B-16 7 7 9 5 7 peratures were 14.5-16.4 °C and maxi- NR10177-B-11 7 5 9 5 3 NR10180-B-13-3 7 5 mum temperatures, 21.9-23.1 °C. 7 5 7 NR10180-B-13-4 7 7 7 5 5 Agronomic traits for cold tolerance Seto Bhakunde 3 5 5 1 3 were good in some exotic varieties (see a table). Spikelet sterility was 100% in all By Standard evaluation system for rice scale. Only Chhomro Local, Chhomro, and Seto Bhakunde gave some yield. genotypes except Chhomro local (14%) and Seto Bhakunde (25%). Those local materials such as China 1039, Akiyudaka, indigenous varieties from the Himalayan varieties produced some yield. and Stejaree 45 failed to set grain. belt for use in the breeding program for Internationally known cold-tolerant This suggests a need to evaluate more cold-tolerant rices.

Screening rice for The cold season is characterized by no (Harmattan is the northeasterly cold wind temperature tolerance in rainfall, high and frequent cold harmattan that blows from Europe, across the Medi- northern Nigeria wind. low minimum but relatively high terranean and Sahara desert, and down the maximum temperature, low relative coast of West Africa.) W. N. Umeh, National Cereals Research humi-dity, hazy and dusty atmosphere, Atmospheric demand for moisture (in- Institute, P.M.B. 1022, Birnin Kebbi, Sokoto and high evapotranspiration (Table 1). dicated by piche evaporation) is high from State, Nigeria Table 1. Climatological data for cold and bot months. a Northern Nigeria, 1988. Most rice production in Nigeria is restric- Temperature (°C) ted to the wet season, with a long fallow Month Rainfall Wind speed Piche evaporation between seasons. Irrigation schemes in (mm) Maximum Minimum (kg/h) (ml/d) the northern states provide an opportu- nity to overcome contingent drought and October 0 36 23 158.40 14.5 November 0 35 20 188.22 19.5 increase rice production through better December 0 30.4 17.3 245.47 21.9 land utilization. January 0 30.9 17.6 294.92 23.9 Development of temperature-tolerant February 0 34.3 19.7 283.20 26.6 rice varieties would help reduce the long March 0 38.8 26.0 261.55 29.7 40.0 28.2 243.1 21.6 fallow in areas with 3-4 mo of cold wea- April 5.8 May Trace 40.3 29.3 250.2 19.8 ther (Nov-Jan/Feb) and 3-4 mo hot weather (Feb-May). a Courtesy of the Meteorological Department, Sokoto Station, Nigeria.

18 IRRN 15:3 (June 1990) Nov to May compared with Jul-Sep. Irri- gation water, air, and soil surfaces are Stress tolerance–adverse soils cold. (This also affects labor productivity.) Phosphorus activity in correlation coefficients were estimated, We screened 100 rice lines for cold genotypes with low and path analysis done. tolerance in 1987-88. Lines were seeded phosphorus tolerance P content in leaf at 60 d showed a 18 Dec 1987. Eight failed to germinate. significant negative correlation ( r g = Seedlings in the nursery exhibited stunted N. D. Majumder (Present address: Central -0.413) with sound grain P (see table); growth, leaf yellowing, scorched leaf Agricultural Research Institute, Port Blair other correlations were not significant tips, retarded tillering, and poor root de- 744101, India), S. C. Rakshit, and D. N. Root P had a significant, positive velopment. Borthakur, ICAR Research Complex, Shillong association with P content in stem ( r p = Seedlings were transplanted 18 Feb 793004, India 0.603, r g = 0.722). leaf ( r p = 0.419, r g = 1988 in nonreplicated 4- × 6-m micro- 0.507), and sound grain ( rp = 0.525, r g = plots. Average plant height at transplant- Seven P-tolerant varieties (IR28, IR29, 0.588) at both the phenotypic and ing was 6 cm. Twenty entries died after IR30, Khonorullo, Mirikrak, Pawnbuh, genotypic levels. A significant, positive transplanting. and Ngoba) and their 21 cross combi- association was found between P content Irrigation was from tubewells, and nations made in a diallel fashion in stem and leaf at harvest; that between was maintained at 13-15 cm depth. As without reciprocals were sown in upland grain yield and plant was significant and general weather conditions improved lateritic soil deficient in P (5 ppm negative at phenotypic and genotypic toward the end of Feb, seedlings became available P, pH 5.0). The experiment was levels. more vigorous. laid out in a randomized block design The effect of P activity through Eight entries had 100% empty glumes; with three replications. Spacing was 20 different pathways and its role in yield incidence of sterility in the remaining 64 cm between plants and between rows. was determined using genotypic and entries ranged from 18 to 60%. This may Plant tissue analysis was done 60 d phenotypic correlation coefficients. The be attributed to high temperature and after seeding (leaf) and at harvest (root, genotypic correlation had a higher high winds at anthesis in late Mar to early leaf, stem, panicle without grain, and magnitude. The highest direct positive Apr. sound grain). Genotypic and phenotypic contribution was made by P in the root Plant height at maturity ranged from 69.4 to 95.0 cm; days to 50% flowering Phenotypic and genotypic correlation a coefficients of P content in leaf at 60 d growth, different organs at ranged from 105 to 142 (Table 2). harvest, and grain yield per plant and direct contributions to yield. The best 18 entries were selected for Correlation coefficients of P content b further advanced yield trials 1988-89. At 60 Direct Table 2. Growth characteristics and grain yield of d growth At harvest effect cultivars selected for cold tolerance. a Nigeria, 1987- 88. Leaf Root Stem Leaf Panicle Grain without Days to Plant Grain yield grain Cultivar a 50% height g/pot (1) (2) (3) (4) (5) (6) flowering (cm) (2.4m 2 ) (1) 0.230 RNR74229 122 83.3 1380 0.280 RTN76-2-1-1-1 127 90.4 1300 (2) r -0.093 0.211 IR13538-48-2-3-2 115 79.2 1230 p -0.112 0337 IR27325063-2-2 122 84.4 1180 r g BR161-23-59 122 75.2 1180 (3) r p 0.044 0.603** 0.051 FAROX233-1-1-3 127 82.2 1160 0.070 0.722** 0.080 C1321-2 122 72.4 1140 r g IR24594-272-2-2 121 95.0 1120 (4) r p 0.184 0.419* 0.634** -0514 KUA1727 127 90.6 1120 r 0.185 0.507** 0.726** -0.669 BG367-4 105 84.4 1100 g IR28210-68-4-1-3 109 80.2 1100 (5) r p -0.292 0.057 0.062 0.260 0.028 IR28118-138-2-3 142 90.4 1100 -0.347 0.075 0.065 0.288 0.038 r g ITA302 122 83.4 1080 lTA121 111 69.4 1060 (6) r p -0.353 0.525** 0.332 0.292 0.237 -0.080 -0.413* 0.588** 0.359 0.303 0.241 -0.135 C1158-7 138 77.4 1040 r g 16439 116 74.4 1040 BG276-5 105 80.0 1000 c (7) r p 0.154 -0.039 -0.166 -0.382* -0.232 -0.190 - ET6279 122 80.2 1000 c r g 0.167 -0.052 -0.189 -0.418* -0.255 -0.217 - aCold tolerance score for these entries is 5 by the Standard a b c evaluation system for rice. r p , r g phenotypic and genotypic correlation coefficients. Significant at 5% (*) and 1% (**) levels. For grain yield/plant.

IRRN 15:3 (June 1990) 19 (0.337) at harvest, followed by P in leaf positive. An indirect positive effect was Manoharsali as checks were field tested at 60 d and in stem at harvest. The found via stem at harvest. The direct and at research stations and in field trials in indirect effects of P in stem, grain, leaf, indirect contributions of leaf and sound Gerua, Tinsukia, and Suklivoria for 1-6 and sterile panicles via root were all grain were negative. yr. Trials were laid out at 20- × 15-cm spacing with 2-3 seedlings/hill. Forty kg N as urea was applied in three splits Integrated germplasm improvement before planting, at tillering, and at panicle initiation; 20 kg/ha each of P and K were IET6666, a new high-yielding 23 by the Directorate of Rice Research in applied in the form of single super- rice variety for Assam Hyderabad, is suitable for low-lying phosphate and muriate of potash as basal. fields and cloudy weather conditions IET6666 showed wide adaptability K. Chandra, D. K. Barua, U. Kalita, D. during wet season. Its coarse grain and and stability in grain yield under the Dutta, and B. Bharali, Assam Agricultural intermediate plant height are preferred by agroecological conditions of Assam University, Regional Agricultural Research the majority of farmers in Assam. (Table 2). It flowered in 115-120 d and Station, Titabar 785630 (Assam), India Agronomic characteristics are given in matured in 145-157 d. Table 1. The variety is being evaluated for IET6666, a long-duration, high-yielding IET6666, 12 other promising cultivars release as Lakhimi for Assam wet variety evolved from RP31-49-2/Patnai with similar duration, and Mahsuri and season.

Table 1. Morphological and physiological charac- Table 2. Yields of IET6666 and check varieties at different locations in Assam, India 1978-88. teristics of IET6666 and check variety Manohar- sali at Titabar, Assam, India. Yield (t/ha) Year Location IET6666 Mahsuri Manoharsali Character IET6666 Manoharsali 1978 Titabar 3.4 2.7 - Plant height (cm) 118.73 148.53 Karimganj 3.0 3.3 - Duration 145 148 1979 Titabar 5.2 3.8 - Panicles (no./m 2) 257 242 Karimganj 2.9 3.9 - Filled grains (no./ 103 83 5.0 4.5 - panicle) 1980 Titabar 1000-grain weight (g) 23.22 24.55 Karimganj 3.6 3.5 - Total dry matter at 116.76 146.56 1982 Titabar 3.8 - 3.0 flowering (kg/ha) Karimganj 4.4 - 1.9 Leaf area index 4.58 5.80 1983 Titabar 3.9 - 2.0 Total chlorophyll 2.23 3.43 Karimganj 4.4 - 3.5 content at flowering 1984 Titabar 5.3 - 3.1 (mg/g fresh wt) 1985 Titabar 5.3 - 3.2 N content in leaf tissues 2.18 1.23 1986 Titabar 5.2 - 3.2 at flowering (%) - Solar energy utilization 1.87 0.81 1987 Titabar 5.4 3.2 efficiency for dry 1988 Titabar 5.1 - 2.6 matter (%) 1984 on-farm trials Gerua 6.4 - 5.2 Solar energy utilization 0.55 0.25 Tinsukia 5.1 - 4.2 for grain yield (%) Suklivoria 3.9 - 4.0

Performance of IR46 and Table 1. Yields of IR46 and IR10781-143-2-3 at 4 sites in subtropical Nepal, 1983-86. lR10781-143-2-3 under trans- Yield (t/ha) Increase planted rainfed lowland Variety over Experiment site a conditions in Nepal Tarahara Parwanipur Rampur Nepalganj Mean check(%) and time IR46 4.6 2.6 3.0 3 2 3.4 142 Research stations, G. L. Shrestha and A. C. Shrivastava, Improved check 2.4 2.2 2.0 2.8 2.4 100 1983-84 National Rice Improvement Program (NRIP), Bindeshori IR46 4.8 2.6 2.4 4.2 a 3.5 114 Farmers' fields, Parwanipur Agriculture Station, Birganj, Improved check 3.3 2.0 - 3.9 3.1 100 1985-86 Nepal Masuli IR10781 3918 2956 2692 2981 3.1 105 Research stations, In Nepal, 88% of the rice area (1.45 Improved check 3 562 3001 2512 2897 3.0 100 1984-85 Bindeshori million ha in 1988) is in the subtropical IR10781 4840 2818 3750 4150 3.9 127 Famers' fields, climatic region of the Tarai belt (67-250 Improved check 3292 2012 - 3900 3.1 100 1985-86 m altitude), the Inner Tarai region, and Masuli equivalent climatic region of river basin a Farmer's field result of this location is from Nawal Parasi area. Each location includes the results from various farmers' areas and valleys up to 900 m altitude. fields.

