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Chris Ramcharan and Paul Hepperly

Twelve cvs. of Papaya were evaluated for yield and tolerance to drought, high soil pH and disease incidence under a non-pesticide low-input system. Superior yields were obtained from Barbados Solo (BDX 584-1) - 67.1 Kg/tree (tr) and 987 g/fruit (fr), Guanica (GU 2-1) - 60.7 Kg/tr and 888 g/fr, PR 6-65 × Cariflora (CF) - 46.6 Kg/tr and 700 g/fr, and CF - 48.5 Kg/tr and 607 g/fr. Most cvs. survived 19 months with peak yields at 15 months. Pencil top was major disease and only the Palau cv. exhibited St. Croix decline symptoms. Vigorous cvs. included GU 2-1, CF, PR 6-65 × CF and Criolla (CR) several plants of which are fruiting 26 months after planting. Chlorophyll data indicated that CF and CR cvs. had best tolerance to high pH conditions. Cvs. with large pulp size included GU 2-1 (3.7 cm) and SRS × CF (4.2). Brix analyses indicated sweetest fruits were from CF (14.2), SRS × CF (13.4), GU 2-1 (13.7) and PR 6-65 × CF (12.9).

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Gregory L. Reighard, William C. Newall Jr., and Charles J. Graham

Late spring freezes often result in significant flower bud kill in deciduous fruit trees. Some products have been marketed as frost protectant compounds which purportedly protect flower stigmas and ovaries from freezing injury and death. Two of these compounds, Frost Free and Frostgard, were tested at two locations in South Carolina over three years. Varieties `Junegold', `Loring', `Redhaven', and `Jefferson' were treated with Frost Free (FF) in years 1988-1990 and with Frostgard (FG) in 1990. Significant differences in fruit yield and vegetative growth occurred during this period, but no consistent trends were evident. In 1989, FF-treated `Redhaven' and `Jefferson' trees averaged 10.5 and 21.8 kg more fruit/tree than the controls. However, no lethal cold temperatures occurred during the bloom period. In 1990, FG-treated `Redhaven' trees averaged 8.0 kg more fruit/tree than the control trees. The fruit from FF-treated trees were lower in Brix, had less red color, and vegetative shoot growth was slightly greater than that of the FG and check trees. These data suggest that Frost Free may have plant growth regulator properties.

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Joseph A. Fiola and Donald W. Schaffner

The major limiting factors for commercial marketability of strawberries grown in the Northeast is firmness and shelf-life. The major objective of the research is to study basic and applied aspects of exogenous calcium treatments on yield and quality of New Jersey grown berries. In 1990, 8328-1 and 8237-1 (NJUS advanced selections), and `Earliglow' and `Raritan' standards, were treated with 4 foliar Ca sprays (Nutrical) at 10 day intervals from bloom through harvest. In 1991, sprays (3) were applied at bloom, bloom+15 days, and pre-harvest. An `Earliglow' plot was utilized to test timing: bloom, mid-spray, or pre-harvest. Leaf and fruit samples were taken from treated and untreated plots prior to each application. Instron texture tests were performed to quantify firmness; a taste panel evaluated quality (color, texture, flavor, and overall quality). With multiple sprays, there were no significant differences in yield, fruit size, and Brix%, between treatments; however there were significant differences between genotypes and a genotype-by-treatment interaction. The lone bloom spray treatment reduced fruit size. Ethylene was reduced with calcium treatment, respiration was unaffected. Differences in flavor attributes were genotype specific.

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J.P. Mitchell, D.M. May, and C. Shennan

Field studies were conducted in 1992 and 1993 to assess the effects of irrigation with saline drainage water on processing-tomato fruit yields and quality constituents. Saline water (ECiw = 7 dS/m) was used for 66% of the seasonal irrigation requirements in 1992 and 82% in 1993. Yields of tomatoes irrigated with saline water were maintained relative to nonsaline irrigation in 1992, but were decreased by 33% in 1993. Juice Brix and Bostwick consistency were generally improved by irrigation with saline water. pH was unaffected by irrigation treatment, and titratable acidity, an estimate of citric acid content, was increased only in 1993. Calculated quantities for various marketable processed product yields reflect the dominant influence of fresh fruit yield that masked, to a large extent, whatever quality enhancements that may have derived from saline irrigation. The substantial tomato yield reduction that occurred in the second year of this study in plots irrigated with saline drainage water, the gradual surface accumulation of boron, as well as the significant salt buildup in lower portions of the crop root zone following drainage water irrigations demonstrate definitive limitations to the reuse approach and restrict options for the crops that can be grown in this system and the frequency of saline drainage reuse.

