While ethephon [(2-chloroethyl) phosphonic acid] has increased yields of red fruits, its use as a pepper (Capsicum annuum L.) fruit ripening agent has been limited by premature fruit abscission and defoliation. We tested ethephon solutions of 0, 1500, 3000, 4500, and 6000 μl·liter-1 with or without 0.1M Ca(OH)2 as a one-time foliar application to field-grown paprika pepper in southwestern Oklahoma. There was a linear increase in fruit abscission with increasing ethephon rates in two out of three years, with or without added calcium. Ethephon at 6000 μl·liter-1 improved the percent of total fruit weight due lo marketable fruits in two out of three years, primarily by decreasing the weight of harvested green fruits. However, ethephon never significantly increased the dry weight of harvested marketable fruits over that obtained from the control. There also was no effect of ethephon on the intensity of red pigment extracted from dehydrated marketable fruits. The only significant effect of Ca(OH)2 was an undesirable increase in the retention of green fruits on the plants. Ethephon had little value as a fruit ripening agent for paprika under the conditions of our studies, and Ca(OH)2 was not useful as an additive to ethephon sprays.
James R. Cooksey, Brian A. Kahn, and James E. Motes
Douglas V. Shaw
The heritabilities of, and genetic correlations among, variables that describe internal and external color in fresh strawberry (Fragaria × anarrassa) fruit were estimated using factorial analyses of seedlings from 20 controlled crosses. Hunter L and a values, and a subjective score generated by comparison with color plates were obtained for seedling genotypes and their parents at two locations. Genetic effects were responsible for 33% to 61% of the phenotypic variance for color traits, after correction for location effects. Means for objective color variables differed significantly between locations, but means for subjective color scores did not. Genetic × location interaction variances were usually nonsignificant, and were < 12% of the phenotypic variance for all variables. Phenotypic and genetic correlations between objective and subjective color scores were significant and large (absolute values of r = 0.42-0.69; rg = 0.84-1.00). Multiple regression of subjective scores on L and a explained 69% and 59% of the phenotypic variation for external and internal color, respectively. Genetic correlations between measures of internal and external color were small and mostly nonsignificant, suggesting that separate sets of genes condition these traits.
Jan Bizjak, Nika Weber, Maja Mikulic-Petkovsek, Ana Slatnar, Franci Stampar, Zobayer Alam, Karl Stich, Heidi Halbwirth, and Robert Veberic
. The pigments provide essential cultivar differentiation for consumers and are implicated in the health attributes of apple fruit ( Espley et al., 2007 ). Fruit color and biosynthesis of anthocyanins can be regulated by light and ethylene ( Saure, 1990
Nana Millicent Duduzile Buthelezi, Tieho Paulus Mafeo, and Nhlanhla Mathaba
may affect fruit color development ( Santosh et al., 2017 ). Transparent bags let in more light than those that are a translucent blue or green. However, blue bags, especially in banana-producing regions, are mostly used for fruit because they transmit
Terence L. Robinson, Alan N. Lakso, and Stephen G. Carpenter
A field planting of `Empire' and `Redchief Delicious' apple trees (Malus domestics Borkh.) was established in 1978 to evaluate four planting systems: 1) slender spindle/M.9, 2) Y-trellis/M.26, 3) central leader/M.9/MM.111, and 4) central leader/M.7a. During the first 5 years, yields per hectare for `Empire' were positively correlated with tree density. In the second 5 years, the Y-trellis/M.26 trees produced the highest yields while yields of the other systems continued to be related to tree density. Cumulative yields were highest with the Y-trellis/M.26 trees. With `Delicious', the Y-trellis/M.26 yields were greatest during all 10 years despite lower tree density than the slender spindle/M.9. Yields of `Delicious' with the other three systems were a function of tree density during the 10 years. At maturity, canopy volume per tree was greatest on the central leader/M.7a trees and smallest on the slender spindle/M.9 trees; however, there were no significant differences in canopy volume per hectare between the systems despite large differences in yield. Trunk cross sectional area (TCA) per hectare was greatest with the Y-trellis/M.26 trees and smallest with the central leader/M.7 trees. Yield was highly correlated to TCA/ha. Yield efficiency with `Empire' was greatest for the slender spindle/M.9 system, followed by the Y-trellis/M.26, central leader/M.9/MM.111, respectively. With both cultivars, the central leader/M.7a system had the lowest yield efficiency. With `Delicious', there were no differences in yield efficiency for the other three systems. The greater yield of the Y-trellis/M.26 system was the result of greater TCA/ha and not greater efficiency. `Empire' fruit size was largest on the central leader/M.7a and the central leader/M.9/MM.111 trees and smallest on the slender spindle/M.9 and the Y-trellis/M.26 trees. With `Delicious', fruit size was larger with the Y-trellis/M.26 trees than the other systems. When fruit size was adjusted for crop density, there were no significant differences due to system with `Empire', but with `Delicious' the Y-trellis/M.26 trees had larger adjusted fruit size than the other systems. Crop density calculated using TCA correlated better to fruit size than did crop density calculated using annual increase in TCA, canopy volume, or land area. Fruit color and quality with `Redchief Delicious' were not influenced by system. With `Empire', average fruit color and soluble solids content were lower for the Y-trellis/M.26 and slender spindle/M.9 in some years when canopy density was allowed to become. excessive.