20 IRRN 15:3 (June 1990) Under assured irrigation, two crops of Table 2. General agronomic characters of IR46 and IR10781-143-2-3 under transplanted rainfed lowland conditions in subtropical Nepal. a rice are grown during the summer (Feb- Jun) and rainy (Jun-Oct) seasons, with a Heading Maturity Culm length Panicles Av yield 2 nonrice winter crop grown Nov-Jan. Variety (DAS) (DAS) (cm) (no./m ) (t/ha) More than 75% of the country's IR46 108 135 96 229 3.4 ricefields are rainfed, dependent on the IR10781-143-2-3 105 137 92 233 3.5 monsoon. We are trying to identify high- Masuli (most popular) 119 150 100 231 3.0 yielding rice varieties suitable for trans- a DAS = days after seeding. planted rainfed lowland conditions. IR46 and IR10781-143-2-3 have ha under rainfed lowland conditions (the crops such as wheat, winter maize, or shown consistently better performance national average rice yield is 2.2 t/ha). winter legumes. They are resistant to over recommended check Bindeshori and Both entries mature at least 10 d major diseases bacterial blight and blast. popular improved variety Masuli earlier than Masuli in the normal (Jun- They are being distributed to farmers (Mahsuri) in trials for the last 5 yr (Table Oct) planting season (Table 2), giving through the rice minikit program. 1). Yields have averaged more than 3.0 t/ enough time for farmers to plant winter

Seed technology Harvesting 27 d after 50% anthesis gave AF-P bags, and had higher electrical con- the lowest electrical conductivity and ductivity. The interaction was significant. Using electrical conductivity highest germination (see table). Harvesting The increased electrical conductivity of to determine maturity stage 41 d after 50% flowering gave the highest seeds harvested 41 d after 50% anthesis in for quality rice seeds electrical conductivity and lowest germina- storage showed that they are less vigorous K. Sivasubramanian and T. V. Karivara- tion. Seeds stored in cotton cloth bags and deteriorate faster than seeds harvested tharaju, Tamil Nadu Agricultural University, deteriorated more than those stored in P- 27 d after 50% anthesis. National Pulses Research Centre, Vamban 622303, India Electrical conductivity of IR50 seeds stored for 9 months. National Pulses Research Centre, Vamban, India, 1985 wet season. We studied the influence of maturity Electrical conductivity a (dS/m) stage on the keeping quality of seeds. IR50 grown during 1985 wet season was Harvest date At 3 mo after 6 mo after 9 mo after Germi- harvested at 27, 34, and 41 d after 50% (d after harvest harvest harvest harvest Mean nation 50% anthesis) (%) anthesis. Seeds were dried to 8% mois- C1 C2 C1 C2 C1 C2 C1 C2 ture content, treated with captan (N- trichloro methyl thio)-Cyclohex-4-ene- 27 Untreated 36.85 36.83 37.61 37.12 39.62 37.18 40.20 37.25 37.83 93 36.83 36.83 37.26 37.10 39.80 37.16 40.18 1,2-dicarboximide), and stored in cotton Treated 37.20 37.80 96 and paper-aluminum foil-polythene 34 Untreated 39.41 39.41 40.68 39.86 41.86 40.75 44.86 41.86 41.08 92 laminated (P-AF-P) containers for 9 mo. Treated 39.41 39.41 41.61 39.68 42.12 39.86 43.86 40.28 40.78 95 Electrical conductivity of the seed 41 Untreated 48.64 48.64 53.63 49.24 55.32 51.24 61.23 51.83 52.47 89 leachate was measured at 3-mo intervals Treated 48.64 48.64 50.24 49.07 54.83 50.61 60.20 51.61 51.73 90 using Elico CM-82 Conductivity bridge. Mean 41.63 41.63 43.51 42.01 45.59 42.80 48.42 43.34 Leachate was prepared using 50 Germination(%) 94 94 91 94 90 90 89 94 randomly selected seeds, soaked in 50 ml LSD (0.01) 0.63 0.59 0.39 0.39 0.55 0.39 0.38 0.45 0.45 0.32 of deionized water for 24 h at room a C1 = cotton bags, C2 = P-AF-P containers. temperature, with two replications.

Space limitations prevent IRRN from Mid-storage correction to conditions. After 8 mo, half the seeds publishing solely yield data and yield prolong viability of rice were soaked in double their volume of a component data from routine seeds dilute sodium dihydrogen phosphate germplasm screening trials. Publication solution (10 -4 M) for 6 h, sun-dried to is limited to manuscripts that provide ei- 8.5%, and re-stored for 24 mo. ther a) data and analysis beyond yield C. Dharmalingam, Agricultural College and and yield components (e.g., multiple or Research Institute, Madurai 625104, Tamil Hydrated seeds maintained high unique resistances and tolerances, Nadu, India germination and vigor (in terms of root broad adaptability), or b) novel ways of length) (see table). Nonhydrated seeds interpreting yield and yield component We stored seeds of rice cultivars ADT36. lost vigor and viability. Medium-duration data across seasons and sites. Bhavani, and CO 40 at 8.5% moisture cultivar Bhavani had lower storage content in cloth bags under ambient potential than CO 40 and ADT36.

IRRN 15:3 (June 1990) 21 Germination and vigor of hydrated rice seeds after 3 periods of storage. Tamil Nadu, India. Straw and grain yield increased significantly with incorporation of mesquite, After storage Biological withania, and country mallow residues, Cultivar Parameter Initial 8 mo 12 mo 32 mo loss (%) and of neem leaf (see table). duration Control Hy- Control Hy- Control Hy- Control Hy- drated drated drated drated Effect of seeding rate on dry ADT31 matter production and Short Germination 86 82 90 73 89 45 85 47.7 1.2 nitrogen accumulation of (%) Root length 19.5 17.6 22.1 15.0 20.0 9.2 17.8 52.8 8.7 Sesbania rostrata (cm) Bhavani K. H. Diekmann and S. K. De Datta, Agron- Medium Germination 90 84 95 75 86 16 85 82.2 5.6 omy Department, IRRI (%) Root length 18.2 16.0 17.6 15.0 19.5 10.4 18.2 42.8 – (cm) Increased crop seeding rates result in CO40 increased plant competition for nutrients Long Germination 89 86 94 78 88 27 87 69.7 2.2 and light. We evaluated the effect of (%) Root length 20.7 18.9 21.1 17.7 20.2 11.5 19.0 44.4 8.2 different seeding rates on dry matter (cm) production and N accumulation in Sesbania rostrara, a stem-nodulating legume and potential green manure crop for lowland rice. The field experiment was conducted in CROP AND RESOURCE 1987 wet season. Soil was a Maahas clay (Tropaquept) with pH 6.3; 11 g organic MANAGEMENT C/kg; 1.2 g total N/kg; and cation exchange capacity, 34 cmol/kg. P (20 kg/ Soil microbiology ha) as single superphosphate was organic C, 0.073% N, 9.7% CaCO 3, broadcast and incorporated before 0.15% TSS. Each pot held 8 kg soil. seeding. Seeding rates were 20, 30, 40, Influence of wild plant and For the wild plants, treatments were and 50 kg sesbania seeds/ha, laid out in a crop residues on rice yield 3 g residue/kg soil (about 6 t/ha) plus 25 factorial randomized complete block mg N/kg (about 50 kg N/ha). For the crop design with four replications. Plot size 2 S. M. Alam and A. R. Azmi, Atomic Energy residues, treatments were 3 g residue/kg was 20 m . Agricultural Research Centre, Tandojam, soil plus 50 mg N/kg soil. Each pot also Sesbania seeds pretreated for 30 min Pakistan received 25 mg P/kg soil. Rice cultivar with concentrated sulfuric acid were Shadab was transplanted at 4 seedlings/ broadcast into well-leveled, water- Plant residues and farmyard manure are pot. Pots were arranged in a randomized saturated soil. The field was kept added to soils to improve their organic block design with four replications. N saturated to 7 d after seeding, then matter content and productivity. This application was lower for the wild plants flooded to 0.05 m. traditional agricultural practice has because their very high antibiotic activi- Sesbania was harvested 45 d after primarily been used to increase soil ties tended to inhibit nitrification. seeding. Plant fresh and dry weights were humus content, water-holding capacity, measured and plant density determined water infiltration rate, aeration, and Effect of incorporating plant residues on rice from a 7-m 2 area A subsample (4 × 1 m straw and grain yieids. a porosity; to ameliorate soil temperature; per plot) was taken to determine leaf and and to supply some essential plant Straw yield Grain yield stem dry matter separately and to analyze b nutrients. Treatment (g/pot) (g/pot) N concentrations in leaf and stem. Total In a pot study, we evaluated the effect Control (no residue) 17.45 c 11.70 b N accumulation was calculated. of incorporating residues of mesquite Mesquite 28.80 a 24.97 a N concentrations in leaf and stem did ( Prosopis glandulosa ), withania Withania 23.92 b 19.62 a not differ significantly with seeding rate Country mallow 24.62 b 22.00 a ( Withania somnifera ), and country Rice husk 16.05 c 11.62 b (see table). Seeding at 40 kg/ha gave the mallow ( Abutilon indicum ) with rice Wheat straw 16.92 c 10.75 b highest total N accumulation per plant ( Oryza sativa ) husks and wheat ( Triticum Rice straw 18.05 c 12.10 b (114 kg N/ha), and highest fresh and dry Neem leaf 25.22 b 20.67 a aestivum) and rice straw, neem Farmyard manure 17.92 c 10.22 b matter production. Seeding at 50 kg/ha ( Azadirachta indicum ) leaves, and gave lower fresh and dry matter produc- a farmyard manure on straw and grain In a column, means followed by the same letter are not tion and N accumulation than seeding at significantly different (DMRT p<05). b Plant residue and yields of rice. Soil had pH 7.6, 0.95% farmyard manure were applied at 3 g/kg soil. 40 kg/ha.

22 IRRN 15:3 (June 1990) Plant density, dry matter production, N concentration, and N accumulation of Sesbania rostrata at These results suggest that the higher different seeding rate IRRI farm, Philippines, 1987 wet season. plant densities resulting from seeding Dry matter Plant Total rates above 40 kg/ha decrease organic Seeding rate (mg/ha) density Leaf N Stem N plant N matter production and N accumulation of 2 (kg/ha) (plants/m ) (g/kg) (g/kg) (kg/ha) sesbania plants. A plant density of 100 Leaf Stem plants/m 2 seems to be optimum for 20 1.2 2.7 55 46 9 81 maximum N accumulation. 8 85 30 1.3 3.0 70 46 To achieve a plant density of about 107 47 9 114 40 1.6 4.1 2 50 1.5 3.9 119 46 8 100 100 plants/m , seeding rates may have to LSD (0.05) 0.1 0.3 10 2 1 8 be adjusted for soil textures, climates, and field conditions.

