Q .1 5-11 13 August 1971 Irrigation Spacing Blossom- End Rot ‘lemme AIM University, The Texas Agricultural Experiment Station, l-l. O. Kunkel, Acting Director, College Station, Texas [Blank Page in Original Bulletin] CONTENTS Summary ..................................... -. 4 Introduction .................................................................... .- 5 Methods and Procedures .............................................. .. 6 Location and Soils ................................................ .. 6 Irrigation Treatments .- ......... -- 6 Medium-Textured Soils ................................ -- 6 Fine-Textured Soils ....................................... _. 7 Water Requirement .............................................. -. 7 Blossom-End Rot-. .. ..... .. 8 Results and Discussion ................................................. -- 9 Irrigation Treatments ........................................... .. 9 Medium-Textured Soils ................................ .. 9 Fine-Textured Soils .... -.l0 Water Requirement -. 1O Medium-Textured Soils ................................ -_10 Fine-Textured Soils l3 Blossom-End Rot "-13 Literature Cited .... .. 19 3 SUMMARY Irrigation management studies for tomato pro- duction were conducted on medium- and fine-textured soils from 1958 through 1969. Medium-textured (La- redo and Willacy series) soils were excellent for the growth and production of tomatoes. Although yields varied with years and varieties, from l0 to more than 20 tons per acre of pear tomatoes were produced. Tomatoes which were thinned to 2 inches apart produced significantly less than tomatoes which were 6 to 12 inches apart. Irrigation treatments on medium-textured soils failed to increase yields in 4 of 6 years. However, a preplanting irrigation and an irrigation at bloom stage in dry years were needed to supply the l0 to 12 inches of water required to produce satisfactory yields. Root distribution and moisture use data indicate max- imum use of soil moisture on medium-textured soils is from the top 2 feet, but plants are able to extract significant water to a depth of 4 feet. Fine-textured (Harlingen series) soils were gen- erally unfavorable for tomato production. Maximum yields of pear tomatoes in the spring on Harlingen clay soils were low-ranging from 4 to l0 tons per acre. In 1967 fall Chico tomatoes produced slightly over l0 tons per acre. Tomatoes usually required an irrigation at planting time and three to four irriga- tions beginning at bloom stage (12-15 inches of water). Irrigations should be about l5 days apart during the blooming and fruiting time; there is danger of apply- ing too much water during this stage of plant growth. On these soils tomatoes are easily killed under con- ditions of poor aeration. Root distribution and mois- ture use by tomatoes are mostly in the top foot, but plants are able to extract water to a depth of 3 feet. However, extraction from the 3-foot depth is not suf- ficient to prevent great reductions in growth and yield. 4 From the relationship between incid Q som-end rot (BER) and moisture stress, mined that spring-grown pear tomatoes irrigated 7 to l5 days after initiation of to keep BER incidence below 5 percent , textured soils. In contrast, spring-grown toes on Harlingen clay soils had high BE even under high soil moisture conditio’ good part of the production occurred evaporative conditions. Low yields and incidence on pear tomatoes are two recommending these soils for tomato i However, fall-planted pear tomatoes on. soils had lower BER incidence and " ment. Since spring production of pear L ally means high incidence of BER, on '-: toes probably should be restricted to fall I The incidence of blossom-end rot on’ Chico Grande tomatoes seems to be highl ll climatic stress. Chemical analyses show especially the distal end, to be low in 1 and to have a high K:Ca ratio. High - decreases the movement of Ca into I transpiration increases the movement of *1 fruit. These data suggest that the leaves; indirectly deprive the fruit of the ml water and Ca which moves through the " f trability evaluation and transpiration v- the high permeability of small Chico- Grande tomato fruit. Diffusion pressure‘ 3 uations indicate that small fruit lose or F water in solutions of osmotic pressure. atmospheres. The high transpiration from and the slow movement of water into create a condition whereby water loss ~ n exceed water intake. Under high eva tions, transpiration losses from small _ cause collapse of the sensitive, unstable t“ result in blossom-end rot. __ _ \_ hjz": k j." .1.j; . I ,_ . ATOES Irrigation Spacing Blossom-End Rot C. J. Gerard, B. W. Hipp ond W. R. Cow|ey* trademark or a proprietary product does not con- I - tee or warranty of the product by The Texas j periment Station and does not imply its ap- p" exclusion of other products that may also be HE NUMBER OF ACRES IN TOMATO PRODUCTION in the Lower Rio Grande Valley has varied from year to year depending upon factors such as anticipated supply and demand for Valley tomatoes, supply of irrigation water and increasing production costs. However, the release of improved tomato varieties by Leeper (17) (18) (19) provided needed stimulus to the tomato industry. The importance of determining the most effi- cient use of a limited water supply for tomato production was responsible for the initiation of irri- gation management studies in 1958. Studies were con- ducted on green-wrap tomato varieties, Rio Grande and Homestead, 1958-60, and on processing varieties, Chico, 1962-64 and 1966-68, Chico Grande in 1965 and Chico III in 1969. The investigations with pear tomatoes revealed a need for determining the cause of blossom-end rot of pear tomatoes. Blossom-end rot (BER) is described as a physiological disorder of tomatoes. According to Geraldson (6), Spurr (22), Evans and Troxler (5) and Maynard et al. (20), BER first becomes apparent as a water-soaked area under the fruit wall on the blos- som-end of the fruit. This area subsequently develops into a blackened, dry, sunken spot. Geraldson (7) reported that excessive soluble NH4, K, Mg, Na and salts or a deficiency of soluble Ca increased BER incidence. Spurr (22) postulated that of the two principal causes of BER, moisture stress and calcium deficiency, the latter is the more - basic. Recently Wiersum (24, 25, 26) developed an explanation that mass flow transport in the phloem supplies the necessary water and most nutrients to the fruit but does not provide adequate Ca. He pointed out that the Ca content of such fruit, particularly in the