). Fruit density affected return bloom similarly in both years. When 2010 and 2011 return bloom data were pooled, significantly more floral buds per fruiting spur were observed for T1 and T2 relative to controls (21% and 33%, respectively), though
Todd C. Einhorn, Debra Laraway, and Janet Turner
D. Scott NeSmith and Gerard Krewer
Plants of the rabbiteye blueberry (Vaccinium ashei Reade) cultivars Brightwell, Climax, and Tifblue were subjected to pollination with bees or to applications of 250 mg·L-1 of gibberellic acid (GA3) to examine the influence on fruit size and maturation period. Plants were thinned to a similar fruit density (FD) 4 weeks after anthesis. `Tifblue' and `Climax' fruit were smaller on GA3-treated than on bee-pollinated plants, but no difference was observed for `Brightwell'. The fruit maturation period for `Climax' was not affected by treatments, but `Brightwell' and `Tifblue' fruit on pollinated plants ripened 2 weeks earlier than fruit on GA3-treated plants. These data suggest that excess fruit load is not the primary factor responsible for the smaller fruit size and lengthened fruit development period resulting from GA3 applications to rabbiteye blueberries.
Tory Schmidt, Don C. Elfving, James R. McFerson, and Matthew D. Whiting
2004 but were excluded from the trial. Regression analyses revealed that crop load was associated with powerful linear and quadratic reductions of bloom density, fruit density, and yield in the year after treatment ( Table 1 ). The application of GA 4
Valdomiro A.B. de Souza, David H. Byrne, and Jeremy F. Taylor
Seedlings of 108 families from crosses among 42 peach [Prunus persica (L.) Batsch] cultivars and selections were evaluated for six plant characteristics in 1993, 1994, and 1995. The data were analyzed by using a mixed linear model, with years treated as fixed and additive genotypes as random factors. Best linear unbiased prediction (BLUP) was used to estimate fixed effects. Restricted maximum likelihood (REML) was used to estimate variance components, and a multiple trait model was used to estimate genetic and phenotypic covariances among traits. The narrow-sense heritability estimates were 0.41, 0.29, 0.48, 0.47, 0.43, and 0.23 for flower density, flowers per node, node density, fruit density, fruit set, and blind node propensity, respectively. Most genetic correlations among pairs of traits were ≥0.30 and were, in general, much higher than the corresponding phenotypic correlations. Flower density and flowers per node (ra = 0.95), fruit density and fruit set (ra = 0.84) and flower density and fruit density (ra = 0.71) were the combinations of traits that had the highest genetic correlation estimates. Direct selection practiced solely for flower density (either direction) is expected to have a greater effect on fruit density than direct selection for fruit density.
Yiannis G. Ampatzidis and Matthew D. Whiting
same crew, within 1 d and in the same orchard, is likely the result of variability in fruit density within trees (i.e., light crop density may reduce efficiency), tree size as well as fruit accessibility (i.e., workers might pick fruit from ground or on
David Sugar, Timothy L. Righetti, Enrique E. Sanchez, and Habib Khemira
Management of pear (Pyrus communis L.) trees for low N and high Ca content in the fruit reduced the severity of postharvest fungal decay. Application of N fertilizer 3 weeks before harvest supplied N for tree reserves and for flowers the following spring without increasing fruit N. Calcium chloride sprays during the growing season increased fruit Ca content. Nitrogen and Ca management appear to be additive factors in decay reduction. Fruit density and position in the tree canopy influenced their response to N fertilization. Nitrogen: Ca ratios were lower in fruit from the east quadrant and bottom third of trees and from the distal portion of branches. High fruit density was associated with low N: Ca ratios. Nutritional manipulations appear to be compatible with other methods of postharvest decay control.
Jeffrey K. Brecht, Robert L. Shewfelt, Joseph C. Garner, and E.W. Tollner
Cross-sectional X-ray-computed tomography (X-ray CT) images through the equator of tomato fruit (Lycopersicon esculentum Mill., cv. Sunny) ranging in maturity from immature (Ml) to advanced mature green (M4) revealed localized differences in X-ray absorption related to the formation of locular gel during maturation of the fruit. While maturity stage was poorly correlated with average X-ray absorbance and standard deviation or with average fruit density and water content, significant relationships' existed between maturity stage “and the number of image pixels with absorbance values >10 (Ml vs. M2 vs. M3) or 20 (M3 vs. M4) Hounsfield units. Using discriminant analysis, a relationship was developed that correctly identified the maturity class of 77% of the fruit and placed 96% of the tomatoes into the correct or an adjacent class.
