Medium-sized triploid watermelons were evaluated in southeast Pennsylvania in 2002 and 2003 to determine the best adapted cultivars for this region. The 2002 season was unusually hot and dry, while 2003 was unusually cool and wet. Yields and fruit quality were compared for the eight cultivars that were grown both seasons to determine the effect of weather on seedless watermelon. Cooler temperatures reduced total fruit number and total yield but not average fruit weight or soluble solids. Researchers evaluating triploid watermelons over several seasons can compare size and °Brix among cultivars, but will need to be cautious when predicting total yields.
Timothy E. Elkner* and David H. Johnson
Angela R. Davis, Charles L. Webber III, Penelope Perkins-Veazie, Julie Collins, and Vincent M. Russo
Cultural practices have been reported to affect quality and phytonutrient content of watermelon. Knowing which varieties perform best under various production systems, and how these systems affect quality, yield, and phytonutrient content, is imperative to ensure high quality and yield. There is limited information on how watermelon [Citrullus lanatus var. lanatus (Thunb.) Matsum. & Nakai] varieties perform when grown with organic practices. Production characteristics of six watermelon varieties from certified organic seed sources were compared under high-(black plastic and mechanical cultivation for weed control) and low-input (no-till) organic culture. The high-input method utilized black plastic mulch and mechanical cultivation for weed control. The low-input utilized no-till planting. `Triple Star' was the most productive seedless variety in terms of number of fruit and marketable yield when data were combined across locations. `Early Moonbeam' produced the largest number of fruit, and the smallest fruit, of the seeded varieties. `Allsweet', a seeded variety, had the best marketable yield due to its larger size. `Triple Star' had the best quality (lycopene and °Brix content) when data were combined across locations. Among the seeded varieties, `Allsweet' had the best quality at both locations; however, average lycopene content on a per-fruit basis under low input production was not significantly different when compared to `Sugar Baby'. High-input production methods almost doubled the number of fruit produced for all varieties, producing greater yields, and heavier average fruit weights, but lower °Brix and lycopene content compared to the low-input production method.
Imed Dami, Cecil Stushnoff, and Richard Hamman
The response of grapevines to methanol was investigated at the Orchard Mesa Research Center in Grand Junction, CO. Optimum sublethal methanol dose levels, based on visual assessments, were 90% for leaves and 100% for trunks for 10 cultivars. Total soluble sugars (TSS) of the berries, monitored every week until harvest, showed significant differences with Muscat Blanc during veraison. Berries from the methanol-treated vines had higher TSS (16.4 °Brix) than controls (15 °Brix). However, no significant differences were observed later in the season when approaching fruit maturity. At harvest, data on yields as estimated by cluster weight, berry weight and berry size showed no differences between the two treatments. Methanol did not enhance cold hardiness of bud tissues. measured by differential thermal analysis. It was concluded that, although methanol has been reported to improve several physiological features of C3 crops, our study suggested that it has little or no practical effect on grapes. More data on the determination of sugars in berries by HPLC will be discussed.
Andrew G. Reynolds and Christiane de Savigny
Vestigial seeds of `Sovereign Coronation' table grapes frequently form partial seedcoats that are perceptible during consumption. This problem was addressed through cane/cordon girdling and gibberellic acid (GA3) sprays. `Sovereign Coronation' vines were subjected to one of five treatments [untreated control; cane/cordon girdled; 15 ppm GA3 at bloom (GA1); GA1 + 40 ppm GA3 14 days later (GA2); GA2 + 40 ppm GA3 14 days later]. GA3 had no effect on yield or clusters per vine, but postbloom GA3 treatments increased cluster and berry weights and reduced berries per cluster. Fruit maturity was not consistently affected by the treatments, although slight increases in °Brix and pH and decreases in titratable acidity (TA) were associated with postbloom GA3 treatments. Use of postbloom GA3 applications reduced the number and weight of vestigial seeds with developed seedcoats, and reduced the number and weight of undeveloped seeds as well in 2 of 3 years. Girdling increased cluster and berry weights, decreased °Brix and TA, and increased pH. Transpiration rate of leaves on girdled vines was also higher than control vines on one sampling date. Data suggest that use of bloom and postbloom GA3 applications to `Sovereign Coronation' may reduce the formation of perceptible vestigial seeds and thus improve the marketability of this cultivar.