storage tissue, is extremely low and, as a result, local disorders may occur. He cited data to show that during rapid growth very little, if any, water and Ca enter the tomato fruit. Gerard and Cowley (10) reported that such factors as growth rate, N ferti- lization and Ca content significantly influence cell permeability and osmotic pressure of fruit and, consequently, BER incidence. In addition, it was hypothesized that the primary cause of BER in pear- shaped tomatoes was the loss of water from the blos- som-end of fruit during its active growth stage and that BER probably results from transfer of water from fruit through transpiration to atmosphere and perhaps to other p-lant parts. Carolus et al. (3) also proposed that under climatic stress and low available soil moisture water may be withdrawn from fruit to such an extent that BER develops. The objectives of these studies generally were (1) to evaluate the influence of irrigation and spac- ing treatments on yield and quality, (2) to determine ‘Respectively, associate professor, associate professor, and resi- dent director of research and professor, Texas A8cM University Agricultural Research and Extension Center at Weslaco, Wes- laco, Texas. 5 the water requirement for optimum and economical production and (3) to determine the cause of blossom- end rot (BER) of pear tomatoes. METHODS AND PROCEDURES Location and Soils Laredo Series: Irrigation studies in 1958 were conducted on Laredo clay loam soil 2 miles south- east of Progreso, Texas, near the Rio Grande River. Many soils near the Rio Grande River, including the site near Progreso, are extremely variable. Although classified as Laredo clay loam, certain areas in the experimental site probably could be classified as Cameron clay loam. The clay loam surface, which varies in depth from 2 to 5 feet, is underlain by sand usually at depths of 2 to 3 feet but varies from 1 to 5 feet at this location. The Laredo soil has slow surface but excellent internal drainage and poten- tiality to hold a moderate to good reserve of soil moisture. The Cameron soils, in contrast, have poor surface and internal drainage. Willacy Series: Irrigation-spacing experiments were conducted on Willacy loam soil at the Texas A8cM University Agricultural Research and Exten- sion Center at Weslaco from 1959 through 1964. The Willacy loam is a deep, medium-textured, mod- erately permeable soil. Moderate to good drainage and a deep clay loam subsoil enable this soil to hold a good reserve of soil moisture. The typ-ical chemical properties of Willacy loam soil are shown in Table. l. Harlingen Series: The influences of moisture levels and other factors on tomato production and BER on Harlingen clay were investigated from 1965 through 1969. This location is about 2 miles north of Progreso, Texas. The Harlingen clay soils exhibit high swelling and shrinkage, severe cracking when dry and very poor surface and internal drainage. The sand, silt and clay contents are relatively con- stant to a depth of 5 feet. Chemical properties of Harlingen clay are reported in Table 1. Irrigation Treatments Medium-Textured Soils Laredo Series: An irrigation experiment in 1958 consisted of three moisture levels replicated four times. Irrigation treatments (Table 2) were based on available moisture content of the top 3 feet. Home- stead (green-wrap variety) tomatoes were planted on TABLE 1. CHEMICAL CHARACTERISTICS OF WILLACY LOAM AND HARLINGEN CLAY SOIL Meq/100 g Soil K Ca Mg Na pH Willacy loam 0.9 16.0 3.2 0.4 7.8 Harlingen clay 1.4 34.0 9.0 3.5 8.2 6 TABLE 2. IRRIGATION TREATMENTS ON LAREDO CLAY‘: AND WILLACY LOAM, 1959 ,__ Perc Available moisture moisllrlur.’ Irrigation in top 2 or 3 feet a o treatment at time of irrigation 1958 " Wet 60% 20.3 Medium 40% ’. 17.6 Dry 20% Al; 15.5 76-inch beds in January 1958. Tomatoes g to 12 inches between plants in March. were uniformly fertilized with 60 pounds I per acre. After maturation of fruit, green? toes were harvested weekly and graded quality. " Willacy Series: In 1959 a similar._._l using the green-wrap variety Rio 7 conducted. ' ‘ Other experiments were conducted in 1963 and 1964 on Willacy loam soils using? described in Table 3. Plots were 38 50 feet long in experimental designs of blocks consisting of four replications. W’; ments, initiated at bloom stage, were available moisture remaining in the u. soil. Rio Grande tomatoes which were 76-inch beds were lost due to frost in plants (Homestead variety) were planted apart in March and irrigated. Tomat’ vested weekly and graded as to size and ‘I TABLE 3. IRRIGATION AND SPACING TREATMENTSI LOAM, 1960, 1962, 1963 AND 1964 l i. ,. Available moisture . . . Percentage of I remaining m top at maximum all Irrigation 2 feet at time treatment of irrigation‘ 1960 1962 Wet 60% 15.5 16.3 Medium 40 % 14.0 14.2 Dry 20% 12.4 12.1 Very dry 0 10.8 10.0 Not irrigated Spacing treatment no. 1962 (Subplots) 1 Single row on top of 38-inch - I were spaced 12 inches apart. I’ 2 Double row (12 inches apart) on beds. Plants were 12 inches -, companion rows were staggered.‘ 1963 and 1964 I Plants were spaced 2 inches beds. 2 Plants were spaced 6 inches beds. ‘I 3 Plants were spaced 12 inches beds. i ‘Irrigation treatments were initiated after appearance) zStaggered means that plants on one row on top of 7 were spaced between plants on the other row. I .,- ‘ ‘a l" STURE LEVEL TREATMENTS ON HARLINGEN CLAY V‘! l gltttolsture treatmentl Yea rs evaluated " stage, tomatoes in all mois- y were to be irrigated when the l of the top 2 ft of soil was % of the available moisture. ts B, C, D and E were initi- I bloom stage. was applied after the bloom T965 T966 T967 I brought to field capacity the \ of soil when the average ‘A . content of the top 2 ft (“1- 50% of the available l T965 T966 V brought to field capacity the "ift of soil when the average l content of the top 2 ft i -- 25% of the available T965 T966 T967 _ brought to field capacity s5 ft of soil when the average content of the top 2 ft 0% of’ the available T965 T966 T967 I according to treatm-ent C. if er application by sprinkler every day during high evap- jfconditions I 967 p, Qols received a preplanting irrigation and were irri- sis of changes in average available moisture of the ;leld capacity is approximately equal to 31% soil osphere tension is approximately equal to 21% a processing tomato, was planted in jan- 3 and 1964. The main plots were split ("pacing treatments (Table 3) which were March. In 1962, plants were spaced 'art on single rows 0n 38-inch beds and .