T. Caruso, P. Inglese, C. Di Vaio, and L.S. Pace
Fruit thinning is the most effective tool in regulating fruit growth potential for early-ripening peach and nectarine (Prunus persica) cultivars, and the common strategy is to space fruit 25 to 30 cm (9.8 to 11.8 inches) throughout the canopy, while scarce attention to the canopy environment in which the fruit develops. It is likely that different light environments within the canopy require different thinning patterns and to test this hypothesis, an experiment was set up to evaluate various fruit thinning patterns (fruit densities) in relation to fruit location within the canopy of early-ripening `May Glo' nectarine trees trained to Y-shape. Differentiated fruit thinning resulted in higher yield efficiency due to a higher fruit number and average fruit weight. Differentiated thinning hastened fruit harvest and shortened the harvest period. Differentiated thinning reduced fruit variability within the tree in terms of size and soluble solids content, resulting in a higher crop value.
Uri Lavi, Emanuel Lahav, Chemda Degani, Shmuel Gazit, and Jossi Hillel
Genetic variance components for avocado (Persea americana Mill.) traits were estimated to improve avocado breeding efficiency. The additive and nonadditive genetic variance components were calculated from the variances between and within crosses. In all nine traits examined, i.e.-anise scent, fruit density, flowering intensity, fruit weight, harvest duration, inflorescence length, seed size, softening time, and tree size-a significant nonadditive genetic variance was detected. Additive genetic variance in all traits was lower and nonsignificant. The existence of major nonadditive variance was indicated also by narrow-sense and broad-sense heritability values estimated for each trait. Therefore, parental selection should not be based solely on cultivar performance. Crosses between parents of medium and perhaps even low performance should also be included in the breeding program.
Stephen M. Southwick, Kitren G. Weis, James T. Yeager, and Hong Zhou
Whole-tree sprays of Release LC [predominantly gibberellic acid] (GA,) were applied in a commercial peach [Prunus perisca (L.) Batsch.] orchard in the California Central Valley on three dates from mid-June (about 90 days after full bloom = 28 days before harvest) to late July (14 days postharvest) 1993 at 50, 75, 100, and 120 mg·liter-1. Gibberellin (GA) reduced the number of flowers differentiated in 1993, thereby reducing fruit density in 1994, when sprays were applied by early July 1993. Sprays in late July did not reduce flowering and fruiting density in the following year. In 1994, there were fewer fruit located on the proximal third of the shoot after GA sprays of 75,100, and 120 mg-liter' applied on 15 June compared to hand-thinned controls, and reduction was linear with increase in GA rate. Fruit numbers in the middle and distal sections of shoots were reduced by all 15 June and some 9 July GA sprays, with fewer fruit as concentration increased. However, the distribution of fruit within shoot sections, after GA treatments during floral differentiation, expressed as a percentage of the total number of fruit along fruiting shoots, showed even fruiting compared with hand thinning. Due to reduced flowering in response to GA treatments in June and early July 1993, the hand-thinning requirement was significantly reduced, with no thinning required in 1994 from 15 June 1993 GA sprays. All sprays applied in early July resulted in 40% to 60% fewer fruit removed during thinning than the nontreated controls. Sprays in late July were ineffective. Sprays of GA applied in mid-June at 50,75, 100, and 120 mg·liter and sprays of 120 mg·liter-1 GA applied in early July (4 days preharvest) increased the firmness of `Loadel' cling peach (about 26% improvement in June sprays) in 1993. The salable yield of fruit (after removal of the undersized fruit) was the same on hand thinned and on non-hand thinned trees treated with GA on 15 June at 50 mg·liter-1. The salable yield of fruit was increased by GA sprays of 50 and 75 mg·liter applied on 9 July 1993 compared to controls. There were no differences in fruit size (by weight or diameter) among the aforementioned treatments and hand thinning. GA sprays of 75,100, and 120 mg-liter' applied on 15 June 1993 tended to reduce salable yield, but fruit size increased with decreased yield. Based on the results obtained in 1993 and 1994, we believe that Release LC has good potential for chemically thinning peaches in California.