Effect of Climate of Florida and Arizona on Grapefruit Fruit Enlargement and Quality; Apparent Transpiration and Internal Water Stress1

HILGEMAN: GRAPEFRUIT — CLIMATE STUDIES 99 couragement, observations and suggestions in 2. Steams, Charles R. Jr.,J. T. Griffiths, W. L. Thomp son, and E. J. Deszyck. Progress report on concentrated compiling and assembling data for this presenta sprays on citrus in Florida. Proceedings, Fla. State Hort. tion. Soc, 1951. 3. Steams, Charles R. Jr., W. L. Thompson, R. B. LITERATURE CITED Johnson, and E. J. Deszyck. Method of Applying insecti 1. Griffiths, James T., C. R. Steams, and W. L. Thomp cides with different spray machines. Proceedings, Fla. son. Possibilities for the use of concentrated sprays on State Hort. Soc, 1952. citrusin Florida. Proceedings, Fla. State Hort Soc, 1950.

EFFECT OF CLIMATE OF FLORIDA AND ARIZONA ON GRAPEFRUIT FRUIT ENLARGEMENT AND QUALITY; APPARENT TRANSPIRATION AND INTERNAL WATER STRESS1

r. h. hilgeman2 Introduction

'Valencia' oranges grown in Florida have a Abstract thinner peel and more juice but lower percen tages of acid and total soluble solids than Ari Fruit enlargement rates, changes in physical zona fruit (3). Similar differences in grape characteristics and water relationships were fol fruit are indicated by maturity studies (6) (8). lowed between July and November in Florida in These differences have been associated with the 1964 and in Arizona in 1965. widely different climatic conditions (3). How In Florida, due to summer rains and clouds, ever, detailed comparisons of the responses of relatively uniform fruit enlargement rates were trees to each environment have not been made, maintained. With soil water below 10 cbs. ten except with trunk growth of 'Valencia7 oranges sion, heavy rains increased enlargement rates (4). This investigation was designed to evaluate and intensified internal pressures on the peel. responses associated with typical commercial In Arizona, blossoming was 45 days later, fruit trees, grown with normal culture practices in was only % as large as Florida fruit on July 1 each area. It is recognized that differences in but grew more rapidly. Fruit enlargement rates soils, stocks and cultural practices, particularly varied widely between irrigations. Internal pres use of arsenical sprays, influence tree responses sure on the peel was low. and fruit characteristics, as wellas climate. In Florida, continuously high soil water and This report compares the effects of climatic low internal water deficits in July, August and conditions in the 2 areas on (A) fruit enlarge September apparently induced high juice con ment rates and physical and chemical character tent and thin peel. The high juice content re istics; (B) apparent transpiration from leaves sulted in lower solids and acid percentages than and internal water deficits. found in Arizona. On sunny Florida days, apparent transpira Materials and Methods tion was similar to Arizona, although atmos pheric vapor pressure deficits were about 3 times Five large, vigorous 'Redblush' grapefruit higher in Arizona; internal water deficits were trees on rough lemon stock, about 18 years old, markedly higher in Arizona. were selected in a commercial grove growing

lUniversity of Arizona Agricultural Experiment Sta on fine sand soil, about 11 miles south of Winter tion Journal Series paper No. 1173. Garden, Florida. Trees received adequate fer 2Horticulturist, University of Arizona Citrus Experi ment Station, Tempe, Arizona. The author was employed tilization and insect control and were sprayed as collaborator by the USDA, ARS Crops Research Division at Orlando, Florida, during 1964, while on Sabbatical leave. with arsenical materials. Irrigation was with 100 FLORIDA STATE HORTICULTURAL SOCIETY, 1966 perforated pipe sprinklers with most of the wa each area between July and November in 1964 ter falling in alternate rows. No "off-season" in Florida and 1965 in Arizona. fruit was present; twig growth occurred irreg Maximum and minimum temperatures were ularly during the summer. obtained in U. S. Weather Bureau shelters, lo Four moderately vigorous 'Marsh' grapefruit cated about 5 miles from the trees in Florida trees on sour orange stock of similar size, but and about 100 yards from them in Arizona. In 33 years old, were selected at the University of Florida, the accumulative precipitation between Arizona Citrus Experiment Station, near Phoe fruit measurement intervals was measured at nix, Arizona. The trees were growing in calcare the test trees. In Arizona, precipitation was ous, gravelly, sandy loam, soil moderatly fertil measured daily at the thermometer station. ized with nitrogen, clean cultivated, and irri Irrigations are indicated in Figure 1. About gated by flooding between borders under the 2 to 3 inches of water were applied in Florida. tree. No "off season" bloom occurred and sum In Arizona, 5 to 6 inches were applied to either mer growth was light. one side or to the entire soil area as indicated Similar observations were made on trees in in Figure 1. Tensiometers were placed at 18