T.M. Work, R.W. Work, A.A. Bushway, and J.R. Schupp
Increased consumer awareness of pesticide usage in fruit production and demand for reduced pesticide residue on produce are major incentives to investigate the integration of disease-resistant apple cultivars into commercial fruit production. Appearance, flavor, and texture are key attributes in determining consumer acceptance of these new cultivars. The objectives of this study were to examine the physical, chemical, and sensory characteristics of five DRCs, `Liberty', `McShay', `NY 75414-1', `NY 74828-12', and `NY 65707-19', at harvest and following commercial storage. Consumer panels were asked to indicate their opinion of appearance, flavor, and overall attributes using a 9-point hedonic scale. Firmness, sweetness, and tartness were measured using a 5-point “just right” scale. Sugars, Hunter color, pH, titratable acidity, texture, Brix, and browning were determined. Statistical analysis of the parametric and nonparametric data were performed using SAS. Significant differences (P < 0.05) were seen in titratable acidity, Brix, Hunter color, and texture. `Liberty' and `NY 65707-19' received significantly (P < 0.05) higher liking scores for overall appearance. Firmness, sweetness, and tartness liking scores decreased over storage. However, `Liberty' and `NY 75414-1' maintained acceptable scores for these attributes. `NY 74828-12' was found significantly lower in degree of browning. Based upon the performance of these cultivars, `NY 75414-1' and `Liberty' have the greatest potential for fresh-market consumer acceptability and `NY 74828-12” may serve as a good processing cultivar due to reduced browning.
Matthew W. Fidelibus, Frederick S. Davies, and Craig A. Campbell
Gibberellic acid (GA3) increases juice yield of processing oranges, but results are inconsistent. Preliminary research suggested that this variability might be related to application timing. Therefore, we conducted an experiment to determine the optimal time to apply GA3 for increasing juice yield of `Hamlin', `Pineapple', and `Valencia' sweet oranges [Citrus sinensis (L.) Osb.]. Mature trees of each cultivar were sprayed with ≈10 L of a solution of GA3 (45 g·ha-1 a.i.) and organo-silicone surfactant (Silwet, 0.05%) between 2 Sept. and 9 Dec. 1998, and 25 Sept. and 9 Dec. 1999, or remained non-sprayed (control). Generally, the earliest application dates were most effective at maintaining peel puncture resistance above that of control fruit, while the latest application dates resulted in the most green peel color at harvest. Juice yield of `Hamlin' and `Valencia', but not `Pineapple', was increased by GA3 at some application timings and harvest dates in both years. The increase in juice yield was related to time between application and harvest; juice yield of `Hamlin' was greatest ≈2 months, and `Valencia' ≈5 months after GA3 application. Treated fruit often had lower juice Brix than non-sprayed fruit, a phenomenon that often paralleled treatment effects on peel color. When treatments did not increase juice yield but reduced juice Brix, then yield of solids was sometimes lower than for non-treated fruit. Treatments generally delayed flowering of `Pineapple' and `Valencia' but not `Hamlin'.
Larry R. Parsons* and Ed Etxeberria
Earlier work has shown that moderate water deficits imposed on citrus trees can increase fruit Brix without adversely affecting yield. Increased water restrictions have been imposed on citrus growers as Florida's population continues to increase. The objectives of this study were to determine: 1) the effects of no irrigation in the fall and winter on orange fruit quality parameters in Florida; and 2) amount of potential irrigation water savings. Trees were irrigated identically in the spring and summer. A non-irrigation treatment was started on Hamlin and Valencia oranges in September and October, respectively, while controls continued to be irrigated following established irrigation practices. An additional non-irrigated treatment was started at the same time on the Valencias that consisted of a soil covering with a water barrier (Tyvek) to exclude rainfall. Stem water potential was monitored during the fall and winter to estimate differences in water stress among the treatments. Brix and organic acids increased in fruit from non-irrigated treatments when compared to fruit from irrigated trees. Results also demonstrate that reduced irrigation did not affect yield greatly. Amount of irrigation savings was determined for both cultivars that differ in maturity dates.
