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- Author or Editor: S. J. Locascio x
Green `Jupiter' bell peppers (Capsicum annuum L.) were grown in the spring and fall seasons of 1994 on polyethylene mulch with drip irrigation. Seedlings were planted on three dates in each season, either 2 weeks (spring) or 1 week (fall) apart, with N applied at rates of 0, 100, 200, or 400 kg·ha–1. Primary fruit were harvested upon reaching full size (diameter) and the bioyield-point (which reflects bruising susceptibility) measured at the fruit shoulder with an Instron machine; pericarp thickness was measured adjacent to the area where bioyield-point was measured. Dry weight of the fruit tissue was measured in the fall only. Bioyield force decreased with increasing N rate and increased with later planting time in the fall, but did not change with N rate and decreased only slightly with planting time in the spring. Pericarp thickness increased with N rate in both spring and fall, but increased with planting time in the spring while decreasing in the fall. Dry matter increased with planting time, but decreased with N rate in the fall peppers. These results indicate that bioyield force is not controlled by pericarp thickness, but rather may be more closely related to cell size or cell wall thickness, as suggested by dry weight differences.
Tomato (Lycopersicon esculentum Mill.) was grown on fine sand and fine sandy loam soils at two sites to evaluate effects of N and K fertilization practices on petiole fresh sap N and K concentrations and to determine N and K sufficiency ranges. Treatments included applying N (196 kg·ha–1) and K (112 kg·ha–1) either 0%, 40%, or 100% preplant. With 0% or 40% preplant treatments, the remaining N and K was injected through the drip irrigation system in six or 12 equal weekly amounts or by a variable injection rate with most of the N and K injected between weeks 5 and 10 of the season. Petiole sap K concentration declined during the season, but was not greatly affected by treatment. Petiole N decreased over the season from 1100 to 200 mg NO3-N/liter and decrease was greater for preplant N treatments. Petiole N was correlated with tomato yield, especially for petiole N measured in the period of 5 to 10 weeks after transplanting.
Tomato (Lycopersicon esculentum Mill.) was grown with drip irrigation on a fine sand and on a fine sandy loam to evaluate the effect of N and K time of application on yield. On the sandy soil, 196–112 kg of N–K/ha was applied with 0%, 40%, or 100% preplant with 100% or 60% applied in six or 12 equal or in 12-week variable applications. Marketable fruit yields were lowest with 100% preplant, intermediate with 100% drip-applied, and highest with 40% preplant with 60% drip-applied. With 100% drip-applied, yields were highest with 12 even than with six even weekly applications or with 12 variable N and K applications. With the 40% preplant, timing of application had little effect on yield. On the sandy loam soil in 1993, where only N was applied (196 kg·ha–1), yields were highest with 100% preplant, intermediate with 40% preplant and 60% drip-applied, and lowest with all N drip-applied. In 1994, when excessive rains occurred, yields were similar with all preplant and with split-N applications.
Maintenance of adequate available soil N for bell pepper (Capsicium annuum L.) growth is essential to high production in Florida and requires mulching, fertilizer placement, and timing of fertilizer application. Slow-release N was supplied as sulfur-coated urea, isobutylidene diurea (1BDU), or ureaformaldehyde and was compared at 3 N rates with soluble sources such as urea, ammonium nitrate, and ammonium sulfate on ‘Yolo Wonder’ pepper. In the first season, highest yields and N concentrations of tissue occurred where IBDU and urea were applied broadcast with mulch as compared with band placement. In the second season, broadcast fertilizer placement with mulch was compared with 3 split-fertilizer applications without mulch. Fruit yield was affected by a significant interaction among N sources, N rates, and mulch. Highest fruit yields were obtained with SCU and IBDU applied under mulch at 224 kg N/ha. Leaf N was higher during the season with slow-release N than with soluble N. Soil analyses data from samples taken throughout the season showed that N source and rate significantly influenced the soil available N measured as urea-N, NH4-N, and NO3-N.
Peppers (Capsicum annuum L.) were grown during 2 seasons on Blichton fine sand (Arenic Plinthic Paleaquult) to evaluate the effects of black polyethylene mulch and timing of N application on accumulation of applied N by the shoots and fruit. Nitrogen was applied at 224 kg/ha as 15-N depleted (NH4)2SO4 in a split application or in a single application with and without mulch. During a relatively dry season, total fruit yields and N accumulation were not influenced by treatment. At the end of the crop season, N accumulation from the 224 kg N/ha averaged 16.5% in the shoots, 2.2% in the immature fruit, and 15.8% removed in the harvested fruit for a total utilization of 34.5% (77 kg/ha). The soil supplied about 43 kg N/ha. During an extremely wet season, fruit yields and N uptake were influenced significantly by treatments. Fruit yields were 25.1, 5.5, and 17.5 T/ha with the mulch, no-mulch single, and the no mulch split application treatments, respectively. Total N utilizations by plant shoots, immature fruit, and harvested fruit were 41.8% (94 kg/ha), 7.6% (17 kg/ha), and 23.9% (54 kg/ha) of the applied N with the 3 treatments, respectively. Nitrogen quantities utilized from the soil with the 3 treatments were 27, 11, and 15 kg N/ha, respectively.