~~ Physiology and plant nutrition seedling height, seedling dry weight, and leaf number were recorded 25 d after seeding. Effects of a growth regulator Triacontanol increases plant height and In general, seedlings treated with on rice seedling growth weight within a few days of application TRIA were superior to those with no and stimulates nutrient assimilation. treatment (see table). Late-maturing J. Ahmed, Rice Research Station, Chinsurah, Seeds of semidwarf IET4094 and NC492 and IR42 showed better results West Bengal, India IR42 and tall indica NC492 rice varieties than medium-maturing IET4094 in all were soaked 1 h before sowing in 3 treatments, for all characters. No toxic, Growth regulator Triacontanol has been concentrations of TRIA (n-Triacontanol): abnormal, or atypical morphological found effective in increasing biomass 0.01, 0.10, and 1.00 ppm, with three changes were observed at the concentra- production in cereals and vegetable crops. replications. Root length, root volume, tions used.

Effect of n-Triacontanol on rice seedling characters.

Root length (cm/plant) Root volume (ml/plant) Seedling height (cm/plant) Leaf no. per seedling Seedling dry wt (mg/plant) n-Triacontanol (mg/liter) lET4094 IR42 NC492 IET4094 IR42 NC492 IET4094 IR42 NC492 IET4094 IR42 NC492 IET4094 IR42 NC492

0.00 21.2 15.3 17.6 0.2 0.1 0.2 27.4 20.2 37.4 4.9 4.1 4.2 114 137 211 0.01 21.8 21.5 19.5 0.3 0.3 0.3 27.7 25.2 38.6 4.9 4.9 4.7 171 219 237 0.10 21.8 18.6 20.4 0.3 0.2 0.5 27.6 24.1 39.5 5.0 4.9 4.4 181 207 253 1.00 21.8 18.6 18.1 0.3 0.3 0.3 27.6 23.9 37.8 5.0 4.9 4.5 186 202 217

CV (%) 7.8 10.1 4.2 2.9 5.8 LSD (0.05) 2.6 0.1 2.1 0.2 18

Fertilizer management flowing floodwaters. A ready-made, Ustochrept, pH 8.0, CEC 33.0 cmol c /kg), balanced NP fertilizer and an alternative which in earlier experiments had respon- Greenhouse evaluation of application method are needed. ded to applied N and P. For a blanket urea supergranules (USG) Phosphatic fertilizers containing basal application, 100 mg K/kg (as KC1) . containing diammonium Ca(H2 PO 4 ) 2 H 2O (such as single or triple and 25 mg Zn/kg (as ZnSO 4) were incor- phosphate (DAP) for superphosphate [TSP]) are not compatible porated into the soil before transplanting. transplanted rice with urea because of an adduct formation Four hills (three 3-wk-old seedlings/ that leads to poor physical quality and hill) of IR36 were transplanted (20- × 20- N. K. Savant and S. H. Chien, International caking of USG briquettes. DAP, a com- cm spacing) in 2-wk presubmerged and Fertilizer Development Center (IFDC), P.O. mon fertilizer for transplanted rice in tro- puddled soil (32 kg air-dried basis) in a Box 2040, Muscle Shoals, Alabama 35662, pical rice-growing countries, is compat- wooden box (40- × 40- × 30-cm inside USA ible for preparation of USG. Agronomi- dimensions) with plastic lining. USG cally, deep placement of USG is efficient containing DAP (as tablets) was prepared Serious losses of fertilizer N and P to in transplanted rice. by compacting a mixture of prilled urea runoff are common in transplanted We conducted a greenhouse experi- (PU) and DAP in a 1:2 proportion. The rainfed ricefields of small farmers in ment to evaluate basal deep-placed USG amounts of N and P used (19.3 mg N/kg South and Southeast Asia. Losses occur containing DAP as NP fertilizer in trans- and 10.3 mg P/kg, equivalent to 40 kg N primarily because farmers are unable to planted rice. The experiment was laid out and 21 kg P/ha on area basis) were on the properly incorporate fertilizers into soils in a randomized block design with four steep portion of their response curves for with varying depths of nonflowing or replications. Soil was Vernon clay (Typic the soil used.

IRRN 15:3 (June 1990) 23 Effect of deep-placed USG containing DAP on grain yield and N and P uptake by transplanted IR36. Plant growth the first 3-4 wk after Greenhouse experiment, IFDC, USA, 1988. transplanting was markedly slower for Uptake by grains b deep-placed USG containing DAP (see b Grain yield (g/4 hills per box) table). However, grain yields and N and Treatment a (g/4 hills per box) N P uptake were statistically on a par with those for incorporated DAP, TSP, or Check 97 c 1.30 e 0.16 d partially acidulated phosphate rock USG deep placed at transplanting 130 b 1.78 cd 0.18 d (PAPR) and deep-placed USG. The PAPR TSP incorporated before transplanting 128 b 1.61 d 0.31 ab PU+DAP incorporated before transplanting 150 a 1.93 abc 0.32 a used was as effective as TSP in P availa- DAP incorporated before transplanting + PU 152 a 2.04 ab 0.31 ab bility. topdressed at panicle initiation These data suggest that deep-placed DAP incorparated before transplanting + 150 a 1.89 bc 0.34 a USG containing appropriate amounts of remaining N as USG deep placed at transplanting TSP incorporated before transplanting + USG 157 a 2.13 a 0.26 bc DAP may be a judicious choice as a NP deep placed at transplanting fertilizer for small farmers in transplanted USG containing DAP deep placed at transplanting 152 a 2.06 ab 0.26 c rice areas, especially rainfed, where PAPR incorporated before transplanting + USG 147 a 2.07 ab 0.24 c adequate incorporation of fertilizers is not deep placed at transplanting possible because of uncontrolled floodwa- a Rates of application: 19.3 mg N and 10.3 mg P/kg soil; 619 mg N and 329 mg P/4 hills per box. Estimated rate (on area basis), ter and nonavailability of suitable imple- 40 kg N and 21 kg P/ha. One USG was placed at 110-cm depth in the center of 4 rice hills with 20-*20-cm spacing. Incorporation means broadcast and incorporation up to 5-cm depth before transplanting with practically no floodwater. Fertilizer analysis: PU ments. Research under field conditions is and USG, 46% N; DAP, 21.2% N and 23.5% P; TSP, 20.9% total P; and PAPR from Central Florida (25% acidulation with H 3PO 4), under way in India to verify this. 15.0% total P. b Means in a column followed by the same letter are not significantly different at the 5% level by DMRT.

2 Rate and time of N Yield and panicles/m of direct seeded rice with graded rates and time of N application, Aduthurai, India. application for direct seeded Kuruvai Thaladi Samba Treatment irrigated rice Panicles Grain Panicles Grain Panicles Grain (no./m 2) yield (no./m 2 ) yield (no./m 2 ) yield O. S. Kandasamy and SP. Palaniappan, Tamil (t/ha) (t/ha) (t/ha) Nadu Agricultural University, Coimbatore 641003,India N rate (kg/ha) Kuruvai Thaladi and Samba We evaluated rate and time of N applica- 0 0 289 2.5 236 1.6 307 3.2 4.5 tion for irrigated rice on a clay loam soil. 40 50 327 4.3 308 2.8 374 80 100 362 5.0 332 3.3 434 5.1 Soil had pH 7.3 and 0.42% organic C. 120 150 383 5.2 351 3.5 453 5.3 Treatments were N at 0, 40, 80, and 120 LSD (0.05) 10 0.2 25 0.15 17 0.15 kg/ha in kuruvai (Jun-Sep) and 0, 50, 100, Time of application and 150 kg/ha in thaladi (Oct-Feb) and (initial 50% N) samba (Sep-Jan) seasons, and the initial At sowing - - 328 3.1 421 4.9 10 DAS 356 4.8 343 3.5 434 5.0 half of the N applied at four different 20 DAS 384 5.4 339 3.3 470 5.5 times in kuruvai (at 10, 20, 30 d after 30 DAS 346 4.7 325 3.1 398 4.7 seeding [DAS] and at active tillering) and At tillering 343 4.4 317 3.0 378 4.6 (LSD 0.05) 12 0.2 ns 0.19 22 0.19 at five different times in thaladi and samba (at sowing; 10, 20, 30 DAS; and at active tillering). The remaining 50% of N during thaladi when wet seeding was In general, yields increased with N was applied in two equal doses at active done. Water was maintained at 2-3 cm application in all three seasons (see table). tillering and panicle initiation stages, for topdressing. The responses to N application fitted except in treatments where the initial dose The experiments were laid out in a quadratic functions. itself was applied at active tillering. In this factorial randomized block design with Kuruvai Y = 2.6 + 0.05 N - 0.0003 N 2 treatment, N was applied in two splits, three replications. Short-duration TKM9, Thaladi Y= 1.6 + 0.03N - 0.0001 N 2 half at active tillering and half at panicle medium-duration IR20, and long- Samba Y = 3.1 + 0.03N - 0.0001 N 2 initiation. duration CR1009 were sown in kuruvai, The initial 50% N could be applied 20 N was broadcast as urea. Basal thaladi, and samba, respectively. Dry DAS in kuruvai and samba when dry fertilizer was incorporated in dry soil seeds were broadcast during kuruvai and seeding was done, and 10 DAS in thaladi during kuruvai and samba when dry samba; sprouted seeds were broadcast on when sprouted seeds were sown in seeding was done, and in the puddle puddled soil in thaladi. puddled soil.

24 IRRN 15:3 (June 1990) Grain yield with different modified urea materials, placement techniques, and nitrogen levels. Ralpur, Influence of modified urea India (1981-84 wet seasons). and placement on N use in irrigated rice Grain yield(t/ha) N(kg/ha) Urea form a 1981 1982 1983 1984 Mean R. Singh, S. K. Shrivastava, and J. M. Pandagare, IGKVV, College of Agriculture, 0 - 2.0 2.6 1.9 2.0 2.1 Raipur 492012, Madhya Pradesh, India 29 PU 2.3 3.1 2.7 - 2.7 58 PU 2.4 3.6 3.0 3.9 3.2 87 PU 2.8 3.4 3.4 4.4 3.5 Numerous N response experiments have 116 PU 2.9 3.9 3.7 4.4 3.7 shown that fertilizer N recovery by rice Mean PU 2.6 3.5 3.2 4.2 3.4 29 SCU 2.6 3 3 3.2 - 3.0 is seldom higher than 30-40%; even 58 SCU 3.1 4.0 3.8 4.0 3.7 with the best agronomic practices and 87 SCU 3.2 4.0 4.2 4.2 3.9 strictly controlled conditions, recovery 116 SCU 3.7 4.4 4.5 4.5 4.3 Mean SCU 3.2 3.9 3.9 4.3 3.8 seldom exceeds 60-65%. Using urea 29 USG 2.4 3.6 3.2 - 3.1 supergranules (USG) or urea briquettes, 58 USG 2.7 3.6 3.7 4.3 3.6 deep placed, has increased N efficiency, 87 USG 2.8 4.1 4.1 4.6 3.9 116 USG 3.1 3.6 4.3 4.8 4.0 and crop response to sulfur-coated urea Mean USG 2.7 3.7 3.8 4.6 3.7 (SCU) has generally been superior to LSD (0.05) 0.4 0.7 0.4 2.6 response to urea in a single dose and CV (%) 9.5 11.2 7.2 10.5

often to split applications. a PU was applied as best split, SCU was broadcast and incorporated, USG was placead 10-12cm deep in the soil We compared the efficiency of SCU, USG, and best split urea at different N levels in a randomized block design able bases (in meq/100 g) were 0.07 Na, 10-12 cm deep, and prilled urea (PU) best with four replications. The 4-yr experi- 0.63 K, 4.7 Mg, and 27 Ca. Available P split (see table). Yields increased with ment (1981-84) used medium-duration was 17 ppm by Bray method and 4 ppm increased N. Asha and Usha as test varieties. Soil by Olsen. Available Zn was 2.7 ppm. Highest N use efficiency was 32.1 kg was a Vertisol, clay loam texture, with Maximum yields at all N levels were grain/kg N as USG at 29 kg N/ha. Aver- pH 7.0,1.3% organic matter, 11% total obtained with SCU broadcast and aged over N levels, maximum N use effi- N, and CEC 33 meq/100 g. Exchange- incorporated, followed by USG placed ciency was 18.7 kg grain/kg N as SCU.