J. Siller, M. Muy, E. Araiza, M. Báez, R. Garcia, R. Báez, and J. Diaz
Carambola fruit collected at the dark-green, light-green, color-break, and ripe stages were evaluated during storage at 21C for up to 10 days. Fruit size, weight, postharvest changes in color, compositional characteristics, CO2 production, ethylene evolution, and weight loss were monitored daily. Fruit size ranged between 78 to 82 mm. Peel color luminosity and chroma values increased with maturity stage, while hue values decreased. However, hue and chroma values of the four ripening stages tended to decrease with storage time. Weight loss and fruit flesh firmness were both affected by storage time and ripening stage, and ranged among the maturity stages from 5.1% to 6.7% and from 2.11 to 0.94 kg-f, respectively. On dark-green fruit, total soluble solids and titratable acidity were 4.89° Brix and 0.808%, respectively. Fruit collected at the ripe stage presented values of 6.7° Brix and 0.412% titratable acidity. None of the fruit among maturity stages changed significantly during storage on these parameters. Carbon dioxide production increased from 6.06 to 21.83 ml CO2/kg-h during storage time among maturity stages and always was highest on ripe fruit. Fruit harvested at the color-break and ripe stages produced ethylene after 9 and 6 days, respectively, and ranged from 1.15 to 3.92 μl·kg–1·h–1.
Robert E. Rouse
Juice quality from 4-year-old `Valencia' sweetorange (C. sinensis (L.) Osbeck) nucellar seedling clones VS-F-55-28-X-E, VS-SPB-1-14-19-X-E, old-line clones V-10-12-7-X-E, V-51-3-3-(STG-64G-4)-X-E, and `Rohde Red Valencia' RRV-472-3-26-(STG-31-18)-X-E, RRV-472-11-43-(STG-19-2)-X-E were compared for percentage juice per fruit, “Brix, acid, °Brix/acid ratio, soluble solids per standard 40.9 kg field box, and juice color score. Rootstocks were sour orange, Smooth Flat Seville, Cleopatra mandarin, Sun Chu Sha, calamandarin, Valencia seedling, P. myoliare × Ridge Pineapple X73-26, Duncan grapefruit, Carrizo, Benton and C-35 citranges, Swingle and F-80-18 citrumelos, Rangpur lime × Troyer citrange, P. trifoliata, and Vangasay lemon. V-10-12-7 had the most juice. RRV-472-11-43 had less acid than the other clones. VS-SPB-1-4-19 had highest ratio and RRV-472-3-26 the lowest. Soluble solids per box were lowest for RRV-472-3-26. Juice color score was highest for the two `Rohde Red Valencia' clones and lowest for V-10-12-7. Rootstock affected all juice quality factors except juice color score.
Z.L. He, D.V. Calvert, A.K. Alva, and Y.C. Li
Fertilization is among the most important factors influencing fruit quality of citrus. Effects of Individual element such as N, P, or K on fruit quality have been well-documented. Much less has been done on the interactions of N, P, and K in relation to citrus fruit quality. A field experiment was conducted from 1994 to 1999 in a commercial grove on a Riviera fine sand (Loamy, siliceous, hyperthermic Arenic Glossaqualf) to investigate the effects of fertilizer rates and sources on fruit quality of 26-year-old `White Marsh' grapefruit trees (Citrus paradisi Macfad.) on Sour Orange rootstock (Citrus aurantium Lush). Fertilizer was applied as water-soluble dry granular broadcast (three applications/year) at N rates of 0, 56, 112, 168, 224, and 336 kg/ha per year using a N;P:K blend (1.0:0.17:1.0). There was a quadratic relationship between fruit weight or peel thickness and fertilizer rates. Fruit weight per piece increased with fertilizer rates from 0 to 168 kg N/ha per year, but decreased from 168 to 336 kg N/ha per year. Fruit size was small at zero or low fertilizer rates due to nutrient deficiencies. Large fruit sizes of `White Marsh' grapefruit in the sandy soil were achieved at fertilizer rate around 168 kg N/ha per year. Increasing fertilizer application rates higher than 168 kg/ha per year greatly increased the number of fruit per tree, but decreased the size of fruit. Peel thickness, which is related to the fruit size, declines at higher fertilizer rates. Increase in fertilizer rate from 0 to 336 kg N/ha per year increased solids content and fruit acid concentration of the grapefruit. Fertilization rate effect on fruit Brix concentration was more complicated. Brix concentration was not affected by increasing fertilizer rates from 0 to 168 kg N/ha-per year, but was increased at higher fertilization rates (168 to 336 kg N/ha per year). As a result, the Brix/acid ratio was, in general, decreased by increasing fertilizer rates.