Modeling the growth of field-grown tomato (Lycopersicon esculentum Mill.) should assist researchers and commercial growers to outline optimal crop management strategies for specific locations and production systems. A generic crop-growth model (CROPGRO) was previously adapted to simulate the growth of fresh-market tomato under field conditions. Plant growth and development of field-grown tomato, and fruit yields, will be outlined and compared to model predictions for a number of locations in Florida, nitrogen fertilizer rates, and irrigation management practices. Possible application of the model to quantify effects of crop management on crop production will be discussed using simulated yield values for a wide range of environmental conditions.
Growth and production uniformity of potato (Solanum tuberosum L.) as influenced by conventional seepage irrigation and by subsurface drip irrigation was evaluated in field studies during two seasons in plots 16 rows (18.3 m) wide and 183 m long. Seepage irrigation water was supplied through ditches located on each side of each plot. Drip irrigation water was distributed through buried tubes placed under the beds 6.1 m apart extending the length of the rows. Water application throughout the plots was accomplished more rapidly with the subsurface drip system and water use during the two seasons was 33% less than with the conventional seepage system. Tuber yield during the first season was similar with the two irrigation systems. During the second season, plant growth, tuber development, and tuber yield were sampled on alternate rows beginning on each outside bed, at each end of each plot, and in the middle of the plots. Irrigation method and bed location among the 16 beds had little influence of potato growth and development. With water flow from north to south, plant growth, and tuber yield were significantly higher from potatoes growing at the north end, lowest in the plot center, and intermediate from potatoes growing at the south end. These data indicate that potato production with the two irrigation systems was similar.
Nitrate concentrations in the springs and rivers in northern Florida have been increasing, and several state agencies are interested in implementing nitrogen management programs on farms to reduce N entering the groundwater. Watermelon was grown in the first season of a six-season project under various cultural and fertilization programs to investigate the relationship of N management with N leaching. Treatments were a factorial arrangement of two cultural systems (polyethylene mulch with drip-irrigated beds and unmulched, overhead irrigated beds) and three N fertilization programs [N at the extension-recommended rate, N at the commercial-watermelon-producer rate (1.5 times recommended), or N at the recommended rate with 50% of N from poultry manure]. Nitrate in the soil beneath the watermelon crop was monitored at the 2-m depth with porous-crop suction lysimeters and soil sampling. Yields were greater with the mulch/drip irrigation system compared with the unmulched/sprinkler cultural system; however, fertilization program had no effect on yield. Nitrate-N concentrations in the soil solution at the 2-m depth with all fertilizer treatments were only slightly elevated (3 to 5 mg·L-1) above that in the unfertilized soil (< 1.0 mg·L-1) early in the season when no rain fell. Later in the season, soil solution nitrate-N concentrations at the 2-m depth increased to >50 mg·L -1 with the unmulched treatment and with the greater fertilization rate. Polyethylene mulch, drip irrigation, and recommended N rate combined to maintain groundwater nitrate-N concentration below 10 mg·L-1 for most of the production season and only slightly above 10 mg·L-1 during the summer off-season when rainfall was frequent.
A single lime application of 5.4 t/ha per 20 cm increment of soil to a depth of 60 cm controlled bacterial wilt (Psendomonas solanacearum E. Smith) up to 2 years in tomato (Lycopersicon esculentum Mill.) growing in a naturally infested soil. `Sunny' with 64% disease incidence, was the most susceptible, `Capitan' (20%) was intermediate, and `Caraibo' (5%) and `Hawaii 7997' (2%) were the least susceptible. Incorporation of lime 40 to 60 cm deep reduced bacterial wilt incidence in 'Capitan' by 75%, and 60% in `Sunny'. The number of bacteria in the soil was not affected by lime treatment. Soil pH and total Caincreased linearly with time and with depth of lime incorporation. Bacterial wilt control in `Sunny' and `Capitan' was associated with an increase in pH. Liming to 40 or 60 cm generally increased leaf Ca and decreased Mn, Zn, and Cu. `Hawaii 7997' contained significantly higher concentrations of Ca, Mg, and K, and lower Cu compared to 'Sunny'. `Hawaii 7997' produced significantly higher yields than the other cultivars. Deep lime incorporation increased fruit weight of `Sunny' by 184% and 'Capitan' by 79% as compared with 0 lime.
Two newly released cultivars of small watermelons [Citrullus lunatus (Thumb.) Matsum and Naki], `Mickylee' and `Minilee', plus two other cultivars, Baby Fun and Sugar Baby, were stored at various temperatures from 1 to 21C for up to 4 weeks plus 1 week at 21C over two seasons. All cultivars were susceptible to chilling injury (CI) when stored below 7C; however, `Minilee' was less susceptible than the other cultivars tested. Chilling injury increased with storage length. Conditioning at 26C for 3 days before storage at 1C reduced CI and increased the percentage of marketable watermelons after storage. Decay percentage increased with storage time and was highest on fruit held at 1C where CI led to decay. The flesh of `Mickylee' and `Minilee' was firmer than that of the other cultivars tested and `Mickylee' and Minilee' retained their firmness better during storage. Total soluble solids concentration decreased with increased storage temperature. `Minilee' watermelons were superior to the other three cultivars in postharvest storage potential and exhibited the least CI and decay.