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A.G. Reynolds, D.A. Wardle, C. Zurowski, and N.E. Looney

One of three levels (O, 1, 10 mg·liter-1) of the cytokinin-active substituted phenylurea compound CPPU was applied with or without 100 mg GA/liter to developing clusters of `Sovereign Coronation' and Summerland Selection 495 grapes (Vitis spp.). In a similar experiment, one of three levels (0, 1, 10 mg·liter-) of either CPPU or the related compound thidiazuron was applied to `Simone' and Summerland Selection 535. Both phenylurea chemicals tended to linearly increase cluster weight and berry weight while reducing degrees Brix, pH, and anthocyanins and increasing titratable acidity. A subsequent trial with O, 4, and 8 mg thidiazuron/liter on all four varieties yielded similar results. GA had no individual or synergistic effects. Due to the very low concentrations required, CPPU and thidiazuron show great promise as chemical tools for the increase of berry weight in seedless table grapes. Chemical names used: N-(2-chloro-4-pyridyl) -N'-phenylurea (CPPU); N1-phenyl-N'-l,2,3-thiadiazol-5-yl urea (thidiazuron);

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A.G. Reynolds, D.A. Wardle, A.C. Cottrell, and A.P. Gaunce

Paclobutrazol (PB) was sprayed on hedged `Riesling' (Vitis vinifera L.) vines at one of five concentrations (0, 1000, 2000, 3000, or 4000 mg·liter-1) as single annual applications over 3 years (1987-89). Observations were made on growth, yield, and fruit composition during the years of application and 1 year thereafter (1990) to test carryover effects. PB had no effect on vine vigor, expressed as weight of cane prunings, during the three application years, but reduced vine vigor linearly with concentration in 1990. Yield was reduced by PB in the first 2 years of the trial, while in one season cluster weight and berries per cluster were also reduced. °Brix was increased by PB during all 3 years of application; titratable acidity was reduced and pH increased in the first year of application. PB sprays significantly reduced lateral shoot length, mean leaf size on both main and lateral shoots, and total leaf area on main and lateral shoots. Winter injury to buds, cordons, and trunks was also reduced with increasing PB level. Residues of PB in fruit in the first year of application ranged from 9 μg·kg-1 at the 0-m·gliter-1 level to 638 μg·kg-1 at the 4000-mg·liter-1 level. PB shows promise as a viticultural tool for advancement of fruit maturity, with possible additional benefits such as improved vine winter hardiness. Chemical name used β -[(4-chlorophenyl) methyl]-α -dimethylethyl)-1-H-1,2,4-triazole-l-ethanol (paclobutrazol, PB).

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Martin L. Kaps, Marilyn B. Odneal, and James F. Moore

Wine and table grape vineyards were planted at Mountain Grove in 1985. Twenty-seven wine and 10 table grape cultivars were evaluated in respective 12 and 18 vine plots, replicated five times. Vineyard management practices were single curtain cordon training, dormant season balance pruning, protective spray program according to Missouri recommendations, grass sod row middles with preemergence herbicide applied underneath the trellis, and fertilization according to soil and petiole analysis. Cluster thinning and shoot positioning were done as needed. Productivity data was measured yearly and included: pruning weight, yield, cluster and berry weights, and juice °Brix, titratable acidity, and pH. Disease evaluation data was also taken on these cultivars. Based on these data and current market trends, two wine grape cultivar groups were identified: recommended, `Catawba', `Cayuga White', `Chambourcin', `Norton', `Seyval blanc', `Vidal blanc', and `Vignoles'; not recommended, `Aurore', `Baco noir', `Bellandais', `Chancellor', `Chelois', `Couderc noir', `DeChaunac', `Delaware', `Horizon', `LaCrosse', `Leon Millot', `Marechal Foch', `Melody', `Missouri Riesling', `Niagara', `Rayon d'Or', `Rougeon', `Ventura', `Villard noir', and `Vivant'. Three table grape cultivar groups were identified: recommended, `Mars' and `Reliance'; recommended for limited planting, `Canadice', `Vanessa', and `Vinered'; and not recommended, `Challenger', `Einset', `Festivee', `Himrod' and `Venus'. This information is used by growers to make cultivar decisions and also serves as a benchmark for comparing new grape germplasm coming into the state.

