physiological maturity ( Ferguson et al., 2005 ). Harvest is done by hand labor over a period of ≈2 months. Increased labor costs and low labor availability have intensified industry interest in mechanical harvesting. Unusually low temperatures during flower bud
Jacqueline K. Burns, Louise Ferguson, Kitren Glozer, William H. Krueger, and Richard C. Rosecrance
Jim E. Wyatt, James A. Mullins, and Charles A. Mullins
Several spacing, cultivar, ethephon and harvest sequence studies were made on summer squash in 1989 evaluating cultural practices which maximized marketable once-over yield of fruit for processing. Optimum spacing was 30 cm within rows and 45 cm between rows. The zucchini and yellow hybrids producing the highest marketable yield were `Classic' and 'Gold Slice', respectively. Ethephon applied at 0.77 kg/ha resulted in higher yield than no ethephon. Harvesting two times followed by a seven day delay before a once-over, destructive harvest produced a marketable yield equal to three harvests/week for three weeks. A prototype mechanical harvester has been used successfully on yellow hybrids; zucchini hybrids require more force for successful fruit separation.
Carl E. Motsenbocker, J. Blair Buckley, William A. Mulkey, and James E. Boudreaux
Field studies were conducted in 1991 with `Jalapeno-M' and `TAM' Jalapeno pepper. Plants were established by direct seeding at 10, 20, 30, and 40 cm in-row plant spacing. Lodged plants, fruit quality and yield were monitored. A commercial snap-bean harvester was evaluated for harvest. Closer plant spacings resulted in greater yields and reduced plant lodging. No interaction of variety with plant spacing was observed. There were, however, differences in several yield parameters due to variety. Fruit quality characteristics of mechanically and hand harvested pepper stored at 6 C were similar. The use of the mechanical snap-bean harvester appears to be a feasible technique to harvest Jalapeno pepper.
Matthew W. Fidelibus, Kimberley A. Cathline, and Jacqueline K. Burns
to mechanical harvest ( Studer and Olmo, 1971 , 1974 ). Berries on dried rachises tend to detach from clusters with their pedicels (cap-stems) attached ( Studer and Olmo, 1971 ), which helps to prevent rupturing and tearing of the berries ( Studer
Kevin L. Cook and Leonard M. Pike
An `intermediate leaf' hybrid pickling cucumber (TAMU 884304 X ARK H-19 `little leaf') was direct-seeded at four plant densities (94,570; 48,440; 32,290; 25,375 plants/ha) using four within-row spacings (15, 30, 45, 60cm) at two locations and two seasons. Optimum yield based on marketable fruit number, grade distribution and fruit quality occurred with 94,570 plants/ha. Optimum harvest time depended on location and season. Delayed harvest times were also evaluated. Harvests with fruit >5.1cm in diameter had severely reduced brining quality. Fruit did not enlarge or enlarged slowly to oversize. This resulted in a mixture of fruit ages within the largest marketable fruit grades. It is recommended that `little leaf' lines and their hybrids such as `intermediate leaf' be harvested when fruit 3.8 to 5.1cm in diameter appear and before oversize fruit are produced. Spacing did not significantly effect length/diameter ratio(LDR) but LDR was significantly greater for delayed harvests.
Reuben B. Beverly and Allen W. Byous
Bjorn H. Karlsson and Jiwan P. Palta*
Supplemental calcium application has been shown in our previous work to improve tuber quality and reduce internal defects. We evaluated the response under field conditions of five commerically significant cultivars to a combination of calcium nitrate, calcium chloride and urea (168 kg·ha-1 per season) over three seasons. We were able to determine that the cultivar with the greatest response to supplemental calcium for reduced bruising, `Atlantic' had the lowest levels of tuber tissue calcium. Conversely, cultivars with least response to supplemental calcium, `Dark Red Norland' and `Superior', had the highest levels of tuber tissue calcium. `Snowden' was both intermediate in response to calcium and tuber tissue concentration. Based on data for 3 years, we determined that across cultivars the calcium concentration at which tubers no longer respond is ≈250 ppm and ranges for individual years from 195 to 242 ppm. These results suggest that seasonal variation for individual cultivars may affect the tuber need for calcium for reduced bruising. Although the exact mechanism is not known, we believe that calcium supplemented to bulking tubers may lead to improved cell membrane stability, increased wall structure or enhanced ability of tubers to repair following injury. The results of our study show that supplemental calcium fertilization has the ability to significantly reduce the incidence of tuber bruising for several cultivars.
