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Benjamin G. Mullinix, Sharad C. Phatak, and Janet Cooper

Six tomato cultivars [Hotset, Petra, Stella, Big-O, Tropic, & Monte Carlo (fresh market)] were grown in a greenhouse in 1979 from July through November in 3 experiments. Exp. 1: The first two cultivars were used in a 15 cm, 30 cm, or 45 cm in-row spacing with rows spaced 60 cm apart. Cumulative fruit number and weight per unit area declined with increasing in-row spacing. Exp. 2: The first four cultivars were subjected to either cold or no cold treatment during germination before transplanting. No differences were found between the two treatments for mean fruit weight or total fruit number. Exp. 3: The last two cultivars were subjected to both the cold treatment and flower vibration. Cumulative fruit weight was greater for vibrated flowers. Greater mean fruit weight occurred earlier with cold treatment and declined significantly later in season, and was more pronounced in Tropic than Monte Carlo.

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Kathryn E. Brunson, Sharad C. Phatak, C. Robert Stark Jr., and Michael E. Wetzstein

Research results are presented of a multi-year study on eggplant in Southern Georgia comparing two sustainable production technologies to the conventional rye cover crop technology. The sustainable technologies utilize beneficial insect principles as a substitute for conventional pesticide controls. Preliminary results from the sustainable technologies using crimson clover and subterranean clover indicate that the higher yields under rye can be more than offset by cost reductions associated with selected sustainable technologies. Production budgets are developed for eggplant to indicate expected net returns under both the sustainable and conventional technologies

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Juan C. Díaz-Pérez, Sharad C. Phatak, David Giddings, Denne Bertrand, and Harry A. Mills

Tomatillo (Physalis ixocarpa Brot. ex Hornem) is a popular crop in Mexico and other Latin American countries. There is an increasing demand for this vegetable in the United States, particularly from the growing Latino population. However, there is limited information about tomatillo production. The objectives of this study were to determine the effects of plastic mulches on plant growth, yield, and root zone temperature in two cultivars of tomatillo. The study was conducted in Spring and Summer 2000. The design was a randomized complete block with a split plot arrangement, where plastic film mulch (black, gray, and silver mulches, and bare soil) was the main plot and cultivar (`Toma Verde' and `Verde Puebla]) the subplot. In the spring, mulch treatments had little effect on plant growth during the first 30 days after transplanting and there were no significant differences in fruit yields. In the summer planting, both early growth and fruit yields were greatest with the silver and gray mulch treatments and lowest on bare soil. Plant growth during the establishment was related with subsequent plant growth and yield. In mature plants, vegetative top fresh weight and total fruit yield were higher (P < 0.01) in the spring than in the summer. Total fruit yield (both seasons), marketable yield (spring) and cull yield (spring) were lower in `Toma Verde' than in `Verde Puebla'. Root zone temperatures (RZTs) in the spring (mean = 26.4 °C) were lower than in the summer (mean = 29.3 °C). In both seasons, mean RZT was highest under black mulch and lowest in bare soil. In the summer, plant growth and fruit yields tended to decrease with increasing RZTs. Tomatillo plants grown on mulches with a mean seasonal RZT of 30 °C had fruit yields that were 65% (`Toma Verde') or 50% (`Verde Puebla') lower respectively than those of plants on mulches with a RZT of 27 °C. There were no significant differences in foliar concentrations of N, Ca, Mg, S, B, Zn, Cu and Na among mulches. Foliar concentrations of the majority of mineral nutrients were not related with the mean RZT for the season.

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Kathryn E. Brunson, C. Robert Stark Jr., Sharad C. Phatak, and Michael E. Wetzstein

Research results are presented from a multi-year study on vegetable production in southern Georgia that compared two low-input production systems to the conventional rye cover crop technology. The low-input systems use beneficial insect principles as a substitute for conventional pesticide controls, but pesticides are used if needed. Preliminary results from the low-input systems using crimson and subterranean clovers indicate that crimson clover produces better yields and can “catch up” to the conventional rye system. The higher yields of the rye technology can be offset by the cost reductions associated with the low-input technologies. Production budgets were developed for 3 years of eggplant and 2 years of fresh-market tomato and bell pepper to reveal expected net returns under the low-input and conventional systems.

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Benjamin Jeyaretnam, Hazel Y. Wetzstein, Sharad C. Phatak, and Russel W. Carlson

Changes in lipid and total protein content of somatic embryos of pecan (Carya illinoinensis) were estimated during maturation, cold treatment alone (3, 5, or 8 weeks) or cold followed by dessication (3, 5, or 7 days). Triglyceride was estimated colorimetrically and methyl esters of fatty acids were analyzed by GC-MS. Total protein was extracted from the same tissue with 2% SDS in Tris·HCL buffer. Triglyceride content of enlarged somatic embryos was significantly lower than zygotic embryos and further declined after 5 weeks cold treatment. An even greater decline was observed during the desiccation treatment. The most abundant fatty acids in small and enlarged somatic embryos are linolenic > palmitic > oleic > stearic acid. However, the molar ratio of linolenic to oleic reached 1:1 after 5 weeks of cold treatment. During enlargement, protein content increased to levels found in zygotic embryos, with desiccation resulting in further elevation.