400 .FRUIT ENLARGEMENT

DAILY ENLARGEMENT RATE A PRECIPITATION

Florida

.£ t(M\ o

DAILY TRUNK SHRINKAGE Florida

Fig. 1.—Seasonal growth of fruit, daily fruit enlargement rates, and trunk shrinkage as affected by precipitation and irrigation in Florida in 1964 and Arizona in 1965. HILGEMAN: GRAPEFRUIT — CLIMATE STUDIES 101 and 30 inch depth at the drip of the trees. weighed within 15 seconds after removal from Fruit Enlargement and Characteristics; Trunk the tree and after 2 minutes exposure at its Measurements. Forty fruits were measured near original place on the tree. Loss of water is sunrise at 2 to 5 day intervals as shown in Fig reported as mg of water/g fresh wt./hr. The ure 1. Circumference measurements were con leaf petiole was then placed in water, transfer verted to volume, according to tables of Taylor red to a saturated atmosphere and weighed 26 and Furr (15). Fruit shrinkage during the day to 32 hours later. The percentage water de was reported as percent of volume loss based on ficit was calculated by dividing the gain in volume near sunrise. Fritts dendographs were weight by the hydrated leaf weight. In Arizona, placed on trunks of two trees in a previously observations were started near sunrise. In Flor described manner (4) to obtain daily records of ida, they were delayed from 1 to 3 hours later trunk shrinkage. until the dew had evaporated. Wet and dry Five fruits per tree were collected on dates bulb temperatures were obtained from sling shown in Table 2. Fruit was weighed, volume psychrometers at intervals during the day. determined by water displacement and specific gravity calculated. Juice was extracted with a Results and Discussion Sunkist extractor, pressed through cheesecloth and weighed. Total soluble solids were meas Climatic Conditions. The mean monthly temper ured as sucrose with an Abbe refractometer. atures and total precipitation set forth in Table Acid was determined by titration with standard 1 show Florida rainfall was near normal in July alkali. and August. The hurricane caused 9.73 inches Apparent Transpiration and Internal Water between September 8 to 13. No rain fell between Stress. Apparent transpiration was estimated October 14 and November 27. The normal Ari by methods used by Oppenheimer and Mendel zona mean temperatures in July and August (12). Spring flush leaves weighing between 1.0 were associated with maximum and minimum and 1.5 g were used in both areas. A leaf was temperatures about 2° F above and below nor-

Table 1, Temperature and precipitation in Florida and Arizona

July Aug. Sept. Oct. Nov. Florida 1964 Mean max. F. 90 91 tib1 81 78 Mean min. °F. 72 73 71 63 60 Departure from 0 0 + 1 - 2 + 3 normal a/ °F. Total precip. in. 3.22 c/ 7.67 ll.ij.7 .65 1.08 Days with precip• 9 19 10 k 1 Departure from + .71 + k.2k - 3.31 - .k9 normal a/ in. Arizona 1965 Mean max. °F. 107 107 9« 77 Mean mino °F. 72 69 61 Departure from 0 0 - k + 2 + k normal b/ °F. Total precip • in. .36 .81 .51 .I4.O 1.36 Days with precip. 2 1 3 Departure from J - -U5 - .10 - .20 + .70 normal b/in.