Influence of modified urea materials at different N rates on estimated wetland rice soil ammonium-N and nitrate-N

P. C. Pandey, G. L. Sharma. Pyare Lal, and P. S. Bisht, Agronomy Department, G. B. Pant University of Agriculture and Technology, Pantnagar Nainital 263145, Uttar Pradesh, India

+ - Changes in NH 4 -N and NO 3 -N levels in wetland soil can provide valuable insights into N losses and availability of N for + - rice. The NH 4 -N And NO 3 -N at 0-15 cm depth in flooded soil were measured at 15, 30, 45, and 60 d after transplanting (DT). The experimental area was Aquic Hapludoll (Mollisol of Tarai moist plains region about 30 km south of the foothills of the Shivalik Range of the Himalayas). Soil was silt loam with pH 7.9, 1.2% + organic C, 0.1% total N, 8 ppm available 1. NH 4 -N content in soil as influenced by N rates (a) and sources (b).

lRRN 15:3 (June 1990) 25 + - NH 4 -N, and 10 ppm available NO 3 -N. Pant Dhan 4 (134 d duration) was transplanted during 1985 and 1986 wet seasons (May-Oct). Urea supergranule (USG), sulfur- coated urea (SCU), and Musoorie phos- coated urea (MPCU) as basal incorporated and prilled urea (PU) applied as local split (1/2 at transplanting, 1/4 at tillering, 1/4 at 5-6 d before panicle initiation [DBPI]) and standard split (2/3 at transplanting and 1/3 at 5-6 DBPI) were applied at 29, 58, and 87 kg N/ha. MPCU and SCU were broadcast and incorporated at transplanting, USG was hand placed 8-10 cm deep in the center of 4 hills. Soil samples were collected randomly from fertilized plots, except in USG plots where they were collected 6-8 cm away from the placement site. + - NH 4 -N and NO 3 -N were extracted from the wet soil immediately with 1N + sodium sulfate. NH 4 -N concentration was determined by modified Nessler reagent - method and that of NO 3 -N by chro- motropic acid method. + NH 4 -N content increased with increasing N rates to 30 DT, then decreased (Fig. 1). The decrease may be attributed to uptake by plants, gaseous loss of NH 3 , and nitrification-denitrification. The decrease was less with USG. - NO 3 -N concentration was very low. At 15 DT, it was higher with PU and MPCU than with USG and SCU (Fig. 2). Plots - with USG showed lower NO 3 -N, pre- sumably because the USG was placed in a reduced zone where nitrification might be - 2. NO 3 -N content in soil as influenced by N rates (a) and sources (b). limited for lack of oxygen. With SCU, low - concentration of NO 3 -N could be due to The presence of nitrate suggests that These results suggest that formation of delayed release of urea and conversion of nitrification-denitrification losses may be soil nitrate can be reduced slightly through - fertilizer N to NO3 . occurring. the use of modified urea materials.

Contribution of flood silta- We evaluated the effects of siltation ponded by floodwater about 1.5 m deep tion to boro rice yield and by floodwater on boro rice in terms of the for about 15 d. response to N and K crop’s response to N and K fertilizer Jan- After the flood receded, three types of Apr 1988. Land within the Hathazari soil sampling were done: deposited M. Amin and M. Sadrul Amin, On-Farm Farming Systems Research area was surface silts, 2.5 cm; original soil, 2.5-15 Research Division, Bangladesh Agricultural Research Institute, Thakurgaon, Bangladesh Table 1. Characteristics of soil sample of flash-flooded ricefields Hathazarl, Bangladesh Jan 1988.

Floodwater deposits silt and other sus- Organic K NH 4 -N Zn S Soil sample pH matter (%) (meq/100 ml) (lg/ml) (lg/ml) (lg/ml) pended materials as it starts to recede. The effects of this silting on soil produc- 0-2.5 cm surface silt 6.6 2.35 1.0 22.5 3.0 8 tivity have not been established experi- 2.5-15 cm soil 5.9 2.45 0.3 17.5 2.5 4 0-15 cm~~~~ silt ~ and soil 6.0 2.50 0.3 19.5 3.0 7 mentally.

26 IRRN 15:3 (June 1990) cm; and whole sample, 0-15 cm. Soil Table 2. Yield parameters of boro rice planted on flash-flooded fields and fertilized with N and K, analytical data are presented in Table 1. Hathazari, Bangladesh, Jan-Apr 1988. Eight fertilizer levels were tested (Table Treatment Paniclesa Filled 1,000-grain Grain 2) in a randomized complete block design (kg NPK/ha) (no./m 2 ) spikelets weight Yield (no./panicle) (g) (t/ha) with four replications. All the P and K, and 1/3 the N were 0-0-0 186.30 45.21 21.15 1.4 applied basally after final land preparation. 0-28-34 213.97 51.09 22.55 2.1 The remaining N was topdressed, 1/3 at 25 40-28-34 244.89 63.12 23.03 3.0 d after transplanting (DT) and 1/3 at 45 80-28-0 266.62 72.12 23.09 3.7 DT. Purbachi rice seedlings (35 d old) 80-28-17 276.07 77.67 23.32 4.1 were transplanted at 25- × 15-cm spacing. 80-28-34 277.42 77.84 23.44 4.1 77.14 23.60 4.2 Application of 120 kg N, 34 kg K/ha gave 80-28-51 274.72 120-28-34 308.47 76.67 24.76 4.4 the highest yield. No significant yield differences were found when K was CV (%) 12.44 11.44 2.05 7.3 applied at 17-51 kg/ha with 80-120 kg N/ LSD (0.01) 63.74 15.49 0.50 0.5 ha (Table 2). The relatively low effect of K a on grain yield may be attributed to the From urea, triple superphosphate, and muriate of potash. increased K content of the surface silts.

Response of rice to Response of White Ponni rice grown in organically and chemically fertilized fields. a Pondicherry, India Azospirillum brasilense and Sep 1988-Feb 1989. organic manures on organic- and chemical-fertilized farms Grain yield (t/ha) Straw yield (t/ha) Treatment in India Gloria Farmer’s Gloria Farmer’s Land field Land field R. Subramanian and M. Rangarajan, Agricul- - No addition 5.7 8.1 - tural Microbiology Department, Tamil Nadu 100 N-50 P-50 N - 5.1 - 7.4 Agricultural University, Coimbatore 641003, Farmyard manure (FYM) 5.9 4.4 8.8 6.9 Tamil Nadu, India (3.15) (7.5) Green leaf manure (GLM) 6.7 4.1 9.9 6.5 (17.7) (21.9) Field trials were conducted in lowland Cow dung slurry (CS) 6.1 4.0 8.7 6.4 rice culture during Sep 1988-Feb 1989 on (6.1) (7.1) two farms in Pondicherry, India, using Azospirillum 5.9 4.1 7.5 6.5 (2.6) White Ponni rice variety. One farm FYM + Azospirillum 6.2 5.1 8.8 7.0 (Gloria Land) had adopted organic (9.1 ) (1.2) (8.2) farming 10 yr before. The other farm GLM + Azospirillum 6.8 4.9 9.8 6.9 (18.2) (19.8) (farmer’s field) had for several years used CS + Azospirillum 6.2 4.9 9.8 6.4 only chemical fertilizers. (8.6) (20.5) The field trials were laid out in a FYM + GLM + CS + Azospirillum 6.8 5.7 10.4 7.6 (19.2) (13.3) (28.3) (3.7) randomized block design with nine LSD 0.4 0.2 1.7 0.5 treatments and four replications. The a control plots on the two farms differed; Figures in parentheses indicate percentage increase. the farmer’s field plot received 100:50:50 kg NPK/ha. Other treatments included effect on yield of different organic higher grain yield than N fertilizer alone. farmyard manure (12.5 t/ha), leaves of manures with or without Azospirillum In Gloria Land, where organic manures Azadirachta indica (6.25 t/ha), and cow brasilense varied, depending upon the N had been applied for several years, Azos- dung slurry (5.0 t/ha) alone and in content of the organic manures. In the pirillum application did not have a signifi- combination with A. brasilense (seed, farmer’s field, N fertilizer yielded less cant effect. In the farmer’s field, Azos- seedling, and soil application). than the control plot of Gloria Land. pirillum application increased grain yield Grain yield in Gloria Land increased Combined application of organic manures significantly. Straw yields followed a with some treatments (see table). The plus A. brasilense gave significantly similar trend.

Surveys of disease or insect incidence/severity in one environment are useful only if the information is related to other variables (e.g., climatic factors, crop intensification, cultivars, management practices, etc.). By itself, information on incidence in one environment does not increase scientific knowledge.