Previous research has shown that nitrogen fertilization rates may influence fruit quality characteristics of navel oranges [(Citrus sinensis) (L.) Osbeck]. The objective of this study was to determine, for equal seasonal N applications, if the timing of the last seasonal nitrogen fertigation promotes early fruit maturity or affects fruit size. The study consisted of four treatments with the total seasonal allocation of nitrogen fertilizer applied by ≈1 May, 1 June, 1 July, and 1 Aug. in an experimental site in a commercial orange grove in the southern San Joaquin Valley of California. The source of nitrogen was a liquid calcium ammonium nitrate injected through the irrigation system. No significant treatment differences in soluble solids concentration, titratable acidity, the ratio of soluble solids concentration to titratable acidity, percent juice, fruit color and fruit diameter were detected in fruit sampled in October. Similarly, in September, no significant differences in leaf nitrogen were found among treatments. These results do not support the hypothesis that applying the total seasonal application of nitrogen early in the season results in earlier orange maturity or larger fruit size, at least not for trees that have leaf N in the optimum range.
Chad E. Finn and James J. Luby
Progenies from a partial diallel mating scheme using 17 highbush (Vaccinium corymbosum L.), lowbush (V. angustifolium Ait.), and half-high (V. corymbosum/V. angustfolium hybrid) parents were subjectively evaluated for fruit color, picking scar, and firmness in two seasons. General combining ability (GCA) mean squares were significant (P ≤ 0.01 for all traits), but specific combining ability was significant for no traits (P > 0.05). However, the correlation coefficients between the GCA effects and the parental phenotype scores were low, indicating that selection of parents within this material based on their phenotype may not be indicative of progeny performance. GCA effects depended to some extent on the species ancestry. Vaccinium angustifolium parents produced progeny with relatively dark, soft fruit with large scars. Lowbush parents having light-blue fruit produced segregating progenies that were heavily skewed toward dark fruit, regardless of the color or species ancestry of the other parent. When the highbush and half-high parents were crossed with one another, segregation patterns were typical of predominately additive gene action.
C. Jasso-Chaverria, G.J. Hochmuth, R.C. Hochmuth, and S.A. Sargent
Two greenhouse cucumber (Cucumis sativus) cultivars with differing fruit types [European (`Bologna') and Beit-alpha (`Sarig')] were grown during two seasons in a perlite medium in black plastic nursery containers in a passively ventilated greenhouse in northern Florida to evaluate fruiting responses to nitrogen (N) fertilization over the range of 75 to 375 mg·L–1. Fruit production, consisting mostly of fancy fruits, increased quadratically with N concentration in the nutrient solution, leveling off above 225 mg·L–1 for both cucumber cultivars. Fruit length and diameter were not affected by N concentration in the nutrient solution. Leaf N concentration, averaged over three sampling dates, increased linearly with N concentration in the nutrient solution from 46 g·kg–1 with 75 mg·L–1 N to 50 g·kg–1 with 375 mg·L–1 N. Fruit firmness decreased with increasing N concentration and there was little difference in firmness between the two cultivars. Firmness was similar across three measurement dates during the spring harvest season, but increased during the season in the fall. Fruit color responses to N concentration were dependent on the specific combination of experiment, sampling date, and cultivar. For most combinations of experiment, sampling date, and cultivar, cucumber epidermal color was greener (higher hue angle) with increased N concentration. The color was darkest (lowest L* value) and most intense (highest chroma value) with intermediate to higher N concentrations.
Maria Claudia Dussi, David Sugar, Anita Nina Azarenko, and Timothy L. Righetti
Over-tree sprinkler irrigation cooling treatments were applied to `Sensation Red Bartlett' pear trees during the final 30 days of fruit maturity in 1992 and 1993 when orchard air temperatures were >29 °C. Fruit from cooled trees were more red and less yellow than fruit from noncooled trees, resulting in lower hue values by the middle of the harvestable maturity period in both years of study. In 1992, cooled fruit had a greater portion of the fruit surface covered with red blush than fruit that were not cooled. Fruit firmness decreased more rapidly in fruit from cooled trees than in fruit from noncooled trees, indicating advanced maturity. Accordingly, cooled fruit should be harvested earlier than noncooled fruit to maintain postharvest quality. Differences between cooled and noncooled fruit with respect to hue, surface blush, and rate of firmness loss were more pronounced in a warm season requiring frequent cooling than in a cooler season.
Chikako Honda, Hideo Bessho, Mari Murai, Hiroshi Iwanami, Shigeki Moriya, Kazuyuki Abe, Masato Wada, Yuki Moriya-Tanaka, Hiroko Hayama, and Miho Tatsuki
fruit color management such as through evaporation cooling ( Iglesias et al., 2002 , 2005 ). Therefore, optimal temperatures for fruit pigmentation have been reported for various apple cultivars using detached fruit ( Arakawa, 1991 ; Curry, 1997