*rows on 76-inch beds. Plants on com- on 76-inch beds were staggered. The Brows were l2 inches apart. In 1963 and W plants were spaced 2, 6 and 12 inches p, inch beds as indicated in Table 3. Plot guniformly fertilized with 60 pounds of acre. When necessary, tomatoes were J recommended insecticides. Chico toma- l, ested 2 or 3 times to obtain yield esti- uenced by treatments. - Soils Huences of moisture level treatments on k1 tomatoes on Harlingen clay were evalu- p965 through 1969. The treatments, which omized blocks or Latin square designs, years. Moisture level treatments in 1965- _ 'bed in Table 4. Moisture treatments " 75 feet square. These treatments were fertility treatments in 1965 as shown treatment E (Table 4) consisted of three cs 100 feet long with a sprinkler posi- l0 feet. Light sprinkler applications were applied twice a day for 20 to 30 minutes except on Saturday and Sunday when only one application was made. In 1968 and 1969 the influences of treat- ments F and G (Table 6) were determined. Unlike treatment E in 1967, treatment G in 1968 and 1969 consisted of applying 0.1 inch of water to the plant canopy every other day. On Harlingen clay tomatoes were generally planted in mid-February and harvested in June or early July. Tomatoes were sprayed for insects with recommended chemicals. In fall 1966 a moisture level-row spacing-fertility management study was conducted on Harlingen clay (Table 7). Chico tomatoes were planted July 20 and irrigated July 23. Yield data were obtained in December 1966. Chico tomatoes grown under differ- ent broadcasted and banded P and Ca treatments (Table 8) were evaluated as to yields in 1967. ‘Water Requirement From 1958 to 1969 the time to irrigate the dif- ferent treatments was determined by evaluating soil moisture by 1-foot increments to a depth of 5 feet. Soil moisture was determined periodically from 1958 TABLE 5. MOISTURE LEVEL AND AMENDMENT TREATMENTS ON HARLINGEN CLAY SOIL, ‘I965 Percent of moisture at maximum allowable stress Soil moisture (main treatments)‘ Before the bloom stage, tomatoes in all mois- ture treatments were to be irrigated when the moisture content of the top 2 feet of soil was depleted to 25% of the available moisture. Moisture treatments B, C and D were initi- ated after the bloom stage. A. No water was applied after the bloom stage. B. Irrigation brought to field capacity the top 5 ft of soil when the average moisture content of the top 2 ft approached 50% of the available moisture 25 C. Irrigation brought to field capacity the top 5 ft of soil when the average moisture content of the top 2 ft approached 25% of the available moisture 23 D. Irrigation brought to field capacity the top 5 ft of soil when the average moisture content of the top 2 feet approached 0% of the available moisture 21 Nitrogen treatments, pounds nitrogen Amendment treatments per acre I. Check O 2. 2,000 lb per acre gypsum I00 3. 2,000 lb per acre sulfur 200 300 ‘All moisture levels received a preplanting irrigation and were irri- gated on the basis of changes in average available moisture of the top 2 feet under all spacing treatments. Field capacity is approxi- mately 31 percent; 15-atmosphere tension is approximately 21 percent. 7 TABLE 6. MOISTURE LEVELS, TRANSPIRATION SUPPRESSANTS AND SPRINKLER IRRIGATION TREATMENTS ON TOMATOES ON HARLINGEN CLAY, 1968 AND 1969 Percent of moisture at maximum Treatments allowable stress Before the bloom stage, tomatoes in all treatments were irrigated when the moisture content of the top 2 feet of soil was de- pleted to 25% of the available moisture. Moisture treatments C, F and G were initi- ated after the bloom stage. A. No water was applied after the bloom stage. C. Irrigation brought to field capacity the top 5 ft of soil when the average moisture content of the top 2 ft approached 25% of the available moisture 23 F. Irrigated according to treatment C. Application of white acrylic paint at weekly intervals beginning at or slightly prior to blooming 23 G. Irrigated according to treatment C. Light sprinkler irrigations were ap- plied every other day during high evaporative conditions during bloom- ing and fruiting period 23 to 1959 by sampling the soil to a depth of 5 feet and from 1960 to 1969 by the neutron scattering technique. The various plots were irrigated when the average soil moisture of the top 2 or 3 feet was reduced to the per- centages indicated in Tables 2, 3, 4, 5 and 6. Suffi- cient water was applied to each irrigation treatment to increase the soil moisture content to field capacity to a depth of 5 feet. Water was applied by level fur- row irrigation and was measured onto each plot with a 6-inch Sparling flow meter. Seven-inch portable aluminum gated pipe was used to convey water to in- dividual plots. Estimates of water use as influenced by treatments were made by the depletion technique. Blossom-End Rot Blossom-end rot of pear tomatoes as influenced by treatments was evaluated in 1962, 1963 and 1964 on Willacy loam soil. Relationships between BER and soil moisture stress and air temperatures were evaluated in 1962, 1963 and 1964. Incidence of BER was expressed on weight basis in 1963 and 1964. TABLE 7. SPACING, MOISTURE AND FERTILITY MANAGEMENT TREATMENTS AND THEIR INFLUENCE ON YIELDS AND BER OF Cl-‘Il GROWN ON HARLINGEN CLAY, FALL 1966 TABLE 8. INFLUENCE OF BROADCAST AND BANDED-l TREATMENTS APPLIED TO HARLINGEN CLAY SOIL, 196 BER Yield, 4/28/67 gal; Rggiff tons/acre BA Br lb/acre lb/acre BA’ Br’ "l. 0 0 2.7 2.7 51 51 17.5‘ 13.8‘ 3.9 3.1 49 46 35.0‘ 27.6‘ 4.6 3.0 s4 3s 52.4‘ 41.4‘ 4.2 3.4 59 19 87.4‘ 69.0‘ 4.9 3.0 59 32 174.8‘ 138.1‘ 3.9 3.0 61 40 ‘Each rate consisted of two treatments. In one trea p lizer (Ca H; P04 H2O) was broadcast and in another q fertilizer was placed. ‘BA = banded application. “Br = broadcast application. In 1965 and 1967 BER data on Har soil were obtained on several harvest ~ - June and July. In 1967 treatment E (Ta sisted of three sprinkler lines 100 feet U“ sprinkler positioned every l0 feet. Ligh applications were made twice a day for 20 a utes except on Saturday and Sunday wh" application was made. The applications, y modify stress in plant canopy, were com,‘ light rain. A 30-minute application n _ applying 12 to l5 gallons of water per ~~; tionships between BER and typical va Q. deficit in plant canopies under different on Harlingen clay were studied. Wet +5?