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Jude W. Grosser*, J.L. Chandler, and R.M. Goodrich

Sweet orange (Citrus sinensis L. Osbeck) is the most horticulturally important and widely grown Citrus species in Florida and worldwide, and `Valencia' is the most important cultivar for processing. Frozen concentrate orange juice has been the primary product of the Florida and Brazilian industries, but recently there has been a strong shift to not from concentrate (NFC) product in Florida. The higher quality NFC has a greater consumer appeal, and brings a higher market price. The development of higher quality oranges with expanded maturity dates will facilitate this change and should increase the competitive ability of the Florida industry. No true sweet orange cultivars have been developed by conventional breeding due to biological impediments, and alternative methods to obtain genetic variation are being investigated, including studies of somaclonal variation. We have produced nearly 1000 somaclones of `Valencia' sweet orange using organogenesis, somatic embryogenesis, and protoplasts. Following several years of fruit evaluation, early and late maturing high quality somaclones have been identified based on juice analytical data (brix, acid, ratio, juice percentage, juice color, and lbs. solids). These clones have also performed exceptionally in taste panel evaluations comparing them with the traditional mid- and late-season cultivars. Second generation trees of the most promising clones have been propagated for further evaluation, and superior processing clones will be released to the Florida industry in the near future. An overview of this program including pilot plant juice quality data and taste panel results will be presented.

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T.H. Morsil, A.D. Matthias, and J.L. Stroehlein

The effects of trellising on absorption of photosynthetically active radiation (PAR, 400- to 700-nm wavelength) by foliage and fruits, on fruit composition, and yield were studied in 1988 under semi-arid conditions using field-grown Vitis vinifera L. `Petite Sirah' grapevines in a mature vineyard. A vertical inclination was obtained by attaching shoots to a vertically arranged three-wire trellis; 60° shoot inclination from horizontal was obtained by attaching shoots to a “V-type” Tatura trellis; a standard two-wire trellis (control) was used in which shoots attached to the upper wire were permitted to orient downward to the vineyard floor. PAR absorption by foliage during mid-morning to mid-afternoon periods was highest in the standard trellis and lowest in the Tatura trellis. PAR available for absorption by fruits was lowest in the standard trellis and highest in the Tatura trellis. Analysis of fruit composition at harvest revealed that total dissolved solids (°Brix) was significantly higher for berries from the Tatura trellis than for the vertical trellis or the control. The Tatura trellis resulted in the highest alcohol content of wine. Per-vine yields did not differ significantly among the three trellis systems.

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W. Mark Kliewer and Jason Benz

The effects of 7 rootstocks (AxR#1, 110R. 5C, 3309, 420A, 1616 and 039-16) grafted to Cabernet Sauvignon (clone #8) in combination with 3 between row spacings (2, 3, and 4 m) and 2 in-row spacings (1 and 2 m) on the level of minerals in petioles sampled at full bloom and at veraison on the mineral composition of fruits at harvest were evaluated over a 3 year period (1991 to 1993) in a replicated field plot established at Oakville in 1987. 039-16 petioles had the highest level of K, Ca and NO3, whereas 420A had the lowest concentration of these minerals, the other 5 stocks being intermediate. Petiole Mg level was highest in 420A and lowest in 039-16. 039-16 fruits at harvest had the highest level of K, malate, and pH, whereas 420A fruits were lowest in these substances. Between row spacing showed no significant effects on the concentration of minerals in leaves and fruits. However, leaves from vines spaced 1 m apart within rows had lower levels of Ca and Mg than 2 m vine spacing. One m vine spaced fruits were lower in °Brix hut higher in titratable acidity and malate than 2 m vine spaced fruits. Regression analysis showed that the number of roots per unit volume of soil was positively related to the concentration of K in leaves and fruits, regardless of the rootstock used.