Departure of mean temperature and precipitation from normal at: a/ Orlando, Florida; b/ Tempe, Arizona. 0/ Precipitation at test grove between July 17 and 31. 102 FLORIDA STATE HORTICULTURAL SOCIETY, 1966 mal. In September, minimum temperatures were largement rates dropped rapidly, although a below 50° F on 4 days (low 45° F). Rainfall light rain and a drop in temperature occurred was well below normal until late November and soil water was available. Internal pressures when 1.28 inches fell on November 23 and 25. sufficient to cause contraction of the peel upon cutting did not develop at any time. Part. 1. Fruit Enlargement, Trunk Shrinkage, Daily Trunk Shrinkage. The trunk shrinks or Fruit Quality expands during the day as the internal water FRUIT ENLARGEMENT. Full bloom was supply changes (4) (10). Figure 1 shows the about March 1 in Florida and April 15 in Ari amount of daily diameter shrinkage. zona. Fruit enlargement rates and daily shrink Florida. Rain and cloudy days retarded age changed with age so the 45 day age differ shrinkage on about 50 percent of the days be ence induced differences in these values on the tween July 17 and September 22. On days with same dates (Fig. 1). Enlargement of similar age heavy, almost continuous rainfall, almost none fruit was about equal; however, the absolute ocurred (July 26; Sept. 9, 10, 11 and 15). Dur values for fruit size are not basic to this study. ing sunny days without rain, large shrinkage Florida. Between July 17 and Oct. 9 rela took place. tively uniform gradually decreasing daily During the dry October-November drouth growth rates were maintained by rainfall dur period, daily shrinkage was more uniform with ing each measurement interval. Although soil losses from .005 to .011 inches. As the soil be water tensions were below 10 cbs., rain increased came dry, increased shrinkage did not occur. enlargement rates during measurement periods Irrigation did not affect shrinkage, possibly prior to July 27, August 3 and September 11. because only part of the soil was wet. The 2 successive high rain periods in Sep- Arizona. Between July 3 and Sept. 23 shrink ember produced different responses. The Septem age followed typical patterns (10). After irri ber 8 to 11 period (6.00 inches rain) increased gation, shrinkage was reduced to .003 to .007 enlargement to 3.05 cc/day; whereas during inch and gradually increased to .012 and to .015 the September 11 to 14 period (3.73 inches rain), inch as the soil became drier. Rainfall retarded the rate was reduced to 1.04 cc/day. Apparently shrinkage on only 2 days. An unexplained re the fruit was fully hydrated after the first rain duction in shrinkage, which was different from and a continuation of the high rate of enlarge that observed on 'Valencia' orange trunks (10), ment was not possible. Extremely high internal started after the September 24 irrigation. pressure developed in the fruit. Cutting the peel Changes in fruit characteristics. In both cases, from stem to blossom end on one side was im peel thickness began to decrease markedly after mediately followed by a contraction of the peel fruit was about 130 days old and continued un and enlargement of the segments producing a til about 230 days old (Table 2). With fruit of 4 to 6 mm opening of the cut. similiar volume, minimum peel thickness and By October 12, low rainfall had reduced soil maximum specific gravity was about 5.5 mm and water unevenly to tensions of 40 to 70 cb. and .85, respectively, in Florida, and 8.6 mm and fruit enlargement stopped. After a rapid in .77 in Arizona. The ratio of length/ diameter crease, following a .35 inch rain, it shrank prior did not change appreciably in Florida and grad to October 19. The October 19 irrigation im ually decreased until September in Arizona. mediately increased rate of enlargement to 1.7 In Florida, juice content did not change af cc/day. This was followed by a gradual de ter it attained 55% in whole fruit when 233 crease to .8 cc/day, prior to the November 18 days old. In Arizona, juice content was still irrigation which was not required. increasing when testing was discontinued on Arizona. Daily enlargement rates followed 223 day old fruit. typical patterns associated with irrigated oranges in the desert (9). Each irrigation in Total soluble solids ranged from 8.2 to 8.7% duced hydration of fruit and a high rate of in Florida fruit and did not change significantly; enlargement which was followed by successively in Arizona, an increase from 10.9 to 11.5% lower rates. This was correlated with soil water occurred. In fruit about 220 days old, acid had tensions which increased from 10 cb. at 30 inch decreased to 1.18% in Florida and to 1.97% in depth after irrigation to 45 to 60 cbs. just prior Arizona. to irrigations. Between September 6 and 24, en In Arizona, the average values obtained from HILGEMAN:GRAPEFRUIT — CLIMATE STUDIES 108

Table2 - Changesin physicaland chemical characteristics of grapefruit

Vol. Leng. Spec. Juicea/ Total Solid Age fruit diara.grav. Peel peel- soluble Total acid Date fruit tested ratio fruit thick whole ed solids acid ratio (days) (cc) (mm) {%) ) (g)b/(%) (g)b/ Florida 196lJ