IRRN 15:3 (June 1990) 27 We evaluated the traditional method However, the pretransplanting differ- Crop management against improved methods of raising ences did not significantly affect crop seedlings in two consecutive experiments yields. Seedlings from the traditional Effect of traditional and im- during 1988 wet season. Treatments nursery were not superior to seedlings proved nursery methods on included preburning of nursery bed and from improved nurseries. seedling growth and rice raised and flat nursery beds with various Thus, the traditional method benefits yield mechanical and herbicidal weed control only the nursery and should be discour- treatments (see table). aged to save valuable organic matter and M. V. Zagade, S. A. Khanvilkar, and B. P. The experiment was laid out in a vegetation. Instead, herbicides should be Patil, Agronomy Department, Konkan Krishi randomized block design with three used to control weeds in the nursery. Vidyapeeth, Dapoli 415712, Dist. Ratnagiri replications. Soil of the experimental plot (MS), India was lateritic having 152.5, 6.9, and 248.9 kg available N, P, K/ha. Plot sizes were 6 Integrated pest In the Konkan region of Maharashtra, rice × 1 m for the nursery and 4.6 × 4.2 m for management–diseases seedlings traditionally are raised on a flat transplanting. Nursery area burning was nursery bed on which a large quantity of done in May 1988 and Ratnagiri 24 was cow dung, twigs of trees ( Terminalia planted in Jun 1988. Preemergence Nonfluorescent spp.), dry grass, and dry leaves of forest herbicides were applied on wet soil. Pseudomonas strains trees have been burned. To further Seedlings from the set of nursery causing rice sterility and increase soil temperature, burning is treatments were transplanted in a grain discoloration slowed by spreading a thin layer of fine different field in a randomized block in Colombia soil on top of the organic matter. design with three replications. Recom- Each year, branches of forest trees and mended plant population (20 × 15 cm), R. S. Ziegler and E. Alvarez, Rice Program, bushes are cut to collect organic matter. fertilizers (100 kg N, 22 kg P/ha), and Centro Internacional de Agricultura Tropical That eventually depletes the forests and plant protection measures were applied (CIAT), Apartado Aereo 6713, Cali, Colombia degrades the soils. In the summer, uniformly to all treatments. skeletons of Terminalia trees and burned Seedling height and dry matter in the Two nonfluorescent species of Pseudo- patches of fields are common sights. traditional rice nursery were more than monas, P. avenae and P. glumae, cause Weed control seems to be the only twice that in the other nursery treatments seedling rot, grain discoloration (GlD), objective of this traditional method. (see table). This could be attributed to and sterility in rice. P. avenae is known Although the seedlings raised are vigor- increased availability of N (l0%), P to be distributed worldwide; until a recent ous, long-term detrimental effects do not (39%), and K (100%). Also, all weeds report from Latin America, P. glumae warrant the short-term advantages. were eliminated. was known only in Asia. Reports on the

Effect of preburning nursery bed and raised and flat bed nurseries with different weed control methods on seedling growth and transplanted rice yield. a

Seedling Dry matter/ D ry weight Weed control Available Available Exchangeable Grain Straw Treatment height seedling of weeds efficiency N P K yield yield (cm) (mg) (t/ha) (%) (kg/ha) (kg/ha) (kg/ha) (t/ha) (t/ha)

Rabbing (preburning) 10.5 115.0 - 100 168.7 9.9 439.1 2.4 3.0 Raised bed + unweeded control 5.8 42.0 1.2 13.3 152.7 6.8 233.8 2.4 2.8 Raised bed + weed-free check 6.3 47.3 0.3 75.9 153.5 7.1 224.0 2.8 3.2 Flat bed + unweeded control 5.7 40.0 1.4 0.0 156.1 6.9 237.2 2.3 2.8 Flat bed + weed-free check 6.0 46.3 0.3 75.9 150.3 7.2 237.2 2.8 3.1 Raised bed +one hand weeding 5.8 49.3 0.3 76.3 153.1 7.0 240.5 2.8 3.0 Flat bed + one hand weeding 5.7 46.3 0.3 75.9 152.6 6.9 233.1 2.3 2.8 Raised bed + 3.0 kg ai butachlor 5.3 34.6 0.2 85.1 146.1 7.0 238.7 2.2 2.6 50 EC/ha at preemergence Flat bed + 3.0 kg ai butachlor 5.5 36.0 0.2 84.7 146.1 7.1 241.8 2.1 2.8 50 EC/ha at preemergence Raised bed + 3.0 kg ai butachlor 4.9 33.6 0.2 85.1 144.9 6.9 234.4 2.3 2.7 10% G/ha at preemergence Flat bed + 3.0 kg ai butachlor 5.7 38.0 0.2 84.7 151.4 6.9 238.8 2.2 2.7 10% G/ha at preemergence Raised bed + l.0 kg ai oxadiazon/ha 4.9 37.0 0.2 85.5 151.4 7.0 229.2 24 2.8 at preemergence Flat bed + l.0 kg ai oxadiazon/ha 5.9 41.0 0.2 85.1 154.3 6.9 237.3 2.5 2.9 at preemergence LSD (0.05) 1.1 9.9 0.1 6.5 0.6 25.4 ns ns a Nursery variables measured at time of uprooting seedlings.

28 IRRN 15:3 (June 1990) characteristics of these species differ. We The pathogenic strains recovered from all strains. The growth limit for P. glumae undertook to more completely character- discolored grains were consistent with P. has been reported to be 40 °C; however, strains reported as P. glumae found in glumae, rather than with P. avenae (see the strains in this study all grew at 41°C. Latin America. We also compared the table). All strains tested could be distin- Researchers in the U.S., in establishing characteristics of the two species to guished from Erwinia herbicola in that the synonymy of P. alboprecipitans and clarify some discrepancies in published they did not grow anaerobically and had P. setaria with P. avenae ( P. menae is descriptions. multiple polar flagella. However, some now considered to be the correct name far Three strains of a nonfluorescent differences were observed among the this pathogen), described their strains as pathogenic bacterium obtained from field-collected strains and the strains of oxidase negative. More recently, re- discolored rice grains collected from known identity, as well as differences searchers in Japan described their strains farmers’ fields in Colombia were from published characteristics of the as oxidase positive. We have found our compared with four culture collection species. strains to be oxidase positive. strains of P. glumae and 25 strains of P. The original description of P. glumae The Japanese researchers also reported avenae (6 culture collection strains and referred to it as producing a fluorescent that their strains grew in 3% NaCl but not 19 strains previously identified at CIAT), pigment on potato agar. This probably in 5% NaCl. Our strains grew in 5% using standard bacteriological techniques. referred to the diffusible green nonfluo- NaCl. The Japanese reported negative The culture collection strains included rescent pigment that we and others have tobacco hypersensitivity, lipase, and H2S type specimens of each species. observed to be produced by some, but not production. Our strains were positive, negative, and variable, respectively. The strains we identified as P. avenae and P. Phenotypic characteristics a three Pseudomonas strains that cause grain discoloration and sterility in Colombian ricefields compared to strains of P. glumae and P. avenae. glumae also abundantly accumulated poly-b-hydroxybutyrate crystals. P. glumae Colombian strain P. avenae Phenotypic character (4 strains) (25 strains) 1445-4-1 1445-4-2 1462-7-2 False smut incidence on rice Fluorescent pigment - - - - - relative to plant characters Arginine dihydrolase and environmental factors Nitrate reduction - + + + + Oxidase - - - - + Diffusible green pigment d (50) + + - - C. L. Bhardwaj, Regional Research Station, Accumulation of poly-b- + + + + + Himachal Pradesh Krishi Vishvavidyalaya, hydroxybutyrate crystals Bajaura (Kullu)-175125, India Utilization for growth Arabinose + + + + d (60) We studied false smut Ustilaginoidea Cellobiose + + + + - virens Tak. incidence on 32 rice cultivars Raffinose + + + + - Sucrose - - - - - and the relationship of disease severity to Xylose d (75) + + + + plant characters and ambient environ- Adonitol + + + + - mental factors in the 1987 dry season. Inositol + + + + - Rice cultivars were dry seeded in upland Sorbitol d (75) - - - + Arginine d (75) + + + - conditions, in a completely randomized Salicine + + + + - block design with three replications. Acid from False smut of panicles at maturity was Dextrose d (75) + + + + recorded for each cultivar. Disease Lactose - - - - - severity, infected panicles, and number of Sucrose - - - - - infected florets on the most infected Mannitol + + + + d (76) panicle were recorded. H 2 S from TSI - - - - d (76) B3719C-TB-8-1-4, China 988, Catalase d (75) + + + + Gelatin liquefaction d (50) + + + - HPU2202, HPU5101, Nag 1-38, VL 501, Growth at 41°C + + + + + and VRS1 were disease free. Disease Growth in 5% NaCl + + + + + severity on the 26 susceptible cultivars Indole - - - - - Lecithinase + + + + - ranged from 1 to 17.9%. A significant Levan from sucrose - - - - - negative correlation ( r = -0.54) Lipase - - - - - between plant height (range 70-135 cm) Pit formation on CVP - - - - - Starch hydrolysis - - - - + and disease severity indicated that short Tobacco hypersensitivty + + + + + cultivars were more vulnerable than tall Pathogenicity on rice + + + + + ones. a + = 90% or more of strains positive, - = 90% or more of strains negative, d = 11-89% strains positive; number in parentheses is The correlation of disease severity and percent of strains positive. days to 50% flowering was not signifi-

IRRN 15:3 (June 1990) 29 Linear correlations of false smut ( Ustilaginoidea Laboratory examination revealed the icity test to fulfill the requirements of virens ) disease incidence (percent panicles with false smut) on 32 rice cultivars and plant and presence of Fusarium moniliforme Koch’s postulates confirmed F. monili- environmental factors. Sheld., the imperfect stage of Gibberella forme to be the causal organism. fijikuroi (identified on the basis of micro This is the first report of this disease Correlation coefficient and macro conidia, micro conidiophores, in Pakistan. ( r ) a and micro conidial chains). A pathogen-

Plant Plant height (cm) -0.54* cide similar to synthetic pyrethroids) Days to 50% flowering 0.095** Efficacy of ethofenprox in preventing rice tungro (RTV) against GLH and RTV transmission. a Environment Potted TN1 plants in controlled Maximum temp d (28.1°C) -0.048 infection Minimum temp (20.1°C) -0.040 greenhouse conditions were sprayed with Relative humidity (87.8%) -0.321 N. V. Krishnaiah and A. Ghosh, Directorate ethofenprox. At 0.01%, ethofenprox Rainfall (1.4 mm) -0.120 of Rice Research, Rajendranagar, Hyderabad killed 78% of confined viruliferous adults Cloudiness (1.74 h) -0.176 500030, India within 30 min; plants sprayed with 0.01% Disease severity recorded significantly lower RTV Number of false-smutted florets 0.81* RTV transmitted by green leafhopper infection than plants sprayed with 0.05% on the panicle with maximum infection (GLH) Nephotettix virescens is one of the monocrotophos (see table). GLH mortal- important diseases of rice in many parts ity within 30 min and RTV transmission a b P (0.05) = 0349*. Av of 32 d during flowering. of India. We studied the efficacy of were related; GLH mortality after 30 min ethofenprox (a new ether-derived insecti- was not related to RTV transmission. cant. Correlations with environmental factors during flowering (22 Aug-29 Sep) Effect of ethofenprox and monocrotophos on green leafhoppers and RTV transmission. a were negative and nonsignificant (see GLH mortality (%) RTV table). Insecticide infection Among cultivars, the positive correla- 0.5 h 1.0 h 4.0 h 24 h (%) tion ( r = 0.81) of number of smutted Ethofenprox 0.01% 78 a 87 a 95 a 100 a 53 a florets on the panicle with the most Monocrotophos 0.05% 22 b 58 a 93 a 100 a 80 b infected florets and percent false smutted Untreated control 0 c 0 b 0 b 2 b 100 c panicles was significant. The relationship a In a column, means followed by the same letter are not significantly different at the 5% level by DMRT. between number of smutted florets on the panicle with the most infected florets and percent panicles with false smut (regres- Integrated pest management–insects sion coefficient y = 1.26 + 0.763 x ) shows that, in assessing disease severity, one disease severity factor can be used to Mutual interference among spiders. Freshly emerged BPH adult estimate another factor. wolf spider adult females females were placed inside mylar cages (19-cm diam, 55-cm ht) with 5 tillers of K. L. Heong and E. G. Rubia, Entomology TN1 potted rice plants at densities of 5, Department, IRRI 10, 20, 30, and 60 BPH/cage. They were Bakanae and foot rot of rice exposed to 1, 2, or 3 freshly emerged in Punjab, Pakistan In ricefields, wolf spiders Lycosa adult female wolf spiders for 24 h. There pseudoannulata respond to high densities were 5 replications. L. K. Khokhar, National Agricultural of prey, particularly brown planthopper Searching efficiency per spider, a, Research Centre, Crop Diseases Research (BPH) Nilaparvata lugens (Stål). This over the experimental period was Institute, Islamabad, Pakistan increases the chances that spiders will computed as encounter each other while hunting for a = 1 /P 1n [ N /( N-N )] During a 1989 survey of rice crop prey. That may decrease searching a where a is searching efficiency, P is diseases in Sialkot, Gujranwala, and efficiency per predator and increase a predator number, N is initial number of Sheikhupura of Punjab Province, Basmati tendency toward aggression, cannibalism, 385 growing in isolated farmers’ fields and outward dispersal. Such encounters BPH, and N a is number of BPH attacked showed symptoms similar to those of between searching predators are often Log of a was plotted against log of P to bakanae disease. Some of the plants had called “mutual interference.” obtain a linear regression. The resulting yellowish green, thin leaves and exhib- We conducted laboratory experiments relationship of this linear mode1 is ited abnormal stem elongation, lower to measure mutual interference among log a = log Q - m log P tillering, and rotting at the root-stem joint wolf spiders and to determine the effect where Q and m are constants, characteris- as well as at the first node. of hopper density on encounters between tic of the predator.

