Although the effects of salinity on yield of tomato (Lycopersicon esculentum Mill.) grown under arid and semiarid conditions are well known, little information is available on the effects of salinity on crops grown in more humid conditions. In Florida, availability of high-quality water for irrigation may be reduced because of increased domestic consumption and sea water intrusion. Two greenhouse studies were conducted to determine the influence of irrigation system and water quantity and quality on the growth of tomato and snap bean (Phaseolus vulgaris L.). Bean plant heights and weights were greater with drip irrigation than with subirrigation. Bean seed germination percentage, plant height, and shoot weight decreased linearly with an increase in electrical conductivity of irrigation water (ECi) from 1 to 4 dS·m-1. Tomato leaf water potential and plant height decreased linearly with increasing salinity. Tomato stem and leaf weights were greatest at the intermediate salinity (2 dS·m-1) during initial growth, and stem weights decreased linearly with increased salinity during flowering. With drip irrigation, concentration of N for both crops decreased and concentration of P increased with an increase in water application from 0.75 to 1.5 times the estimated evapotranspiration rate (ETa). Tomato and bean tissue Na concentrations increased linearly with increased salinity. Total fruit yield and average fruit weight decreased linearly in tomato, and marketable fruit yield decreased quadratically with increased salinity.
J.M.S. Scholberg and S.J. Locascio
S. J. Locascio and G. J. Hochmuth
Watermelons [Citrullus lanatus (Thunb.) Matsum. & Nakai] were grown with three rates each of lime, gypsum, and K during two seasons to evaluate their effects on fruit production and mineral concentration. The first experimental site was a recently cleared Sparr fine sand with an initial pH of 5.4 and Mehlich I extractable K of 32 ppm (low) and 948 ppm Ca. The second site was a virgin Pomona fine sand with a pH of 4.8, 28 ppm K, and 612 ppm Ca. `Crimson Sweet' fruit yield was reduced 10% with an increase in lime rate from to 4.48 Mt·ha-1 in the first season. In the second season, lime rate had no effect on yield. In both seasons, fruit yields were reduced 14% by an increase in Ca from gypsum from 0 to 1.12 Mt·ha-1. Fruit yields were not influenced by K rates from 90 to 224 kg·ha-1. Application of lime and gypsum increased leaf tissue Ca concentrations and decreased K. An increase in K application significantly increased leaf K and decreased Mg in the first season but not significantly in the second season. Fruit firmness and soluble solid content were not consistently affected by treatment.
S.J. Locascio and G.J. Hochmuth
Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] were grown with three rates each of lime, gypsum, and K during two seasons to evaluate their effects on fruit production and mineral concentration. The first experimental site was a recently cleared Sparr fine sand with an initial water pH of 5.0 and Mehlich I extractable K of 8 mg·kg-1 (very low) and 20 mg·kg-1 Ca (very low). The second site was a virgin Pomona fine sand with a water pH of 4.8, 28 mg·kg-1 K (low), and 612 mg·kg-1 Ca (high). `Crimson Sweet' fruit yields were reduced 10% with an increase in lime rate from 0 to 4.48 t·ha-1 in the first season. In the second season, lime rate had no effect on yield. In both seasons, fruit yields were reduced 14% with an increase in Ca from gypsum from 0 to 1.12 t·ha-1. On the soil testing very low in K, yield increased with an increase in K rate from 90 to 224 kg·ha-1 with no lime or gypsum. On the soil testing low in K, greatest yields were obtained with 90 kg·ha-1 K with no lime and gypsum. Application of lime and gypsum increased Ca and decreased K in seedlings but not consistently in older leaf and fruit tissues. An increase in K application increased leaf K in the first season but not in the second. Fruit firmness and soluble solids content were not consistently affected by treatment during the two seasons. Thus, on soils low in toxic elements (Mn and Al) such as used in this study, watermelon will grow well and tolerate a wide range of soil pH values without additional Ca from lime or gypsum.
S. M. Olson and Salvadore J. Locascio
Four experiments were conducted to evaluate the influence of transplant age and container size on `Green Duke' broccoli production. Transplant ages (weeks from seeding) were 3, 4, and 5 weeks in Exp. A, 4, 5, and 6 weeks in Exps. B and D and 3, 4, 5, and 6 weeks in Exp. C. Cell sizes were 2.0 cm (width) × 3.2 cm deep (2.0 cm), 2.5 cm × 7.2 cm deep (2.5 cm), and 3.8 cm × 6.4 cm deep (3.8 cm) with each transplant age. With the smallest container size (2.0 cm), yields were significantly lower in 3 of 4 experiments as compared to the 3.8 cm container size. In 2 of 4 experiments, yields were lower with the 2 cm size as compared to the 2.8 cm container size. In Exps. A and B transplant age did not influence yield, but use of the oldest transplants in Exp. C resulted in reduced yields while use of the oldest transplants in Exp. D resulted in the highest yields Generally, head weights followed similar patterns to the yields.
B. D. Rudert and S. J. Locascio
In the paper, Growth and Tissue Composition of Sweet Corn as Affected by Nitrogen Source, Nitrapyrin, and Season by B.D. Rudert and S J. Locascio (J. Amer. Soc. Hort. Sci. 104(4):520-523. 1979), there is an error in Table 2. The last 4 columns of data for Spring 1977 should be moved over 1 column to the right. The dry weights column for Spring 1977 should be blank.