7/10 132 I8I4. .92 .71 11.3 - 7/2k llj.6 231 .73 9.7 8/3 156 253 o91 .76 8o5 177 305 .92 .78 7.7 9/8 192 307 o90 .82 6.6 9/21 348 .92 .82 6.6 205 hi 68 8.1* 11.1 1.31 Io7l|6.1| 10/6 220 37U .90 .82 6.1 51 71 8.6 13.5 1.18 1.85 7^3 376 .90 55 10/19233 «85 5.6 73 8.7 111.8 1.152.02 7.6 10/3021* 385 .89 08I1. 5.5 392 .90 5.6 11/9 251| .85 54 73 8.2 111..8 l.llj. 2.05 7.2 Arizona 1965 7/2 78 57 1.00 .76 13.0

7/22 98 ll^l 1oOO .68 13.0 8/9 116 189 .97 .68 12.0 8/23 130 239 .95 .69 12.2 9/15 153 282 .93 o73 9.8 9/23 161 302 .93 .73 32 9.3 1C.9 7.7 2.08 1.1+35o2 10/8 176 9.2 30 11.2 3l|-l|.93 .75 lj-8 9.6 2.06 1.75 5.1+ 10/22190 367 .91+ .76 8.7 37 59 11.0 11.k 2.02 2o08 54 11/5 20lj. 371 .77 8.3 38 60 11.2 12.2 1.99 2.16 5.6 66 223 1^26 .76 8.6 5.8 .9U k3 11.If 15.9 1.97 2.7lj-

25 grovesin mid-October during the past 11 albedoenlarged and juicesacs remained small. yearsand in 1965,were, respectively, as fol Nearthe end of this period, the specific gravity lowstotal soluble solids 10.9 and 10.7%;acid andpeel thickness offruit were similar inFlor

1.81and 1.97%;juice peeled in fruit 61 and ida(July 10) and Arizona (August 23).

55%;peel thickness 9.6and 9.3 mm. Solidsand Duringthe following 80 to 100 days,the acidin Octoberwere higher than the average fruitgrowth rate gradually declined, juice sacs

SaltRiver Valley grapefruit in 1965. In 1965 enlargedand filled and peel thickness decreased. grapefruitmatured later than in any other Climaticconditions inFlorida and Arizona dur year. ingthis interval appeared to produce the large

A comparisonof the Floridavalues with differencesin juice content and peelthickness. thoseobtained by Deszyckand Sites(5) on 8 In Florida,because of the early blossoming, the to 10 yearold trees, shows solids and acids enlargementand hydrationof juicesacs coin weremoderately lower and juice percentage con cidedwith the Julyto Septemberwarm tem siderablyhigher than their 3 yearaverage, but peraturesand highrainfall. Continuously high almostidentical with 1 year.It appears that soilwater and relativelylow internalwater thevalues were reasonably typical of Floridadeficits on about half of the daysapparently

'Redblush'grapefruit and thatin 1964 juice augmentedcell hydration and enlargementof contentwas aboveaverage and the percentagejuice sacs. The rapidlyexpanding sacs exerted solidsbelow average. pressureon thealbedo, stretching the cells to

producethe ' thin peel. In Arizona,the later

DISCUSSION. Observationson physical and bloomingdelayed this stage to lateAugust, chemicalcharacteristics weremade duringthe Septemberand October,when moderatelyhigh periodof rapidgrowth when thecells in the daytemperatures, coolnights and little rainfall albedowere enlarging and stretchingand juice occurred.Internal water deficits andlack of hyd

sacsenlarging and filling,designated develop rationof the treeapparently prevented full mentstage 2 by Bain(1). During the first 130 hydrationof juicesacs and consequentdevelop daysof this period, fruit growth was rapid,the mentof pressureon thealbedo. 104 FLORIDA STATE HORTICULTURAL SOCIETY, 1966

FLORIDA-JULY 30,1964 ARIZONA-JULY 21, APPARENT TRANSPIRATION

APPARENT LEAF WATER DEFICIT

Shad*

TRUNK A FRUIT SHRINKAGE

TEMPERATURE & VAPOR

Fig. 2. Changes during typical summer days in apparent transpiration rates and leaf water deficits in spring flush leaves, trunk and fruit shrinkage in relation to temperature and vapor pressure deficit.