30 IRRN 15:3 (June 1990) Regression analysis of the linear model log a = log Q - m log P in different prey densities. Toxicity of insecticides to Parameter estimate a mirid bug predator of rice PH density brown planthopper m + s.e. log Q F P 5 0.439 ± 0.283 0.322 2.40 0.14* P. R. Srinivas and I. C. Pasalu, Entomology 10 0.556 ± 0.243 0.268 5.23 0.03* Department, Directorate of Rice Research, ns 20 0.103 ± 0.206 0.25 1 0.25 0.63 Rajendranagar, Hyderabad 500030, A.P., 30 0.486 ± 0.191 0.242 6.46 0.02* India 60 0.707 ± 0.122 0.288 33.63 <0.01** a ns = not significant, * = significant at p = 0.05, ** = significant at p = 0.01. We tested 10 selected commercial formu- For BPH densities of 5 and 20, the aggregate at higher hopper densities lations in the glasshouse for their toxicity regression was not significant It was increasing the chances of encountering to the predator Cyrtorhinus lividipennis significant for BPH densities of 10, 30, each other. At low hopper densities, the (Reuter). Insecticide formulations were and 60 (see table). Mutual interference spiders disperse to about one spider/plant, prepared with distilled water and sprayed appears to intensify with increase in prey and there is less chance that spiders will (using a fine atomizer) to the runoff stage density. The m values for BPH densities encounter each other. on potted 30-d-old TN1 plants. Control of 10 and 30 were not significant, but m We observed some cannibalism, espe- was distilled water only. Adult mirid was significantly large for the BPH cially in cages with three spiders. bugs (30/treatment) were caged on the density of 60. This means that the spiders plants 4 h after spraying and mortality recorded 18 h later. Synthetic pyrethroids cypermethrin, peak was Oct-Dec: moths caught per Fluctuation of yellow stem fluvalinate, and fenvalerate were highly standard week ranged from 9 to 1,015 in borer (YSB) populations in toxic to the mirid bug (LC values of 1987 and 4 to 559 moths in 1988. 50 Raichur, Karnataka, India 0.00036, 0.0045, and 0.0053, respec- The second peak was Mar-May: moths tively) (see table). Quinalphos also was caught ranged from 4 to 82 in 1988 and B. S. Nandihalli, B. V. Patil, and P. Hugar, toxic (0.008 LC ). The insecticides 26 to 1,042 in 1989. The insect was 50 Entomology Department, University of methomyl and ethofenfox were relatively Agricultural Sciences, Raichur 584101, inactive Jun-Sep both years. More moths safe (LC values of 0.024 and 0.041, Karnataka, India were caught Mar-May 1989 because 50 respectively). The remaining insecticides canal water supply for the rice crop was exhibited moderate toxicity. We used a modified Robinson model low and most farmers did not apply plant light trap with 160-W mercury lamp protection measures. 1987-88 and 1988-89 to generate infor- These findings suggest that YSB Toxicity of insecticides (LC 50 values) to mirid bug. mation on population fluctuations of YSB counts to evaluate the need for crop Insecticide LC 50 Range Scirpophaga incertulas (Walker) to use in protection measures should be made in the integrated pest management program. the field the first week of Oct for wet Cypermethrin 0.00036*** 0.00039-0.00017 Fenvalerate 0.0053** 0.007 -0.004 Two peak activity periods were ob- season and during the first week of Mar Fluvalinate 0.0045** 0.006 -0.0033 served both years (see figure). The first for summer crops. BPMC 0.0073** 0.0094 -0.0057 Quinalphos 0.008** 0.010 -0.006 Chlorpyrifos 0.0095** 0.012 -0.008 Furathiocarb 0.01 17** 0.0152 -0.0091 Monocrotophos 0.0129** 0.0163 -0.0102 Methomyl 0.024* 0.0299 -0.0194 Ethofenprox 0.0406* 0.0456 -0.036

a * = log * 10 3 ; ** = log * l0 4 ; *** = log * 10 5

Feeding and food assimilation by two species of rice leaffolders (LF) on selected weed plants

M. L. P. Abenes and Z. R. Khan, IRRI-ICIPE Project, IRRI

Several weed plants present in the ricefields are reported to be alternate hosts for Population fluctuation of YSB Scirpophaga incertulas (Walker). Karnataka, India, 1987-89. rice LF. We studied the feeding rates and

IRRN 15:3 (June 1990) 31 food assimilation of Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae) on 12 selected weed plants collected from ricefields and multiplied in the greenhouse. The weed plants were Brachiaria mutica, Digitaria ciliaris, Dactyloctenium aegyptium, Echinochloa glabrescens. E. crus-galli, E. colona, Eleusine indica, Leptochloa chinensis, Leersia hexandra, Paspalum distichum, Panicum repens, and Paspalum conjugatum. Third-instar larvae were starved but water satiated for 2 h and weighed individually (W 1 ). Leafcuts of weed plant, susceptible IR36, or resistant TKM6 rice Leaf area consumption and food assimilation by third-instar larvae of C. medinalis and M. patnalis (30- to 35-d-old) were offered in a no- on graminaceous weed plants and rice hosts. choice test to individual LF larvae for 24 h. Larval weight (W 2 ) was recorded 2 h the other weed plants tested was signifi- ties and significantly lower on L. hexan- after the end of the feeding period. The cantly lower. dra and L. chinensis. There was either setup was replicated 10 times. Food assimilation by M. patnalis very low or no food assimilation on the Leaf area consumed was measured larvae was highest on the two rice varie- other weeds. using a leaf area meter. Food assimilation was computed: Mass rearing of a mirid several 30-d-old TN1 rice plants infested with five gravid BPH females (see Food assimilation = W 1 ( C 1 - C 2 ) + ( W 2 - W 1 ) predator C 1 figure). Plants, mirids, and BPH females I. Manti, Sukarami Research Institute for Food are transferred into the oviposition cage where W and W are initial and final 1 2 Crops (SARIF), P.O. Box 34 Padang, West Plants are transferred to emerging cage weights of test insects and C 1 and C 2 Sumatra, Indonesia and B. M. Shepard, IRRI after 24 h. The door and top of the 45- × initial and final weights of control insects. 55- × 60-cm cage are made of glass; the C. medinalis larvae fed most on D. Mirid predator Cyrtorhinus lividipennis three other sides, of fine nylon mesh. ciliaris, followed by E. glabrescens, P. Reuter can be mass-reared on brown When the mirid eggs hatch, some conjugatum, and E. indica (see figure). planthopper (BPH) eggs, using TN1 rice gravid BPH females are added to provide Feeding on susceptible IR36 was lower plants. food for the mirids. Each cage will pro- than on D. ciliaris but comparable to Adult mirids collected in the field are duce mirids of known age, which can be feeding on TKM6, E. colona, E. crus- introduced into mylar cages containing used for experiments. galli, L. chinensis, L. hexandra, and P. distichum. Feeding on B. mutica and P. repens was significantly lower than on either rice varieties as well as on most of the weeds tested. Food assimilation by C. medinalis was highest on P. conjugatum, followed by E. glabrescens, D. ciliaris, D. aegyptium, and L. hexandra. Food assimilation on E. indica, E. crus-galli, P. distichum, and E. colona was similar to that on both susceptible IR36 and resistant TKM6. Food assimilation on P. repens was significantly lower than on the rice varieties and most of the weeds tested. M. patnalis larvae fed most on susceptible IR36 and resistant TKM6. Feeding on L. hexandra and L. chinensis was comparable to feeding on IR36. Feeding on Procedure for mass-rearing C. lividipennis. DAI = days after mirid introduction.

32 IRRN 15:3 (June 1990) In preemergence treatments, thioben- Integrated pest management–weeds carb (1.0 kg ai/ha) with one hand weeding resulted in the best weed kill and Weed control in dry and wet dicots (46%); in wet seeded rice, mono- in per-hectare yields of 4.9 t dry seeded rice and 4.6 t wet seeded rice (see table). seeded irrigated rice cots predominated (79%). Irrespective of season, Echinochloa colona was the Butachlor (1.5 kg ai/ha) with one hand O. S. Kandasamy and SP. Palaniappan, Tamil major grass species; Cyperus rotundus, weeding, and two hand weedings alone Nadu Agricultural University, Coimbatore the major sedge. Ludwigia adscendens were equally effective. In postemergence 641003. India was the major broadleaf. Marsilea treatments, no herbicide was effective in quadrifolia (a fern) was also important. either dry or wet seeded rice. We evaluated 12 weed control treatments involving five herbicides applied Effect of weed control and seeding method on grain yield and weed weight in direct seeded rice. Aduthurai, preemergence and followed by (fb) hand India. weeding (HW) and applied early poste- Grain yield (t/ha) Weed weight (t/ha) mergence in combination with 2,4-D; and Rate two hand weedings during Jun-Sep Treatment (kg ai/ha) Dry Wet Dry Wet seeded seeded seeded seeded (kuruvai) and Oct-Feb (thaladi) at Aduthurai. In Jun, dry seeds of TKM9 Unweeded control - 2.4 2.7 2.4 1.7 (110 d duration) were sown on dry field; Two hand weedings (15 & 30 DAS) - 4.5 4.6 0.4 0.4 in Oct, sprouted seeds of IR20 (130 d Preemergence duration) were sown on a puddled field. Thiobencarb fb HW 1.0 4.9 4.6 0.4 0.4 Butachlor fb HW 1.5 4.6 4.5 0.5 0.5 The trial was laid out in a randomized Fluchloralin fb HW 1.0 4.2 4.5 0.5 0.5 block design with three replications. Pendimethalin fb HW 1.5 4.2 4.2 0.7 0.5 Soil was clay loam. Preemergence Piperophos fb HW 1.5 4.0 4.0 0.8 0.6 herbicides were applied 5 d after seeding Early postemergence (DAS), early postemergence herbicides Thiobencarb + 2.4-D 1.0 + 1.0 3.9 3.8 0.9 0.6 3.6 4.0 0.6 were applied 15 DAS. Plots treated with Butachlor + 2,4-D 1.5 + 1.0 0.9 Fluchloralin + 2,4-D 1.0 + 1.0 3.5 3.9 0.9 0.7 preemergence herbicides were hand Pendimethalin + 2.4-D 1.5 + 1.0 3.5 3.9 0.9 0.7 weeded at 30 DAS. Plots with two hand Piperophos + 2.4-D 1.5 + 1.0 3.2 3.4 1.0 0.7 weedings were weeded 15 and 30 DAS. LSD (0.05) for all plots, pre- 0.1 0.6 0.1 0.1 emergence and postemergence At 60 DAS , weed flora in dry seeded LSD (0.05) between pre- 0.1 0.3 0.1 0.1 rice consisted of monocots (54%) and emergence and postemergence