B. D. Rudert and S. J. Locascio
Sweet corn (Zea mays L.) was grown to evaluate the effect of N source, N rate, time of N application, and the nitrification inhibitor, 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin), on crop efficiency and movement of applied N on a Kanapaha fine sand. Sweet corn yield was not affected by nitrapyrin rates of 0, 0.56, and 1.12 kg/ha, during 2 seasons. During a wet 1976 summer season, total yield was 65% higher with N applied as (NH4)2 SO4 than as Ca(NO3)2. Total yield increased linearly from 6. 1 to 9.8 MT/ha with an increase in N rate from 56 to 224 kg/ha as (NH4)SO4. With Ca(NO3)2, total yield averaged 4.9 MT/ha and was not influenced by N rate. During the drier 1977 spring season, marketable yield was not influenced by N source. Total yield increased linearly from 9.1 to 14.6 MT/ha with an increase in N rate. In the wetter season, the application of N in split rather than single applications as Ca(NO3)2 increased yield. During the dry season, timing of N application had no effect on yield with either N source. The suppressing action of NH4-N absorption on the absorption of other cations was evident but was not consistent throughout the study. The application of (NH4)2SO4 as compared to Ca(NO3)2 resulted in higher plant dry weights at an early sampling stage in the wet season but not during the dry season. Higher soil N (NH4-N + NO3-N) levels were maintained above a 20-cm soil depth with (NH4)2SO4 than with Ca(NO3)2 during the wet season.
P. A. Costigan and S. J. Locascio
Three glasshouse experiments were conducted in which “starter” N, P, and K fertilizers were incorporated either within or below gel used for fluid sowing pregerminated seed of ‘Avondefiance’ lettuce (Lactuca sativa L.) and ‘Derby Day’ cabbage (Brassica oleracea L. Capitata group). Addition of nutrients to the gel at salt concentrations between 384 and 1893 mg-ion/liter inhibited emergence of the pregerminated seeds. Additions to the gel at concentrations between 9 and 21 mg-ions/liter were too low to affect the growth of the plants. Nutrient solutions applied to the base of the furrow immediately prior to fluid drilling the seeds allowed higher concentrations of salts to be used without reducing emergence. Solutions that contained factorial combinations of 0.84 g/liter N, 1.86 g/liter P, and 2.34 g/liter K applied at the rate of 0.5 ml/cm of furrow increased lettuce dry matter production by up to 44% after 20 days growth, although there was no significant effect on the growth of cabbage. The increase in lettuce growth was mainly in response to P ‘starter’ fertilizer but the largest response was achieved with the N + P + K ‘starter’ treatment.
G.H. Clough, S.J. Locascio, and S.M. Olson
Squash (Cucurbita pepo L. var. melopepo) was grown at two locations with different soil types as a second crop in a succession cropping study that used previously cropped polyethylene-mulched beds. Squash was produced with drip or overhead irrigation and with concurrent N-K fertilization or residual fertilizer from the previous crop. Tissue mineral concentration responses to irrigation method were variable; in early fruit, N and K concentrations were higher with overhead than for drip, but leaf Ca and Mg concentrations were higher with drip than with overhead irrigation. Concentrations of N and K were higher with concurrent than with residual fertilization and increased with an increase in application rate. In contrast, concentrations of P, Ca, and Mg decreased with concurrent fertilization and an increase in application rate.
G.H. Clough, S.J. Locascio, and S.M. Olson
Broccoli (Brassica oleracea L. var. italica), followed by tomato (Lycopersicon esculentum Mill) or squash (Cucurbita pepo L. var. melopepo), and then broccoli were produced in succession re-using the same polyethylene-mulched beds at two locations with different soil types. First-crop broccoli yield was earlier and greater with drip than with overhead irrigation and increased as N-K rate increased from 135-202 to 270-404 kg·ha-1. On a tine sandy soil, yields of second and third crops produced with residual or concurrent fertilization increased with an increase in N-K rate. On a loamy fine sandy soil, yields also increased as the rate of residual N-K increased; yields of second and third crops did not respond to rate of concurrently applied N-K, but were higher with concurrent than with residual fertilization, except total tomato yields were similar with either application time. With drip irrigation and concurrent weekly fertigation, yields equalled or exceeded those obtained with preplant fertilization and overhead irrigation.
S. J. Locascio, S. M. Olson, and D. D. Gull
Tomatoes (Lycopersicon esculentum Mill.) were grown on a sand and loamy sand to evaluate the effects of K source, K rate, and Ca rate on plant nutrient uptake, fruit yield, and fruit quality. The K was applied at 200 and 400 kg K·ha-1 from KCl and K2SO4. Gypsum was applied at 0, 450 and 900 kg Ca·ha-1. On the sand, tomato N leaf tissue concentrations were higher with K2SO4 than KCl. Leaf K concentrations were higher and Ca contents were lower with the higher than lower K rate. At first fruit harvest, leaf Ca concentrations were linearly increased with an increase in Ca rate. Early and total fruit yields, however, were not influenced by K source, K rate, or Ca rate at both locations Marketable fruit were more firm with K2SO4 than KCl and with 200 than 400 kg K·ha-1 on the sand. Fruit were less firm on the sandy loam than sandy soil but was not affected by K source or rate on the former soil. Ca rate had no effect on fruit firmness on either soil. Fruit citric acid contents were higher with KCl than K2SO4 and with 400 than 200 kg K·ha-1, Fruit color and percentage dry weight were not affected by treatment.