A comparison of total soluble solids and In fruit 205 days old, there was 2.16 g acid between the areas is complicated by the acid/fruit in Arizona and 1.74 g acid/fruit in following factors present in Florida; (A) high Florida. This approximate 20% reduction in soil water which reduces the percent of solids Florida could be accounted for by the arsenate (14); (B) rough lemon stock which reduces sprays which have reduced acid from 7 to 14% solids and acid below sour orange stock (2); (5) (6) and rough lemon stock which has in (C) lead arsenate spray which reduces acid duced a 7 to 9% (2) (5) reduction. Corrections (5). However, the major factor is dilution of for these two factors would equalize approxi the solids by the larger amount of juice in the mately the total acid content per fruit. juice sacks. The percentage juice in the whole

fruit does not completely reflect this condition Part II. Apparent Transpiration and Internal because of the effect of different amounts of Water Deficits peel. The different peel thickness also induces an error in calculating total solids per fruit Apparent transpiration on July days in in fruit of equal size. Florida and Arizona under conditions of high Table 2, however, indicates that fruit of rea soil water in both areas following a generally sonably similar age and size in each area con similar pattern (Fig. 2). Water loss from leaves tained about the same amount of solids per fruit. was low early in the morning, increased rapidly HILGEMAN: GRAPEFRUIT — CLIMATE STUDIES 105 to maximum levels near noon and remained Similar observations were obtained on the high during the afternoon. Leaves exposed to same trees on 6 other days (Fig. 3). The sum full sun lost water more rapidly than shaded marized data show generally similar relation leaves. Accompanying this increase in rate of ships existed until November with the excep leaf water loss was an increase in the apparent tion of fruit shrinkage. As fruit became more water deficit in the leaves. Sun leaves had mature less shrinkage occurred. In Florida, rain larger deficits than shade leaves. Deficits were interrupted measurements on July 22, July 30 greater in Arizona. Fruit shrinkage gradually and October 1, resulting in abrupt increases in increased during the day to a maximum at 4:00 trunk diameter. On October 1 heavy clouds re P.M. Greater shrinkage and consequent stress duced afternoon transpiration before the rain. on fruit occurred in Arizona. Trunk shrinkage During drouth in October in Florida, trunk followed the general pattern of fruit shrinkage shrinkage was large but fruit shrinkage was and was larger in Florida. In Arizona, a 105° low. High internal fruit pressures were main F temperature and 20% relative humidity pro tained, which apparently reflected a different duced vapor pressure deficits about 3 times physiological response of older fruit. greater than the 91° F temperature and 56% In Arizona, low soil water on July 14 and relative humidity in Florida. possibly on September 21 apparently reduced

FLORIDA ARIZONA

1\ A r & A n fi r\ 3o.l 7 0> <\ r • nt Laal W TT

* 6 * 10 pf —• 2 § * ■<* \ Shnn V V/t : 1AU1MJ ratu 7

Vapor )bt UJL ; 40 - ' 30 .

i msion a 15 to 39 5 to 69 29 te 70 60 20 50 I 7/19 I 7/22 I 7/30 I 9/11 I 10/1 10/23 9/2 I 1/19 | 9/21 9729

Figr. 3.—Average apparent transpiration rates and leaf water deficits in sun and shade leaves, fruit and trunk shrink age, in relation to air temperatures and vapor pressure deficits on 7 days between July and November. 106 FLORIDA STATE HORTICULTURAL SOCIETY, 1966 transpiration and induced higher leaf water ida. The author wishes to acknowledge the deficits, fruit and trunk shrinkage. technical assistance of Mr. Floyd Sharp, re DISCUSSION. The high apparent transpira search associate, and Mr. John Morrison, stu tion in Florida appeared to be induced by the dent laboratory assistant. following conditions; (A) full hydration of the leaves and wood by heavy dew and rainfall; LITERATURE CITED