Effect of time and number of Effect of hand weeding on grain yield, straw yield, weed dry weight, and control efficiency in direct seeded weedings on direct seeded rainfed rice at Jagdalpur, Madhya Pradesh, India, 1985-86. upland rice yields Grain Straw Weed Weed control J. R. Patel, Indira Gandhi Agricultural Treatment yield yield dry weight efficiency University, Sub-Research Centre, Bangoli, (t/ha) (t/ha) (t/ha) (%) Raipur, Madhya Pradesh 493225, India No weeding 0.2 0.5 2.8 - One hand weeding 20 DAS 0.9 1.6 1.2 48.0 In Bastar, India, 50% of the cultivable One hand weeding 40 DAS 1.2 2.1 1.7 57.3 One hand weeding 60 DAS 0.7 1.5 2.1 40.3 land, more than 40,000 ha, is upland, One hand weeding 80 DAS 0.4 1.1 1.0 29.3 cultivated primarily by tribal farmers. Two hand weedings 20 & 40 DAS 1.4 2.4 1.0 64.0 Three hand weedings 20, 40, & 2.0 3.5 0.7 75.3 Mean annual rainfall ranges from 1200 to 60 DAS 1600 mm. Southeast monsoon rains start Four hand weedings 20, 40, 2.3 3.9 0.3 80.0 in June and the rice crop is harvested at 60, & 80 DAS the end of the rainy season. LSD (0.05) 0.3 0.5 0.4 - CV (%) 12.2 10.2 11.8 - Direct seeding is the preferred rice crop establishment method, and hand weeding is the only method of weed control. With no weed control, yield was significantly. Straw yield, weed dry We evaluated eight weed control significantly lower (see table). When weight, and weed control efficiency methods during 1985-86 wet season in a weeding was delayed, yield decreased showed similar trends. randomized block design with three proportionately, to the lowest with one At least two weedings at 20 and 40 d replications. Widely grown rice variety weeding 80 d after seeding (DAS). after emergence are needed to protect Culture 1 (90-95 d duration) was used. Weeding more than once improved yield yield potential.

IRRN 15:3 (June 1990) 33 a Weed composition in dry First appearance and floristic composition of weeds in Orissa State, India. seeded wetland rice Weed composition b Botanical name First S. N. Jena, AICRIP Regional Research appearance 30 DARE At harvest (165 DARE) Station, Chiplima, Sambalpur, Orissa; and G. (DARE) K. Patro, AICARP, OUAT, Bhubaneswar, Plants/ % of Plants/ % of m 2 b population m 2 population Orissa, India Cynodon dactylon (L.) Pers. 15 10.80 1.49 33.60 4.24 A major constraint on rice yields in Echinochloa colona (L.) Link 15 145.60 20.17 76.80 9.69 Orissa State is high weed incidence. We Leptochloa chinensis (L.) Nees 15 32.20 4.46 21.20 2.67 Ischaemum rugosum Salisb. 30 27.20 3.77 27.20 3.43 identified the major weed flora and their Panicum repens L. 15 44.80 6.21 69.20 8.73 composition in rainfed lowland rice Cyperus iria L. 15 158.80 21.99 51.20 6.46 C. difformis L. during the 1987 wet season. All weeds in 30 37.60 5.21 40.40 5.10 C. rotundus L. 30 18.40 2.55 21.20 2.67 2 0.25-m samples from 12 wetland C. imbricatus Retz 30 9.60 1.33 24.00 3.03 ricefields (two samples/field), were Fimbristylis miliacea (L) Vahl 15 73.60 10.19 47.12 5.95 Scirpus acutus Muhl. identified and the weed species found in 30 20.00 2.77 32.00 4.04 S. articulatus L. 30 34.68 4.80 54.40 6.86 all samples counted. All fields had been Aeschynamene indica L. 15 10.40 1.44 22.80 2.88 dry seeded. Alternanthera sessilis (L.) R. Br. 30 6.80 0.94 17.32 2.19 Cyanotis cucullata Kunth Echinochloa colona was the dominant 15 32.00 4.43 78.80 9.94 Hedyotis corymbosa (L.) Lam. 75 - - 17.20 2.17 grassy weed found (see table). Sedges Ipomea aquatica Forssk 90 - - 20.72 2.61 Cyperus iria, C. difformis, Fimbristylis Limnophila indica (L.) Druce 30 6.80 0.94 12.00 1.51 Ludwigia parviflora (L.) Roxb. 30 22.72 3.15 50.40 6.36 miliacea, and Scirpus articulatus also had Marsilea quadrifolia L. 30 14.80 2.05 - - high incidence. Among the broadleaf Manachoria vaginalis (Burm. f.) Presl. 30 5.72 0.80 11.52 1.45 weeds, Cyanotis cucullata and Ludwigia Portulaca oleracea L. 120 - - 18.72 2.36 Sesbania exaltata (Raf.) Cory. parviflora were high. Ipomoea aquatica, 30 4.28 0.59 14.80 1.87 Sphenaclea zeylanica Gaertn. 30 5.20 0.72 30.00 3.79 Hedyotis corymbosa, and Portulaca Total 722.00 100.00 792.60 100.00 oleracea appeared at later crop growth stages. a DARE = days after rice emergence. b Av of 24 samples. Farming systems intercropped with black gram or soybean, irrigated twice with 10 cm water total. The in a randomized block design with four water table was 6.7 m deep during the Intercropping following rice replications. cropping period. S. Muralikrishnasamy, M. N. Budhar, R. Soil was clay (fine Udic Chromusterts) Yield of cotton in the paired row Rajendran, and A. A. Kareem, Tamil Nadu with CEC 35 meq/100 g soil, 0.5% intercrop with black gram equaled yield of Rice Research Institute (TRRI), Aduthurai, organic C, and 65% water-holding cotton as a pure crop (see table). Cotton + Tamil Nadu, India capacity. Spacing was 60 × 30 cm for black gram gave the highest net return. cotton and 30 × 10 cm for black gram and In the Cauvery Delta Zone, cotton soybean. In the intercrop treatments, two Gossypium hirsutum or black gram Vigna rows of cotton were sown at 45/75 × 30- Rice-based cropping mungo is grown in Jan-Feb following wet cm spacing and two rows of the intercrop systems for rainfed lowland season rice. We evaluated cotton MCU7, at 75- × 30-cm spacing. conditions soybean Glycine max (CO 1), and black Cotton was irrigated six times, with 30 gram (ADT4) as pure crops and cotton cm water total; the pulse crops were R. B. Thakur, Rajendra Agricultural Univer- sity, Bihar, Pusa 848125, India

Yield and net return of sole crops and intercrops in rice fallow system. TRRI, Aduthurai, Tamil Nadu, India, 1988. We studied the effect of seeding and fertilizer rates on the production potential a Yield (t/ha) Yield Cultivation Net of rice-based cropping systems under Treatment value b cost return Cotton Soybean Black gram ($/ha) ($/ha) ($/ha) rainfed lowland conditions in 1988-89. The soil was silty loam with pH 8.4, Cotton 1.1 - - 571 264 307 0.62% organic C, and 278-39.2-140.2 kg Soybean - 1.4 - 363 112 251 Black gram - - 1.3 625 131 494 available N, P 2 O5 , and K 2 O per hectare. Cotton + soybean 0.8 1.2 - 726 343 383 Radha rice (35-d-old seedlings) was Cotton + black gram 1.1 - 1.0 1052 336 716 transplanted 15 Jul and harvested 10 Dec LSD (P = 0.05) - - - - - 18 1988. Gram C235, linseed Subhra, and a Mean of 4 replications. b Cotton, $519/t; soybean, $259/t; black gram, $481/t. lentil Pant 406 were broadcast 25 Nov in

34 IRRN 15:3 (June 1990) the standing rice crop at two seeding rates Productivity of rice-based intercropping systems in Pusa, Bihar, India, 1988-89. (normal and 50% higher than normal) Grain yield (t/ha) with and without fertilizer. Fertilizer was Treatment broadcast 3 d before sowing the intercrop. Rice Intercrop Rice yield Equivalence The experiment was laid out in a randomized block design with four replications. Rice alone 3.7 - 3.7 Rice yield was 3.8 t/ha. Yields of Rice + gram, normal seeding rate. no fertilizer (S 1F 1) 3.7 0.1 4.1 Rice + gram, normal seeding rate. fertilized a (S F ) 3.7 0.2 4.2 gram, linseed, and lentil ranged from 0.12 1 2 Rice +gram + 150% seeding. no fertilizer (S 2F 1) 3.7 0.1 4.1 to 0.17, 0.45 to 0.68, and 0.16 to 0.29 t/ Rice + gram + 150% seeding, fertilized (S 2F 2) 3.8 0.2 4.2 ha, respectively. (Lower yields of gram Rice + linseed + S 1F 1 3.7 0.4 4.5 Rice + linseed + S F 3.7 0.6 4.9 and linseed were due to a winter drought.) 1 2 Rice + linseed + S 2F 1 3.7 0.6 4.8 Rice - linseed produced significantly Rice + linseed + S 2F 2 3.8 0.7 5.1 higher rice equivalency yield than rice - Rice + lentil + S 1F 1 3.7 0.2 4.3 Rice + lentil + S F 3.7 0.2 4.2 gram and rice - lentil (see table). Linseed 1 2 Rice + lentil + S 2F 1 3.6 0.2 4.2 with fertilizer yielded significantly higher Rice + lentil + S 2F 2 3.7 0.3 4.4 than other crops. The interaction between LSD (0.05) ns 0.1 0.4 crops and seeding rates was not a 20 kg N + 18 kg P/ha for gram and lentil, 30 kg N + 9 kg P/ha for linseed. significant.