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Sharad C. Phatak, Jinsheng Liu, Casimir A. Jaworski, and A. Fazal Sultanbawa

The functional male sterile (fms) eggplant (Solanum melohgena L.) germplasm UGA 1-MS was crossed with two cultivars, `UGA 18 White' and `Florida Market' with normal anthers to derive F1, F2, and BC populations. Functional male sterility (fms) was governed by a single recessive allele. The gene symbol fms is proposed for this male sterile characteristic. The functional male sterility gene was linked to purple fruit color at the X/x locus. Our observations also revealed that the purple or violet color ware not only on the fruit peel, but also on the anthers and leaf buds if the eggplant fruit was purple or violet. In the transmission of parents and progenies of the cross of UGA 1-MS × `UGA 18 White', the purple line on the anther and leaf bud purple color ware tightly associated with fruit purple color. Thus, it is assumed that the allele X controls not only purple fruit, but also the expression of the purple line on the anther and purple leaf bud.

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Emillie M. Skinner, Juan Carlos Díaz-Pérez, Sharad C. Phatak, Harry H. Schomberg, and William Vencill

Sunnhemp (Crotalaria juncea L.) is a tropical legume that could be an important summer cover crop in the southeastern United States, but it has the potential for suppressing both crops and weeds. Allelopathic effects of sunnhemp on weeds, vegetable crops, and cover crops were evaluated in greenhouse and growth chamber experiments. In the greenhouse, ground dried sunnhemp residues (applied mixed with the soil at 1.6% w/w) reduced percent germination of lettuce (Lactuca sativa L.) and smooth pigweed (Amaranthus hybridus L.) to a similar degree as that caused by cereal rye (Secale cereale L. subsp. cereale) residues (applied at 1.5% w/w). The allelopathic activity of sunnhemp was greater in the leaves than in the roots or stems. In growth chamber studies, the mean reduction in germination (relative to the control) caused by sunnhemp leaf aqueous extracts was: bell pepper (100%), tomato (100%), onion (95%), turnip (69%), okra (49%), cowpea (39%), collard (34%), cereal rye (22%), sweet corn (14%), Austrian winter pea (10%), crimson clover (8%), cucumber (2%), and winter wheat (2%). In lettuce, carrot, smooth pigweed, and annual ryegrass, sunnhemp aqueous leaf extract reduced seedling length to a degree similar as that produced by rye aqueous leaf extract. Sicklepod [Senna obtusifolia (L.) H.S. Irwin & Barneby CA] germination was not inhibited by any of the sunnhemp or rye aqueous extracts. In conclusion, sunnhemp reduced the germination percentage and seedling growth of various crop species. The allelochemical activity in sunnhemp was primarily in the leaves and remained active at least 16 d after harvest under dry conditions. Sunnhemp's allelochemical effect may be a useful attribute for weed management in sustainable production systems. However, plant growth in the field in crops such as bell pepper, tomato, onion, and turnip may be impacted as a result of allelopathic activity of sunnhemp residues. Thus, weed management may be more effective when sunnhemp is grown in rotation with crops that tolerate the allelochemicals from sunnhemp, resulting in optimization of the rotation effects.

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Kathryn E. Brunson, Sharad C. Phatak, J. Danny Gay, and Donald R. Summer

Velvetbean (Mucuna deeringiana L.) was used in crop rotation to determine the influence on southern root-knot nematode (Meloidogyne incognita) in sustainable vegetable production. Replicated trials were conducted at four locations. Two cover crop treatments, crimson clover and subterranean clover, were used in the sustainable plots and rye was the plow-down cover crop for the conventional plots. Selected as the vegetable crops were tomato, pepper, and eggplant. Following the final harvest, velvetbean was planted into the sustainable plots and disked under after 90 days. Results from soil samples before and after velvetbean, indicated the sustainable plots had substantially reduced nematode densities, while most conventional plots showed increases. A correlation between location, treatment, root-gall indexes and nematode density occurred in all crops for 1992. In 1993 there was only a correlation between root-gall index and nematode density in pepper. However, root-gall indexes were significant for location and treatment in all crops.

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Kathryn E. Brunson, Sharad C. Phatak, J. Danny Gay, and Donald R. Sumner

Velvetbean (Mucuna deeringiana L.) has been used as part of the crop rotation in low-input vegetable production in southern Georgia to help suppress populations of root-knot nematode (Meloidogyne incognita) for the past 2 years. Over-wintering cover crops of crimson and subterranean clovers were used the low-input plots and rye was the plow-down cover crop in the conventional plots. Tomatoes, peppers, and eggplant were the vegetable crops grown in these production systems. Following the final harvest in 1992, use of nematicides in the low-input plots was discontinued and velvetbean was then planted into the low-input plots and disked in after 90 days. Results from the 1993–94 soil samples taken before and after velvetbean showed a continuing trend of reduced nematode numbers where velvetbean had been, while most conventional plots that had nematicides applied resulted in increases in nematode populations.

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Paul W. Leeper, Sharad C. Phatak, Durham K. Bell, Ben F. George, Edward L. Cox, George E. Oerther, and Brian T. Scully