(B) the very high soil water level; (C) rough 1. Bain, Joan M., 1957. Morphological, anatomical, and lemon stock which increases transpiration (13). physiological changes in the developing fruit of the Valen cia orange. Citrus sinensis (L) Osbeck. Aust. Jour, of Under full sun, water was lost very rapidly. Bot. 6:1: 1-24. However, a larger root and/or conduction sys 2. Cohen, Mortimer, and Herman J. Reitz, 1964. Root- stocks for Valencia oranges and Ruby Red grapefruit— tem or a larger internal water reserve prevented Results of a trial initiated at Fort Pierce in 1950 on two soil types. Proc. Fla. Sta. Hort. Sci. 76: development of high deficits in leaves and fruit. 3. Cooper, W. C, Ascension Peynado, J. R. Furr, Rob In Arizona, approximately equal transpira ert H. Hilgeman, G. A. Cahoon, and S. B. Boswell, 1962. Tree growth and fruit quality of Valencia oranges in tion but greater leaf water deficits and fruit relation to climate. Proc. Amer. Soc. Hort. Sci. 82: 180- 192. shrinkage accompanied the much higher poten 4. Cooper, W. C, R. H. Hilgeman, and G. K. Rasmussen, tial transpiration conditions. This situation in 1964. Diurnal and seasonal fluctuations of trunk growth of the Valencia orange as related to climate. Proc. Fla. dicates the following conditions were involved: Sta. Hort. Soc. 77: 101-106. 5. Deszyck, E. J. and J. W. Sites, 1954. The effect of (I) the root system and/or the water conduc lead arsenate sprays on quality and maturity of Ruby Red tion capacity limited the amount of water to grapefruit. Proc. Fla. Sta. Hort. Soc. 67. 38-42. 6. Harding, Paul L., and D. F. Fisher, 1945. Seasonal leaves; (2) high leaf water deficits induced changes in Florida grapefruit. U.S.D.A. Tech. Bui. No. partial closing of stomates which limited tran 886. 7. Harris, Karl, A. F. Kinnison, and D. W. Albert, spiration; (3) the extreme day stress and dry 1936. Use of water by Washington Navel oranges and Marsh grapefruit trees in Salt River Valley, Arizona. Univ. nights prevented full hydration of the tree at of Ariz. Agri. Expt. Sta. Bui. No. 153. night; (4) relatively low soil water. 8. Hilgeman, R. H., 1941. Studies of the ripening of Marsh grapefruit in Arizona. Univ. of Ariz. Agri. Expt. The data indicate that on sunny days, tran Sta. Bui. No. 89. 9. Hilgeman, R. H., Henry Tucker and Thomas A. spiration rates of leaves in Florida and Arizona Hales, 1959. The effect of temperature, precipitation, are not greatly different. Evapotranspiration blossom date and yield upon the enlargement of Valencia oranges. Proc. Amer. Soc. Hort. Sci. 74: 266-279. studies, based on changes in soil water, confirm 10. Hilgeman, Robert H., 1963. Trunk growth of the this. Water usage in July, August and Septem Valencia orange in relation to soil moisture and climate. Proc. Amer. Soc. Horti. Sci. 82: 193-198. ber are reported to be 13.5 inches in Florida 11. Koo, R. C. J. and J. W. Sites, 1955. Results of research and response of citrus to supplemental irrigation. (II) and 15.2 inches in Arizona (7). Soil Sci. Soc. of Fla. 15: 180-190. 12. Oppenheimer, H. R., and K. Mendel, 1939. Orange leaf transpiration under orchard conditions. Agri. Res. Sta., Acknowledgement Rehovot, Israel, Bui. No. 25. 13. Ongun, A. R., and A. Wallace, 1958. Transpiration rates of small Washington Navel trees grown in a glass Appreciation is extended to Dr. W. C. Cooper house with different rootstocks and at different root tem peratures. Tree Physiology Studies at U.C.L.A. 1: 87- and Dr. P. L. Harding and members of their 103. staff whose fine cooperation and assistance made 14. Sites, John W., Herman J. Reitz, and E. J. Deszyck, 1951. Some results of irrigation research with Florida this study possible. The author wishes to thank citrus. Proc. Fla. Sta. Hort. Sci. 64: 71-79. Mr. Avery Clements, production manager and 15. Taylor, C. A., and J. R. Furr, 1937. Use of soil- moisture and fruit-growth records for checking irrigation the owners of the Irrgang grove for their coop practices in citrus orchards. U.S.D.A. Circular No. 426. eration in providing trees for the test in Flor

INDUCED ANAEROBIOSIS CAUSED BY FLOOD IRRIGATION WITH WATER CONTAINING SULFIDES

H. W. Ford and D. V. Calvert2 Abstract

A grove in St. Lucie County, that had shown

l Florida Agricultural Experiment Stations Journal Ser poor growth for many years, was evaluated for ies No. 2509. the possibility that sulfides in the irrigation wa 2Horticulturist, University of Florida, Citrus Experi ment Station, Lake Alfred, and Assistant Soils Chemist, ter were damaging citrus roots. Roots extended University of Florida, Indian River Field Laboratory, only to a depth of 10 inches, which was the Fort Pierce.