Production potential and economics of upland rice + Yield and economics of rice + pigeonpea cropping system under different sowing methods and mixing proportions. a Orissa, India, 1985-87. pigeonpea Treatment S. S. Patra, Regional Research Station (RRS), Yield Gross return Profit Keonjhar 758002, Orissa, India Sowing Proportion (t/ha) ($/ha) ($/ha)

Rice 60% + 1.2 506.44 342.81 Upland rice + pigeonpea is the widely pigeonpea 40% 1.2 adopted mixed cropping system in Keonjhar. But grazing by stray cattle after Rice 70% + 1.5 463.38 297.38 Rice and pigeonpea pigeonpea 30% 1.0 rice harvest reduces pigeonpea yields. mixed and broadcast Pigeonpea remains in the field 2 mo Rice 80% + 1.6 444.88 276.56 longer, and farmers lose interest in pigeonpea 20% 0.9 protecting a thinly populated crop that Rice 60% (1.5 m broadcast 1.3 may not give an adequate return. Recom- sown) + 565.81 399.75 mended seeding rates for single crop rice pigeonpea 40% (2 rows 1.4 50 cm apart) and pigeonpea are 100 and 20 kg/ha, respectively. Rice broadcast Rice 70% (3.0 m broadcast 1.6 We evaluated proportions of rice and and pigeonpea sown) + 539.63 37 1.50 line dibbled 1.2 pigeonpea during 1985-87 wet season. pigeonpea 30% (2 rows 50 cm apart) The experiment was laid out in a randomized block design with three replications. Rice 80% (4.5 m broadcast 1.9 sown) + 494.75 323.94 Experimental crop schedules are given in pigeonpea 20% (2 rows 1.0 the table. 50 cm apart) Soil of the experimental site was sandy Rice 60% (10 rows 15 cm 1.5 with pH 5.7, low available N (242 kg/ha) apart) + 626.44 458.44 and P (8.0 kg/ha), and medium available pigeonpea 40% (2 rows 1.5 K (97.0 kg/ha). 50 cm apart) Rice cultivar Shankar (85 d duration) Rice and pigeonpea Rice 70% (20 rows 15 cm 1.6 and pigeonpea UPAS 120 (145 d) were line sown apart) + 599.31 418.69 sown 21 Jun 1985, 24 Jun 1986, and 27 pigeonpea 30% (2 rows 1.3 50 cm apart) Jun 1987. Fertilizer was 60-13-25 kg NPK/ha for rice and 20-17.4-0 kg NPK/ha Rice 80% (30 rows 2.1 for pigeonpea. 15 cm apart) + 563.00 391.63 pigeonpea 20% (2 rows 1.1 Line sowing 2 rows of pigeonpea 50 50 cm apart) cm apart after each 10 rows of rice 15 cm a apart gave the highest return. Av of 2 yr.

IRRN 15:3 (June 1990) 35 Rice-based intercropping Kalinga III rice was sown in 2:2 row Rice alone yielded 22 t/ha (see table). systems for rainfed upland ratio with ragi, 3:1 and 4:1 with red In the intercrops, highest rice yield was in conditions of Chotanagpur gram, and 2:1 with other crops. rice + red gram. Red gram produced the plateau The experiment was laid out in a highest yield among the intercrops. randomized block design with four Highest rice equivalent yield was with C. V. Singh, R. K. Singh, R. K. Tomar, V. S. replications. N was applied as basal to rice + red gram 4:1 ratio and lowest with Chauhan, and M. Variar, Central Rainfed pulses, at 20 kg N/ha. Rice was fertilized rice + cowpea 2:l ratio. All combinations Upland Rice Research Station, Hazaribag with 60 kg N and ragi with 40 kg N/ha. P were efficient, with land equivalency 825301, Bihar, India and K at 17 kg/ha were applied as basal ratios of more than one. Highest return to all crops. was with rice + red gram. In the upland area of Chotanagpur region (red lateritic, slopy), upland rice, ragi Yield of rice and intercrops in Hazaribag, India, 1988 wet season. (minor millet), and pulses are grown in Yield (t/ha) Rice Land rotation with 1 yr fallow. Intercropping Intercropping system equivalent Return equivalency pulses or millets with upland rice could Rice Intercrop yield (t/ha) ($/ha) ratio increase the cropping intensity of these Rice + green gram 1.2 0.2 1.9 312 1.20 areas. (2:1) Rice + black gram 1.3 0.2 1.9 321 1.27 We studied the feasibility of intercrop- (2:l) ping in red soils (pH 5.4, 0.39% organic Rice + red gram 1.4 0.4 2.5 418 1.32 C, and CEC 12.3 meg/100 g soil) during (3:1) Rice + red gram 1.6 0.4 2.6 438 1.36 1988 wet season. (4:l) Ragi (local), green gram (Sunayana), Rice + cowpea 0.9 0.3 1.7 289 1.12 black gram (T-9), cowpea (Gomati), and (2:1) rice + ragi 1.0 1.1 1.7 291 1.02 red gram (BR65) were sown at 20-, 20-, (2:2) 45-, 45-, and 75-cm row spacing, respec- Rice alone 2.2 2.2 368 1.00 tively, as sole crop and as intercrops. LSD (0.05) 0.2

Some transplanted rice- Fertilizer costs were highest ($247/ha) The difference between returns from based cropping systems in rice - potato - transplanted winter fertilizer and total productivity is ascribed maize and lowest in rice - peas - green to the higher fertilizer requirements of M. S. Sidhu, T. S. Sahota, B. D. Sharma, and gram ($126/ha). Fertilizer return was rice - potato - transplanted winter maize B. K. Dhaliwal, Agronomy Department, highest in rice - potato - sunflower and than in cropping systems involving Punjab Agricultural University, Ludhiana lowest in rice - wheat. legumes and oilseeds. 141004, India Production and returns from some rice-based cropping systems in Punjab, India, 1987-88. We evaluated some rice-based cropping Total Rice Cost of Gross returns ($) systems involving cereals other than rice, grain equivalent fertilizer legumes, oilseeds, and potato during Cropping system a yield yield ($/ha) Per Per $ 1987-88. The alluvial soil was calcare- (t/ha) (t/ha) ha fertilizer ous, sandy loam with pH 8.1 and 0.28% Rice - wheat 8.4 8.8 163 953 5.85 organic C. All crops received recom- (4.1) (4.3) mended fertilizer except sunflower Rice - winter maize 9.5 11.4 174 1229 7.06 (4.8) (4.7) following potato. Rice-peas-green gram 8.0 13.5 126 1462 11.61 Rice equivalent yield was highest with (4.9) (1.7) (1.4) rice - potato - transplanted winter maize Rice - Swede rape - green gram 8.0 14.2 148 1579 10.66 (27.4 t/ha), followed by rice - potato - (5.4) (1.4) (1.3) sunflower (21.8 t/ha) and rice - Indian Rice - potato - transplanted winter maize 12.0 27.4 247 2970 12.03 (5.6) (20.5) (6.4) +20.5b rape - transplanted Swede rape - green Rice - Indian rape - transplanted Swede rape 9.0 19.0 175 2052 11.73 gram (19 t/ha) (see table). Productivity of (4.8) (1.8) (0.8) rice - wheat, the dominant cropping sys- - green gram tem in northern India, was lowest (8.8 t/ (1.6) Rice - potato - sunflower 6.2 21.8 162 2362 14.58 ha). (4.9) (21.2) (1.3) +21.2 b Maximum gross return was $2,970/ha Rice - Indian rape - sunflower 8.4 15.0 138 1621 11.75 with rice - potato - transplanted winter (5.1) (1.9) (1.4) maize (more than 3 times the $953/ha a Figures in parentheses are yield (t/ha). In the first three systems, rice PR108 (145 d duration) was used; in the other systems, PRTB return with rice - wheat). (125 d duration) was used. b Potato tubers.

36 IRRN 15:3 (June 1990) Water requirement for peanut Water use, yield, and yield attributes of peanut following rice under different irrigation levels. following rice in Bangalore Irrigation level a LSD Character (0.05) T1 T3 T3 K. Joseph and G. V. Havanagi, Agronomy Department, University of Agricultural Plant height at 40.5 41.5 38.7 ns Sciences, Bangalore, India maturity (cm) Dry matter production at 9.3 10.2 9.9 ns harvest (g/plant) We studied the water requirement for Test weight (g/100 kernels) 28.9 28.7 28.9 ns 74.2 73.4 73.7 ns peanut in summer rice fallows 1983 and Shelling percentage Pod yield (t/ha) 2.2 2.2 2.1 ns 1984. One irrigation was given all treat- Water use efficiency 77.8 112.7 179.9 7.0 ments at planting. Treatments were Water use (cm) 28.8 17.2 8.9 - irrigation at 40% soil moisture deficit at a T1= at 40% soil moisture deficit; T2 = at flowering, pod formation, pod filling; T3 = at pod formation. 30-cm soil depth, at flowering, pod formation, and pod filling; and at pod Growth and yield attributes were additional irrigation (8.86 cm) only at formation. The water table receded from statistically similar (see table). Water use pod formation. 20.6 to 63.3 cm during the crop period. efficiency was significantly higher with

Rice variety to fit cropping Yield of rice cultivars to fit different cropping patterns In Tripura, India, 1982-84. patterns in Tripura, India Yield (t/ha) Variety Wet season Dry season S. K. Gupta and S. Laskar, ICAR Research Complex for N. E. H. Region, Tripura Centre, 1982 1983 Mean Productivity 1983 1984 Mean Productivity Lembucherra 799210, India (kg/d) (kg/d) Mahsuri 2.6 2.3 2.4 16.3 2.5 2.7 2.6 16.5 Rice variety Mahsuri is popular in Jaya 1.9 2.2 2.1 16.0 3..0 3.0 3.0 21.7 Tripura but its 150-d duration delays Vijaya 2.6 2.6 2.6 20.6 3.8 3.1 3.4 26.1 sowing of succeeding crops potato, CR75-93 2.6 2.6 2.6 20.6 3.9 4.5 4.2 31.2 (Saberi) wheat, or mustard and preceding crops IR36 2.2 2.5 2.4 19.6 3.7 3.4 3.5 27.6 jute and rice. LSD a (0.05) ns ns ns - 0.8 0.9 0.8 - We compared four 125-d duration rice a ns - not significant varieties with Mahsuri during 1982 and 1983 wet seasons and 1983 and 1984 dry seasons. The experiment was laid out in a meq/100 g soil. Thirty-day-old seedlings Grain yields in the dry season differed randomized block design with four repli- were transplanted at 20- × 15-cm spacing: significantly. Highest yield was with cations. fertilizer was 60-30-30 kg NPK/ha as Saberi (see table). Soil was loamy with pH 5.5,0.06% urea, single superphosphate, and muriate Yields in the wet season did not differ total N, 0.94% organic C, and CEC 9.97 of potash. significantly.

Relay cropping in upland rice and density had no significant effect on unusually lanky growth and poor stand, fallows relay crop yield. which could be due to low temperatures. Highest pulse yield was with lathyrus, Highest net profit was with bengal T. Barik and K. C. Sahoo, Regional Research and lowest was with black gram (see gram, followed by lathyrus. improved Station, Bhawanipatna, Kalahandi, Orissa table). Local field gram yielded higher pea, and local field pea. 766001, India than improved field pea. Black gram had

We evaluated the effect of rice varieties Yield and return from pulses grown as relay crops following rice. Orissa, India, 1985-86 to 1987-88. Jajati and Assamchudi at three densities Cost of Net with six pulses as relay crops 1985-86 to Crop Variety Yield cultivation profit/ha Duration 1987-88. The experiment was laid out in a (t/ha) ($) ($) (d) split-plot design with three replications. Bengal gram OG 62 0.21 32.85 59.12 109 Soil was medium black, clayey, with Lathyrus Local 0.22 21.90 41.75 104 Black gram T9 0.03 16.42 (-)7.23 92 medium fertility and pH 7.8. Lentil T397 0.10 21.90 13.87 107 Jajati rice yielded 0.2 t/ha more than Improved field pea Rachna 0.15 32.85 31.97 102 local variety Assamchudi. Rice variety Local field pea Local 0.19 27.37 27.52 101

IRRN 15:3 (June 1990) 37