Brian A. Kahn, Yaying Wu, Niels O. Maness, John B. Solie, and Richard W. Whitney
Research was conducted to develop a cultural system that would permit a destructive mechanical okra [Abelmoschus esculentus (L.) Moench] harvest. Okra grown at a highly dense (HD) plant population of 25 × 23 cm and destructively harvested by machine was compared with control plants spaced at 90 × 23 cm and repeatedly and non-destructively harvested by hand. The control N fertilization regime was 45 kg·ha-1 of N preplant, followed by one or two topdressings, each with 22 kg·ha-1 of N. Treatments applied to HD plots were designed to be multiples of the control N fertilization levels. Preplant fertilizer was added such that the sum of residual soil N plus the added fertilizer would total to 45, 90, or 135 kg·ha-1 of N for the standard, intermediate, and highest rates, respectively. Topdressing rates were 22, 44, or 66 kg·ha-1 of N for standard, intermediate, and highest, respectively. Topdressing was timed to follow a mechanical harvest of the HD plots. Since there was only one mechanical harvest in the two 1995 studies, topdress N treatments did not affect yields from mechanical harvest in that year. Nitrogen treatments had few effects on fruit yield per hectare of HD okra, even when stem N concentrations equaled or exceeded those of control plants. The highest N rate tended to delay fruit production. Increasing N rates did not affect the marketable fruit yield obtained by mechanical harvest of HD plants expressed as a percentage of the total cumulative marketable fruit yield from control plants. Physiological factors appear to be limiting the potential for densely planted okra in a destructive mechanical harvest system rather than horticultural factors such as N nutrition.
Two field experiments were conducted in Bet Hashita (1992) and Newe Ya'ar (1993), Israel, in order to examine the possibility of using plant growth habit, chlorflurenol, and plant population density to concentrate yield of pickling cucumber (Cucumis sativus L.) under a simulated once-over mechanical harvest system. Two near-isogenic cucumber lines, WI 1983G normal and WI 1983G little leaf, were grown under three plant densities, 5, 10, and 20 plants/m2, and at flowering half of the plants were treated with 50 mg·L-1 chlorflurenol solution. The little leaf line produced a smaller canopy than the normal line under five plants/m2 but a larger canopy under 20 plants/m2. The average commercial yield of the little leaf line was higher than that of the normal leaf line by 28% and 55% in Bet Hashita and in Newe Ya'ar, respectively. The highest yield of each line was achieved under the highest plant density. The average commercial yields under 20 plants/m2 were 1.13 and 0.91 kg·m-2 in Bet Hashita and 1.86 and 0.92 kg·m-2 in Newe Ya'ar for little leaf and normal leaf, respectively. Chlorflurenol increased fruit number per unit area but did not increase yield. Nevertheless, it increased the proportion of small fruits, which are more valuable. The present study shows that the little leaf growth habit can increase the yield concentration in pickling cucumber and make this crop more suitable for a once-over mechanical harvest. Chemical name used: methyl-2-chloro-9-hydroxyfluorene-9-carboxylate (chlorflurenol).
James R. Cooksey, Brian A. Kahn, and James E. Motes
Nontreated seed, primed seed, and transplants were compared for effects on stand establishment, plant morphology, and yield of paprika pepper (Capsicum annuum L.). Nontreated seed was satisfactory for stand establishment, although primed seed had the potential to provide greater initial stands. When populations were made equal by thinning, there were few differences in stem and leaf dry weight, fruit yield, or plant morphology attributed to seed treatment. Generally, morphology of plants established by direct seeding was favorable for mechanical harvest. Using transplants did not result in higher marketable fruit yields than direct seeding in 2 of 3 years. When compared to plants established by direct seeding, three trends were consistent across all 3 years for plants established by transplanting: 1) they were more massive, 2) they had larger vertical fruiting planes, and 3) they had more branches. These traits increase the difficulty of mechanical harvest and create the potential for more leaves and stems (trash) in the harvested product. Thus, transplanting is not recommended for stand establishment of paprika pepper intended for mechanical harvest.