‘ air temperatures and plant canopy tempe ' determined with Atkins thermistor the u - The influence of climatic conditi was studied under controlled conditions chamber. A modified Hoagland solution g 31 parts per million (ppm) P, ll7 ppm " Ca, 48.6 ppm Mg plus essential micronu’ N (l6) was used in growth chamber and I environments. Transpiration of fruits was evaluated ;_ trolled conditions using a wet thermistor - _ The surface area of fruits was determi" secting fruits into sections, tracing the I Treatment Row Yield, no. Irrigation management Fertility treatment spacing tons/acre i 1 Irrigated every furrow 25# P/A 38-inch 10.2 2 Irrigated every furrow Check 38-inch 7.6 3 Irrigated every other furrow 25# P/A 38-inch 11.0 4 Irrigated every other furrow Check 38-inch 9.1 5 Irrigated every furrow Check 76-inch 6.2 6 Irrigated every furrow 50# N/A 76-inch 6.6 7 Irrigated every furrow 50# P/A 76-inch 9.3 8 Irrigated every furrow 500# 76-inch 6.5 9 Irrigated every furrow 50# N/A-50# P/A 76-inch 8.3 1O Irrigated every furrow 50# N/A-50# P/A- 76-inch 8.0 10# Fe Chelate/A l}; , MOISTURE USE AND IRRIGATION DATA OF MOISTURE LEVEL TREATMENTS ON LAREDO CLAY LOAMS, 1958, AND WILLACY No. of irrigations‘ Soil Total Yield during Water moisture water (marketable) growing applied, Rainfall, depletion, used, ton / acre season inches inches inches’ inches 1 95 8’ 6.1 5 15.1 5.4 0.9 21.4 5.7 3 13.0 5.4 0.9 19.3 5.3 2 9.3 5.4 0.9 15.6 1 959‘ 5.1 4 11.7 5.7 4.8 22.2 6.1 2 8.9 5.7 5.2 19.8 7.4 1 6.0 5.7 4.8 16.5 . 24 (variety). i-W-2l 9 (variety). paper, and measuring the areas of the ith a planimeter. jdiffusion pressure deficits of fruits were ‘I by immersing the different size fruits in f- sucrose of different osmotic concentra- measuring the loss or gain in weight of (21). The diffusion pressure deficit of different size fruits was evaluated by the bility characteristics of different parts of p) ferent growth stages were evaluated with feter and expressed as a function of fruit i». and 1967, field and greenhouse experi- conducted to evaluate the influence of "Iwtments on BER. Tomato leaves were I'th a white reflective coating and kaolin ‘A -jective of reducing leaf transpiration. The coating was a petroleum resin emulsion ’ ies similiar to white acrylic paint. Cal- _~ 'de spray treatments (0.04 Molar) were ice during fruiting. toes were dry ashed according to the meth- ipman and Pratt (4) and cation concentra- I ined with an atomic absorption spectro- y; . The fruit parts were analyzed for Ca, I, Fe and Zn. I RESULTS AND DISCUSSION If Irrigation Treatments y turecl Soils of experiments conducted in 1958 and "I edo clay loam and Willacy loam, respec- 1 indicated in Table 9. In 1958, the wet 1 n moisture treatments caused a slight 4_ yield of marketable tomatoes (green wrap). e wet and medium moisture treatments fight decrease in yield of marketable toma- F Wrap)- ’ irrigated at planting time in 1958 but not in 1959. Plants were spaced 12 inches apart. i‘ moisture on February 19 minus soil moisture July 1; in 1959, soil moisture February 17 minus soil moisture June 15. Yields of green wrap tomatoes in 1960 were 10w, possibly due to climatic factors and a late crop. Rains prevented the proper evaluations of treatments. The tomato plots were irrigated at planting time in 1960 and 1962, but not in 1963. Irrigation treatments did not have a significant influence on yields in 1962 (Table 10) probably because of timely rains in March, April, May and June. In 1963, the wet and medium moisture treat- ments increased yields of Chico tomatoes (Table 10). The available soil moisture at planting time was low g in 1963. As indicated in Table 4, rainfall in 1963 was higher than rainfall in 1962, but was unevenly dis- tributed in 1963. The first significant rain (0.40 inch) did not occur until May 2. This was followed by 2.0 and 2.4 inches on May 5 and 6, respectively. These rains were probably responsible for yields of about ll tons on the nonirrigated plots. The yields of tomatoes on the dry and very dry treatments were not significantly different from the yields on the nonirrigated treatments. The reason for this response is not known, but it is possible that the potentials of the plants to produce higher yields were reduced when the plants were exposed to high soil moisture tension for an extended period of time. Many plants showed symptoms of severe moisture stress in 1963. The dry treatment was irrigated April 9; the very dry treatment was irrigated April 24. sThe yields of Chico tomatoes were increased by irrigation in 1964. Tomatoes grown at high moisture levels produced an average of 3 to 5 tons per acre more than toma- toes grown on dry treatments. In 1962, the yields of tomatoes planted on single rows on 38-inch beds were about 12 tons per acre higher than the yields of tomatoes planted on top of double rows on 76-inch beds. Tomatoes spaced 6 and 12 inches apart produced significantly higher yields than tomatoes 2 inches apart in 1963. How- ever, tomatoes spaced 12 inches apart did not pro- duce more than tomatoes spaced 6 inches apart. TABLE 10. YIELD, MOISTURE USE AND IRRIGATION DATA OF IRRIGATION AND SPACING TREATMENTS ON WILLACY LOAM, ,1 1963 AND 1964 k Soil Yield No. of Water moisture Irrigation (marketable) irri- applied, Rainfall, depletion, treatment ton / acre gations inches inches inches 19601 Wet 3.0 1 2.5 7.4 6.6‘ Medium 3.3 1 2.5 7.4 6.8 Dry 2.9 1 4.0 7.4 5.1 Very dry 3.7 0 none 7.4 7.9 Not irrigated 3.6 0 none 7.4 6.8 1962' 1 2 Spacing treatments’ Wet 32.0 21.7 5 16.9 3.4 4.9’ Medium 30.6 19.1 3 10.7 3.4 4.4 Dry 34.1 21.7 2 11.5 3.4 5.3 Very dry 31.9 20.7 1 7.0 3.4 5.1 Not irrigated 37.8 22.0 0 0 3.4 5.7 1963’ 1 2 3 Spacing treatments’ Wet 15.9 20.3 20.3 6 14.7 6.6 2.4‘ Medium 11.7 14.2 13.4 3 10.1 6.6 3.3 Dry 7.7 9.6 12.0 1 3.6 6.6 3.8 Very dry 8.1 9.5 8.8 1 5.4 6.6 4.8 Not irrigated 9.9 10.9 12.6 0 0 6.6 3.4 1964 1 2 3 Spacing treatments’ Wet 10.7 14.2 16.5 5 13.4 5.0 1.6 Medium 7.9 13.0 14.7 3 9.7 5.0 2.2 Dry 7.8 12.5 11.6 2 8.4 5.0 1.5 Very dry 4.2 8.9 9.8 1 5.6 5.0 2.3 Not irrigated 4 4 9.1 12.2 0 0 5.0 3.0 ‘Homestead No. 24 were irrigated when transplanted March 10, 1960, because January planted Rio Grande W-219 were It?’ Plants were spaced 12 inches apart. ‘Chico tomatoes were irrigated at planting time in 1962 but not in 1963. “See Table 3. ‘In 1960, soil moisture on March 16 minus soil moisture in June 22,- in 1962, soil moisture on March 6 minus soil moisture - 1963, soil moisture on March 4 minus soil moisture on June 25. Close-spacing of tomatoes in 1964 as in 1963 caused a marked reduction in yields. In 1964 tomatoes spaced 12 inches apart produced the highest yields. However, the difference in yields between tomatoes spaced 6 inches apart and those spaced 12 inches apart was not significant. Yield data in 1962, 1963 and 1964 indicate that close-spacing of tomatoes, even under a high level of moisture, reduced fruit size and caused substantial reductions in yields. This property is probably a function of plant type and /or varieties. Fine-Textured Soils The yields of spring-planted pear-type tomatoes from 1965 through 1969 on Harlingen clay as in- fluenced by moisture levels are shown in Table ll. The influences of moisture levels, amendment and fertility treatments on yields in 1965 are shown in Table 12. Moisture levels had a significant effect on yields—yields were low but ranged from 4 tons per acre on dry treatments to 6 to 6.5 tons per acre on wet treatments. Nitrogen and amendments did not significantly influence yields in 1965. Yields of Chico tomatoes in 1967 and 1968 were also low ranging in l0 \- yield from 1.2 on dry treatments t0 7 ‘f’ acre on wet treatments. In 1969 Chico high moisture levels produced l0 to 10 acre (Table 11). Chico tomatoes in the fall produced tons per acre on 38-inch beds and 6 to 76-inch beds in 196s (Table 7). . I c Hipp (15) reported that placement ofg pounds of P increased yields from 2.7 to acre in 1967. He also found that a b v- w; cation of about 175 pounds per acre of only 0.3 tons per acre more than toma, under control treatment (Table 8). 1 Water Requirement Medium-Textured Soils Moisture use in inches per day d May and at times in June ranged from a ti’ to almost 0.4 inch per day on Willacy n‘ ture use increased during April and May able soil moisture was high (Table 13).. evapotranspiration is higher during th‘ a ‘IELD, MOISTURE USE AND IRRIGATION DATA OF MOIS- iTRgEATMENT ON HARLINGEN CLAY Total p) No. of Soil water ' d, irri- Rainfall, moisture used, acre gations inches use inches 1965 (Chico Grande) 0 4.41 4.38 8.79 3 4.41 12.44 16.85 2 4.41 8.10 12.51 1 4.41 7.34 11.75 1967 (Chico) 1 4.73 6.48 1 1.61 3 4.73 10.41 15.14 2 4.73 8.69 13.42 3 4.73 11.81 16.54 1968 (Chico) 0 5.73 1.65 7.38 2 5.73 4.95 10.68 2 5.73 5.41 11.142 2 5.73 3.92 11.27’ 1969 (Chico Ill) 0 1.96 5.09 7.05 , 1 3 1.96 7.05 9.01 a 1.96 5.94 7.90’ m‘ 3 1.96 7.87 11.132 l; and 6. T» reflective treatments were part of experiment in. 1968 jThe primary obiectives of these treatments were to de- v er such treatments might conserve water. Detailed rted elsewhere (14). increased solar radiation, increased num- lpiring surfaces and blooming and fruit- } tomato plants. Maturation of fruits and 1 lack of available moisture caused de- soil moisture use in June 1962 and 1963. late in May caused moisture use to (y high in June 1964. requirements for tomatoes on medium- I, ls such as Willacy loam vary from year nding upon date of planting, time and (of irrigation and amount and time of sigh yields of Chico tomatoes were ob- i» as little as 9 inches of water in 1962 l‘ Irrigation treatments failed to increase l, ELD OF MARKETABLE CHICO GRANDE TOMATOES 1' BY MOISTURE LEVELS, NITROGEN FERTILIZATIONS T TREATMENTS, 1965 Moisture Ievel treatments‘ A B c D l Tons/ acre Average 5.2 7.2 6.3 5.0 5.9 4.4 6.2 6.5 4.4 5.4 3.9 6.1 5.4 4.7 5.0 j‘ 3.4 6.6 6.1 5.1 5.3 Iacre’ 3.8g 6.8 5.3 5.5 5.4 acre’ 3.6”‘. 6.3 5.6 4.5 5.0 - ‘ 4.1:‘ 6.5 5.9 4.9 t of moisture treatment sign at 5% Ievel. See ndment treatments not significant. Amendment ' a plied March 1963, (2000#/acre) and Novem- AI /acre). Amendment treatments were fertilized 0679. TABLE 13. AVERAGE SOIL MOISTURE USE IN INCHES PER DAY BY TOMATOES AS INFLUENCED BY IRRIGATION TREATMENTS AND TIME ON WILLACY LOAM, 1962, 1963 AND 1964 No. of irriga- tions f . lrrigofiontt biljogrL Use of water—-|nches/day treatment ing March April May June 1962 Wet 5 0.08 0.26 0.33 0.16 Medium 3 0.08 0.23 0.17 0.13 Dry 2 0.08 0.15 0.31 0.13 Very dry 1 0.07 0.10 0.17 0.12 Not irrigated 0 0.05 0.08 0.16 0.08 1963 Wet 6 0.03 0.37 0.36 0.14 Medium 3 0.03 0.28 0.25 0.13 Dry 1 0.03 0.17 0.20 0.10 Very dry 1 0.03 0.15 0.26 0.13 Not irrigated 0 0.03 0.0 0.12 0.13 1964 Wet 5 0.06 0.23 0.22 0.17 Medium 3 0.05 0.19 0.22 0.20 Dry 2 0.03 0.12 0.24 0.21 Very dry 1 0.05 0.09 0.23 0.22 Not irrigated 0 0.05 0.06 0.08 0.08 ‘See Table 3. yields in 4 of 6 years (Tables 9 and 10). A pre- planting irrigation and an irrigation at about bloom stage in dry years are needed to supply 10 to 12 inches of water required to produce satisfactory yields (10 to 20 tons per acre). The critical moisture demand period for tomatoes on these soils is the blooming and fruiting period. Pear tomatoes need to be irrigated 7 to 15 days after initiation of blooms to keep blossom-end rot at a low level of incidence (data presented on page PP). The primary root system and moisture depletion by tomatoes on medium-textured soil are in the top 2 to 3 feet (Table 14). Bloodworth, Burleson and Cowley (2) reported similar root concentrations for cotton, tomatoes and other crops on Willacy loam soil. Amemiya et al. (1) reported that cotton grown on medium-textured soils may extract water from below its primary root zone (0-3 feet). Moisture depletion at different soil depths as shown in Fig- ures 1 and 2 indicates that Chico tomatoes were able to extract moisture from 3 and 4 feet. TABLE 14. ROOT DISTRIBUTION OF TOMATOES AND COTTON AS INFLUENCED BY SOIL TYPE Soil depth, feet 0-1 1-2 2-3 3-4 4-5 Soil Crop Percent by weight Laredo clay loam Tomatoes 91.2 4.5 2.4 1.3 0.6 Willacy loam‘ Tomatoes 85.6 13.3 0.8 0.2 0.1 Willacy loam‘ Cotton 93.1 4.7 0.6 1.0 0.6 Willacy loam Cotton 62.1 22.8 7.9 4.9 2.3 Harlingen clay Cotton 99.0 0.7 0.2 0.1 0.0 Harlingen clay’ Tomatoes 96.3 3.7 0.0 0.0 0.0 ‘Data from Bloodworth, Burleson and Cowley (2). 'Root distribution determined using radioactive P. ll H . 0 R ¢ O ' - - ' u ‘ ‘l ‘ U. 54 ' ‘ \ _‘ ‘ Q a " u] \ ‘ s I 4 u o I I n .. ‘ Q - o c IIIIIIIIIIIII I‘ \ E '- g t.’ """" o0 \;§'\ i “Q I ' x .~'~ i? w 3 \ '''''' '~ 4 m \ ............................ ., 3' :2 \ A 5 TREATMENT ‘- -\ \ / \ ' 6 2- I FT. INCREMENTS "" Z __| Figure l. Moisture depletion f _- |- soil depths by Chico tomatoes " O Willacy loam on dry treatment]. u) Dates and amounts of precipitatif cated as ppt T; numbers 1' th - = to depth in feet. Time of first - ‘ dicated by T. ' i0 2'0 330 :0 203010 i0 3010 20 30 MARCH APRIL MAY JUNE T ll OJQTPPT. I FIRST 91.003337" , ‘ . PPT. Figure 2. Moisture deple- tion at different soil depths by Chico tomatoes grown on Willacy loam and irri- gated twice in i962. Dates and amounts of precipita- SOIL MOISTURE" INCHES/ FT. tion (Ppt T) and irrigations . F . (1,) are indicated; numbers | 6 50" 1' through 5' refer to depth 5 O ll ‘ in feet. Time of first bloom ' Q h is indicated by ‘ ‘ n0 2'0 30 f0 20 so 1'0 2'0 $0 n0 2“ MARCH APRIL MAY JU LCMOISTURE USE IN INCHES PER DAY AS INFLUENCED BY CHICO TOMATOES AND MOISTURE LEVEL TREATMENTS ON HARLINGEN a as shown. m. - Soils ijfrequirement of tomatoes was influenced " levels and stage of plant growth. Mois- l“ inches per day was 0.1 to almost 0.2 inch ay and from 0.2 to 0.3 in late May and 7 Water use from the beds by tomatoes - was about I5 percent more than from the t late in the season when water use from equal or greater than use from top of and Chico Grande tomatoes on fine- i s develop smaller plants than on medium- 3 . The primary root system of annuals 1 Table l4 is restricted to the top foot of p; re depletion on this soil (Figures 3 and Etlated in the top foot of soil. Significant m the 2nd foot did not occur until about y first bloom in the case of dry treatments jnd 60 days in the case of wet treatment 5‘ Gerard and Namken (13) found similar letion by cotton on these soil types- the i» water by cotton from below its primary -l'l foot) was insufficient to prevent reduc- and yield of cotton. n yields of spring-planted tomatoes and 1- (l3) can be produced on these fine- April 15 May 1 May 16 June 1 June 16 No. of to to to to to irrigation April 30 May 15 May 30 June 15 June 3O 1965 Inches/day’ 0 0.05 0.10 0.25 0.08 0.08 3 0.12 0.14 0.30 0.16 0.11 2 0.03 0.11 0.29 0.11 0.15 1 0.07 0.07 0.23 0.17 0.11 1968 Inches/day 0 0.03 0.10 0.12 0.12 0.09 2 0.06 0.13 0.17 0.22 0.19 1967 Inches/day’ April 1 April 16 May 1 May 16 June 1 to to to to to April 15 April 30 May 15 May 31 June 15 1 0.06 0.17 0.12 0.11 0.19 3 0.06 0.11 0.22 0.32 0.25 2 0.06 0.09 0.15 0.22 0.27 3 0.07 0.20 0.21 0.27 0.26 1969 Inches/day B’ F B 0 0.04 2 0.17 0.12 0.16 0.15 0.06 0.06 3 0.04 0 6 0.16 0.14 0.24 0.21 0.13 0.16 _and 6. n: in 1965 and 1968 were comparable; growing seasons in 1967 and 1969 were comparable—-thus, moisture use intervals textured soils with frequent light irrigation. Appli- cation of too much water is possible during this stage of plant growth because on these soils tomatoes are easily killed under conditions of poor aeration. Water requirement for spring tomatoes is 3 to 4 irrigations and a total of 12 to 15 inches. Unfortunately, the maximum yield of spring tomatoes (Chico III) was only about l0 tons. Low yields and high water re- quirement make tomato production on these soils uneconomical. Chico tomatoes planted in the fall produced about twice the yields (Table 7) and re- quired less water than those planted in the spring (Table ll). In addition, incidence of blossom-end rot in the fall is considerably less than in the spring. Blossom-End Rot Round-type tomatoes had no incidence of blos- som-end rot from I958 to 1960, and Chico had none in 1962 (Table 16). On medium-textured soils the relationship between BER and number of days of moisture stress in the primary root zone after initia- tion of blooming is parabolic as indicated in Figure 5. The intercept occurs at 7 days. This relationship would suggest that under the prevailing climatic con- ditions Chico tomatoes need to be irrigated 7 to 15 days after initiation of blooming to keep BER at a low level of incidence. Spurr (22) found that the 13 q‘ \ I 4.’ ‘r. k I / l \. 4 .-'/ / T o. 5"PP. TREATMENT IFT INCREMENTS f FIRST L48" ~- PPI 240 P%OOM PPT ‘f’ i? SOIL MOISTURE" INCHES/FT. k incipient stages of BER occur from 12 to l5 days conditions in 1962, 1963 and 1964 from after anthesis. Chico and Chico Grande tomatoes, 15, the production period for Chico to like the San Marzano tomato described by Spurr (22), medium-textured soils, showed that incidence; grew rapidly during the period of 9 to l5 days fol- with respect to the dry treatments was . .4 . . . . . . . . e . IO 2O 3O IO 2030 IO 2O 3O IO 2O 3O IO 2O MARCH APRIL MAY JUNE JULY Figure 3. Mois ~~ tion at different by Chico tome" with one irrigati lingen cIay in I9 and amounts of i” tion (ppt 1‘) and; (i) are indicated. ~ I’ through 5' ; in feet. Time of “i, is indicated by lowing anthesis. Spurr (22) and Wiersum (24) stated the number of hours above 90° F or high e that the disorder occurs during the relatively active conditions as indicated in Figure 6. phase of fmlt growdh Tomatoes on fine-textured soils made In 1962 Chico tomatoes grown under moderate growth and low yields and, compared with i, to high soil moisture stress on medium-textured soils on medium-textured soils, produced a small," had no BER, but tomatoes grown under moderate to (8, 9). These pear varieties on fine-textured high soil moisture stress in 1963 and 1964 had moder- duced most of their crop in May and June. I ate to high incidence. An evaluation of climatic of BER in the spring was high even under i‘ "J l n u I e I n I I I I n I \ a." n m Q85 Figure 4. Moisture deple- tion at different soiI depths by Chico tomatoes grown with three irrigations on Eiaylingend clay in #967. a es an amoun s o re- cipitation (ppt T) and ‘iarri- gation (l) are indicated. 2' | F1: | M E Amount of first irrigation S was not metered. Numbers I’ through 5' refer to depth in feet. Time of first bloom is indicated by 1‘. BLOOM I SOIL MOISTURE " INCHES/FT. 2.00" 2.00" l4 I I l‘* I V I I V I I V ' I ab 2o so IO 2o a0 no 2o so I0 2o so IO MARCH APRIL MAY JUNE J i964 4° 37.5 % + " 2 =-0.9l+0.0l83X R=O.823-— I963 IO °/o '0' g fi 19oz \ .+ + o 0 a/O \ L . 2o 3o 4o 5'0 so 2° 3° 4° 5° NUMBER OF nouns ABOVE 90°F DAYS Figure 6. Influence of climatic stress on BER of Chico tomatoes in Relationship between percent BER of Chico tomatoes and 1962, 1963 and 1964 on medium-textured soils. today; after initiation of blooming prior to irrigation or Fl" l9'°°*°' m" 0-5 W“) °" "‘°°"“""*°’““'°d ‘°"$- TABLE 1o. INCIDENCE or BLOSSOM-END ROT AS INFLUENCED BY l‘ YEARS AND TOMATO TYPES BLOSSOM END ROT-(°/o) 8 _ _ Incidence Flevels. IIICIdCIICC of BER 1n fall 1966 was of if“ ables 7 and _ blOSSOM- Texture ) Year Variety Type end rot of soil 1965 through 1967 on Harlingen Clay Soil 1958 Homestead No 24 Round None Medium 61166. Yfigardlf-‘SS 0f 1119mm‘? level tlfiat- 1959 Rio Grande w'-2i9 Round None Medium a’ lowest 1n early June and hlghest during 1960 Homestead No. 24 Round None Medium a 1m and early July» Incidence of BER 132i 5:22: 2:211:21 1232:: treatment vaned from a low of 32 percent to high a high of about 45 percent in 1966. 1°64 Chiw Smell pear High _ Nledium d . .d . fl d b . 1965 Chico Grande Large pear Very high Fine 4}" rot Incl ence as 1n uenqe _ lamolsuqle 1966-68 Chico Small pear Very high Fine jents for the 1967 crop 1s 1nd1cated 1n woo fall Chico Small pear Moderate Fine v 1969 Chico lll Small pear High Fine Figure 7. Blossom-end rot of tomatoes at w’ different times during the growing season i § ~___ _ _'d' on different moisture level treatments in _ -- v 1967. Treatments are described in Table 4. ‘f, I I I I Y g 2o 2s 3o 5 IO l J U N E _ J U LY 15 ,- a u LY I o ‘ o -- .' quur a PLUS. \ ~/ lr _ J- "nun" “‘\\ "u." l: D1,," "M-YIELD cunvz” l l n Q’ ' ; -,_ ‘t / lutv no ~ -,_ I’ "JULY a ..§"‘ ,4,» ' ‘fl §_ I.—_——|u¢ 4 - 40- \° L I P Q cc 30- D Z LIJ 20‘ E O U‘) 8 _J no Figure 8. Relationship between BER and lo- ID cation of sprinkler lines and BER and yields on moisture level treatment E, 1967. Arrows indicate positions of sprinkler lines. Treat- O L ment description in Table 4. o DISTANCE FROM BORDER-FEET In 1967 BER incidence on tomatoes which re- ceived sprinkler irrigation (treatment E) was less than 3 percent on June 15 and less than 5 percent on June 26 (Figure 7). The 3 to 5 percent BER probably occurred prior to initiation of sprinkling May 4, 1967, or during the period of May 30 to June 4 when high evaporative conditions prevailed at a time when the pump operating the sprinkler system was inoperative. Yield and blossom-end rot curves are almost mir- ror images of each other (Figure 8). Yield and in- cidence of BER on Chico tomatoes grown under treatment E varied with the location of the sampling site. Yields and BER incidence, (Figure 8) were functions of wind direction which modified the cov- erage of the plant canopy by the sprinklers. The prevailing wind was from the southeast blowing across the three rows of sprinklers at about a 45° angle. The plant canopy 9 feet from the border was not completely covered by the fine mist; the plant canopy 18 feet from the border received some water from two sprinkler lines, and the plant canopy 27.5 feet from the border received the best coverage be- cause it received some water from three lines. As the distance between plant canopy and sprinkler in- creased, coverage and influence of the sprinkler sys- tem decreased. The relationship between typical vapor pressure deficit in June in plant canopies at 2 to 3 PM and percent BER incidence June 26 as influenced by treatment is shown in Figure 9. Maintaining vapor pressure deficit (VPD) conditions below l3 to l4 mm of Hg prevented or kept BER at a very low level. This is difficult because in June when maxi- mum air temperatures are 90° to 97° F, the VPD of air in the plant canopy is sometimes more than the VPD of the surrounding air, especially when the l6 2o 3'0 4'0 50 tomato plants are under moderate to high stress. ' Climatic stress influenced the incidence“ on Chico tomatoes grown in a growth 1H ure 10). The tomatoes were first exposedi stress conditions. The growth of plant and at a peak when VPD conditions were 23.5 I», at 90° F and 35 percent relative humidity A 17.1 mm of Hg at 80° F and 35 percent RH 4 vigorous at VPD of 7.9 mm of Hg at 80° h, percent RH. This might have influenced? nitude of the differences. However, it ' i from the apparent linear or slightly curvi 4 tionship between BER and VPD that BER tion of climatic stress. Apparently VPD " above l4 to 15 mm of Hg will induce BER in Chico tomatoes. The maximum A ditions in controlled chambers described l0 were maintained for 8 to 10 hours. g 30. l- o a: g 2o- u E 3, no (f) 3 m O _ _ g i :55: 0 5 |o I5 20g MM OF HG VAPOR PRESSURE DEFI Figure 9. Relationship between BER on Ju-ne 26, 1967, vapor pressure deficit conditions at 2 to 3 PM in plo I June l6, 1967, under different moisture level trea I/////////////////////////, ’/////////////////////////////////////////// ‘ I flJ/ll/l/l/l/l/I/l/ll/l/ s |'o 2'0 2s MM OF HG VAPOR PRESSURE DEFICIT Autionship between BER and controlled climatic stress ¢ 4, f interval, it should be pointed out, is wger than the maximum VPD interval f _ in the field during the tomato produc- i tion from different size of Chico toma- ‘Y d using wet thermistors, showed a hyper- fii hip between transpiration per cm2 and TEMP ss°c a 25% an. van as an um or HG AIR FLOW a 1.2 L/H. A -O.74 Y= 3.33X = -O.92 ill I p‘ .. ‘ I‘ 7‘ n ‘ “ i 2' 1i é é WEIGHT 0F FRUIT-GMS. otionship between size of Chico tomatoes and tron- weight of fruit (Figure ll). Transpiration is high for Chico fruit of 2 to 3 grams (g) or less or of 2 to 3 centimeters (cm) or less in length. Typical BER first appears when the fruit is 2 to 3 g in weight and 2 to 3 cm in length. The transpiration per unit of surface for small fruits was as high or higher than the transpiration from the upper epidermis of cotton leaves as reported by van Bavel et al. (23); in a few instances transpira- tion of the very small fruit was about 50 percent of the transpiration rate of the lower epidermis. How- ever, the climatic stress induced by the conditions described in Figure ll was greater than that reported by van Bavel et al. (23). The gain or loss of water by different size Chico fruit in solutions of different osmotic concentrations is presented in Figure 12. Small fruit tend to lose water to sucrose solutions with osmotic pressures of 8 to 9 atmospheres. The medium size fruit gained weight until the osmotic pressures of solutions were 8 to 9 atmospheres. The larger fruit gained weight until the osmotic pressure of the sucrose solution was 15 to 20 atmospheres. Immersed stems of fruiting hands which had small and large fruits out of the solution showed the same trend. This would suggest that under high evaporative conditions small Chico fruit may lose or fail to gain water when soil mois- ture tensions of the effective root zone approach 10 atmospheres. The penetrability of the distal end of Chico tomatoes is a function of size (Figure 13). Data indi- cated that the middle of the fruit was much more permeable than the basal part and that the smaller . l-Illllll 6- E , -— l.O GM. -l5 -| O - 5 O +5 +|O H5 FOR TOMATOES < l.O GM. GAIN OR LOSS IN WEIGHT (7a) Figure l2. The gain or loss of water by different size Chico tomo- toes in sucrose solutions of different osmotic concentrations. 17 .90‘ ' .8 0~ 10¢ ' 2' "z, A _ 0.60 o '9'" . y "' x | o 9”" _ - z .60‘ ‘ofi,’ f _ 9 ‘"0 1"‘ u ""0 4 "u, m .501 I "o", T- ‘ "'00 u LIJ "I", z 0 11"", g LIJ p . "qn", 0 ‘ o Q- . a a , . lllllllllynn" .30.- .2o I I I i I ‘I? T’ 1.4 1.8 2.2 2.6 3.0 3:4 3.8 4.2 LENGTH - CM. Figure 13. The relationship between penetrability of blossom-end of Chico tomatoes and their length. the fruit the weaker or more permeable was the fruit wall. A rapid change in permeability occurred when the fruit was between 2 and 2.5 cm in length. Re- _ cently it was postulated that the lack of oriented cellulose molecules at the distal end of pear tomatoes was a possible index of lower cell wall strength (10, l1). These data indicate that the distal ends of pear tomatoes are more permeable to water movement and the cells at the end of fruit are more susceptible to breakdown. A resume of Ca and K contents of basal and distal parts of tomato fruit from different experi- TABLE 17. THE INFLUENCE OF DIFFERENT TREATMENTS AND GROWING CONDITIONS ON Ca, K, K=Ca RATIO AND BER OF CHI‘ gen clay had higher Ca contents and lo: ments and years is shown in Table 17. Ca not reduce BER incidence. Banded Ca ra A 8) tended to increase BER. These data a despite the high exchangeable Ca—-and inf. of Harlingen clay, the high CaCO3 cont l) — these tomatoes were not able to trans Ca to the fruit, particularly the distal porti fruit (Table l7). .' It is concluded that (a) the low Cai especially of the distal portion of the frui high percentage of K in the fruit, especi distal end and (c) the high K:Ca ratio in 4* part of the fruit probably are important '5 ing blossom-end rot. Data in Table 17 a ~- that Chico tomatoes produced in the fall N ratio than spring grown tomatoes. Simil _ tomatoes grown under lower evaporative (treatment E) had higher Ca content and Ca ratios than those grown under high c} conditions. " The white reflective coating, which r- the leaves from June 2 until time of sam _ 29, resulted in increased Ca content of n; and reduced KzCa ratio in the fruit. which at the time of application cov as; percentage of the upper leaf surface, did. age the leaves. This coating may have "g: transpiration and, therefore, increased m‘, Ca into the fruit parts. “ The K:Ca ratios of fruits as shown inc are considerably higher than values at»; Wiersum (24). These differences are parti =7 able in fruits of spring-planted tomatoes f Harlingen clay or in fruits produced in“, culture solutions under controlled conditi interesting to note that tomatoes having 1' l, tent and high K:Ca ratio can have very?» dence of BER (treatment E and tomatoes Catt Kt K=Ca Ratio Date of Basal Distal Basal Distal Basal Di t: sampling Treatment % % ‘jg June 29, 1966 Check 0.17 0.12 3.51 3.92 11 June 29, 1966 White reflective coating 0.22 0.15 3.39 3.76 8 "1 v June 29, 1966 CCICI: spray (0.04 M) 0.15 0.10 3.35 3.67 11 1 November 22, 1966 Fall-planted tomatoes 0.19 0.13 3.78 y 4.20 10 June 26, 1967 A‘ 0.12 0.03 2.85 3.55 12 ‘i June 26, 1967 c‘ 0.15 0.05 3.12 3.83 n t; June 26, 1967 D1 0.15 0.04 3.03 3.82 10 4. June 26, 1967 E‘ 0.18 0.05 2.93 3.69 8 Growth chamber I 80°F 35% RH 0.08 0.03 3.00 3.30 19 Growth chamber 80°F 45% RH 0.09 0.05 3.01 3.58 17 Growth chamber 80°F 70% RH 0.07 0.05 3.63 4.18 27 ‘Treatments are described in Table 4. 18 percent RH). These data indicate that conditions which reduce leaf transpira- Ca movement into the fruit. Treat- ' c conditions and fruit parts have ‘uences on Ca and K content of tomato 1;. transpiration from small Chico fruit Q-tn of water into fruit parts create a f4 by water loss from fruit can exceed _' Under high evaporative conditions, fslosses from the small fruit probably Q of the already sensitive, unstable tis- " in blossom-end rot. LITERATURE CITED . L., L. N. Namken and C. J. Gerard. 1963. fdepletion by irrigated cotton as influenced by I": and stage of plant development. Agron. J. i» M. E., C. A. Burleson and W. R. Cowley. 1958. i?!» tion of some irrigated crops using undis- Agron. J. 50:317-320. '~ L., A. E. Erickson, E. H. Kidder and R. Z. The interaction of climate and soil mois- i - use, growth and development of the tomato. ‘l p. Sta. Bul. 47. D., and P. F. Pratt. 1961. Methods of an- , plants and waters. Univ. of Calif., Div. of J., and R. V. Troxler. 1953. Relation of cal- pa. .- to the incidence of blossom-end rot in Amer. Soc. Hort. Sci. 61:346-352. ‘il C. M. 1957. Control of blossom-end rot of ~ . Amer. Soc. Hort. Sci. 69:309-317. C. M. 1957. Factors affecting calcium nutri- ‘_ , tomato and peppers. Proc. Soil Sci. Soc. of "1 425. . . 1966. Blossom-end rot of pear shaped toma- fj; rande Valley Hort. Soc. J. 20:134-141. 9]., and W. R. Cowley. 1964. The influence of p], -- spacing treatments on the production of _ Valley tomatoes. Rio Grande Valley Hort. f”. f]. and w. R. Cowley. 196s. A study of blos- of pear shaped tomatoes. Tex. Agr. Exp. Sta. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. ' 2s. 24. 26. Gerard, C. J., and B. W. Hipp. 1968. Blossom-end rot of ‘Chico’ and ‘Chico Grande’ tomatoes. Proc. Amer. Soc. Hort. Sci. 93:521-531. Gerard, C. J., C. A. Burleson, W. R. Cowley, L. N. Nam- ken and M. E. Bloodworth. 1964. Cotton irrigation in the Lower Rio Grande Valley. Texas Agri. Exp. Sta. Bul. 1014. Gerard, C. J. and L. N. Namken. 1966. Influence of soil texture and rainfall on the response of cotton to moisture regime. Agron. J. 58:39-42. Gerard, C. J. 1970. Influence of transpiration suppressants sprinkler irrigation and moisture levels on transpiration and evapotranspiration. Texas A8cM Water Resources Inst. Tech. Rept. No. 27. Hipp, B. W. 1970. Phosphorus fertilization of direct seeded tomatoes. Tex. Agri. Expt. Sta. B-1101. Hoagland, D. R., and D. E. Amon. 1938. 'The water- culture method for growing plants without soil. Univ. Calif. Agr. Exp. Sta. Cir. 347:1-39. Leeper, P. W. 1961. Chico. Tex. Agr. Exp. Sta. L-557. Leeper, P. W. 1966. Chico Grande. Tex. Agr. Exp. Sta. L-693. Leeper, P. w. 1969. TAMU Chico m. Tex. Agri. Exp. Sta. L-830. Maynard, D. N., W. S. Barham, and C. L. McCombs. 1957. The effect of calcium nutrition of tomatoes as re- lated to the incidence and severity of blossom-end rot. Proc. Amer. Soc. Hort. Sci. 69:318-322. Meyer, B. S., and D. B. Anderson. 1939. Plant Physiology. D. Van Nostrand Co., Inc., N.Y. Spurr, A. R. 1959. Anatomical aspects of blossom-end rot in the tomato with special reference to calcium nutrition. Hilgardia 28:269-295. van Bavel, C. H. M., F. S. Nakayama and W. L. Ehrler. 1965. Measuring transpiration resistance of leaves. Plant Physiol. 40:535-540. Wiersum, L. K. 1966. Calcium content of fruits and stor- age tissues in relation to the mode of water supply. Acta. Bot. Neerlandica 15. Wiersum, L. K. 1966. The calcium supply of fruits and storage tissues in relation to water transport. Acta Hort. 4:33-38. Wiersum, L. K. 1965. Invloed van groei en verdamping der vruchten op het optreden van neusrot bij tomaten. Overdruk uit Meded. Dir. Tuinb. 28:264-267. 19 The Texas Agricultural Experiment Station Texas AkM University College Station, Texas 77843 H. O. Kunkel, Acting Director-Publication rosmss mo r n’ U3. DEPARTM 1 AGRICUL