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1 Present Address: Tree Fruit Research and Extension Center, Wash. State Univ., 1100 N. Western Avenue, Wenatchee, WA 98801. This research was supported by operating grant no. A6697 of the Natural Sciences and Engineering Research Council (NSERC) of

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Six irrigation strategies were imposed on a block of O'Henry peach trees irrigated by fanjets. Treatments received different percentages of ET during the various stages of fruit growth and postharvest. ET was estimated by a large weighing lysimeter containing 2 trees and located in the center of the block. Fruit diameters were measured weekly and final fruit weights were determined at harvest. Adjusted fruit weights were estimated by statistically adjusting each treatment to the same fruit load.

Adjusted fruit weight correlated well with soil water content during the month before harvest but not during early stages of fruit growth. Treatments which applied 50% ET during early stages of fruit growth showed reduced fruit size at that time. However, with applications of 150% ET during the final fruit growth stage, fruit size recovered. Adjusted fruit weight also correlated with measures of tree water status including midday leaf water potential and canopy temperature.

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Authors: , , and

This paper is contribution A-318 of Fruit Tree Research Station. We thank Y. Hase for advice. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be

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Fruit water loss significantly affects the quality of bell peppers. The objective of this study was to determine the effect of fruit weight, size, and stage of ripeness on the rate of water loss and permeance to water vapor. Fruit surface area/weight ratio decreased logarithmically with increases in fruit size, with smaller fruit showing larger changes in the ratio than larger fruit. Mean water loss rate for individual fruit and permeance to water vapor declined with increases in fruit size and as fruit ripeness progressed. Fruit surface area/weight ratio and rate of water loss were both highest in immature fruit and showed no differences between mature green and red fruit. In mature fruit, permeance to water vapor for the skin and calyx were 29 μmol·m–2·s–1·kPa–1 and 398 μmol·m–2·s–1·kPa–1, respectively. About 26% of the water loss in mature fruit occurred through the calyx. There was a decline in firmness, water loss rate, and permeance to water vapor of the fruit with increasing fruit water loss during storage.

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Abstract

Fruit growth and final size were greater on lightly cropped than on moderately heavily cropped cherry (Prunus avium L. cv. Buriat) trees. A wax-based antitranspirant (AT), sprayed 1 week before harvest, increased fruit size on both lightly and moderately heavily cropped trees. Although the lightly cropped AT-treated trees had the largest fruit at harvest, the response to AT was greatest on the moderately heavily cropped trees. Thus, AT can improve fruit grade-size, and probably monetary returns, particularly on heavily cropped trees. High rates of AT application, however, can adversely affect fruit appearance.

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Abstract

Repeatability of scoring and inheritance of 5 characters were studied in highbush type blueberry progenies in 2 years. In the repeatability study, fruit size, scar and plant vigor scores were more consistent than fruit firmness and color. Plant vigor scores were high and fruit scar scores were low both years. In the inheritance study, cultivars ranked similarly for each character by either their phenotypic score or general combining ability effects. Mean square variances of general combining ability were larger than specific combining ability for fruit size, firmness, color and plant vigor. Mean square variance of specific combining ability was high for fruit scar. Heritability estimates for blueberry were high for fruit size, moderate for fruit color, low for fruit firmness and scar and lower for plant vigor.

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Variability in fruit quality of citrus occurs among and within trees due to an interaction of several factors, e.g., fruit position, leaf: fruit ratio, and fruit size. By determining variability in fruit quality among i) fruit, ii) trees, iii) orchards, and iv) geographic locations where citrus is produced in Florida, optimal sample size for fruit quality experiments can be estimated. To estimate within-tree variability, five trees were randomly selected from each of three `Valencia' orange orchards in four geographic locations in Florida. Six fruit were harvested from each of two tree canopy positions, southwest top and northeast bottom; fruit were not selected or graded according to fruit size. °Brix and titratable acidity of juice samples were determined, and the °Brix: acid ratio was calculated. Statistical analysis of fruit quality variables was done using a crossed-nested design. The number of trees to sample and the number of fruit per sample were calculated. To estimate between-tree variability, 10 trees were randomly selected from each of three `Valencia' orange orchards from four geographic locations in Florida. Fifty-fruit composite samples were picked from around the tree canopy (0.9 to 1.8 m). Juice content, SSC, acid content, and ratio were determined. Using a nested design, the number of orchards and number of trees to sample were determined. There was greater variability in fruit quality among trees than within trees for a given canopy position; the optimal sample size when taking individual fruit samples from a given location and canopy position is four fruit from 20 trees. There was less variability in fruit quality when 50-fruit composite samples were used, resulting in an optimal sample size of five samples from three orchards within each location.

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Benzyladenine (BA), carbaryl (CB), daminozide (DM), and naphthaleneacetic acid (NAA) were applied postbloom, as fruitlet thinning agents, to mature `Empire' apple trees. Although fruit set and yield were similar for BA, NAA, and CB, BA-treated fruit were larger, indicating BA increased fruit size beyond the effect attributable to thinning. BA applied at 100 mg·liter–1 increased the rate of cell layer formation in the fruit cortex, indicating that BA stimulated cortical cell division. The maximum rate of cell division occurred 10 to 14 days after full bloom (DAFB) when fruit relative growth rate and density reached a maximum and percent dry weight reached a minimum. Cell size in BA-treated fruit was similar to the control. Cell division ended by 35 DAFB in the control and BA-treated fruit when percent dry weight and dry weight began to increase rapidly and fruit density changed from a rapid to a slower rate of decreased density. These data support the hypothesis that BA-induced fruit size increases in `Empire' apple result largely from greater numbers of cells in the fruit cortex, whereas the fruit size increase due to NAA or CB is a consequence of larger cell size.

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Mature fruit size and shape are important traits of most melon types. Our objective was to identify RAPD markers associated with major QTL affecting fruit weight, length, diameter and shape by means of bulked segregant analysis in an F2 population from the ananas melon cross of Deltex (larger fruit size) × TGR1551 (smaller fruit size). Clear separations for fruit weight, length, diameter, and shape between Deltex and TGR1551 were observed. Continuous distributions for fruit weight, length, diameter and shape were found in the F2 population indicating quantitative inheritance for the fruit traits. Significant positive correlations were detected between fruit weight and shape traits (r = 0.73 to 0.80). A significant positive correlation was observed between fruit weight and glucose (r = 0.35) or fructose (r = 0.25), whereas no correlation was noted between fruit weight and sucrose or total soluble solids. Two small and large bulks for fruit weight and shape were developed from F2 plants. A total of 240 primers were used to simultaneously screen between the small and large bulks, and between Deltex and TGR1551. Twenty-six RAPD markers were polymorphic for the small and large bulks. Ten markers were found to be significantly and consistently associated with fruit size and shape traits on the basis of simple linear regression. Of the 10 markers associated, four displayed an amplified DNA fragment in the small bulk, while six showed an amplified DNA fragment in the large bulk. The associated marker OJ07.350 explained 15% to 27% of the phenotypic variation for the fruit traits. These markers associated with QTL for melon fruit size and shape are expected to be useful in melon breeding programs for modifying fruit size.

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The effect of rootstock on the flowering and fruiting response of sweet cherries (Prunus avium L.) was investigated using 4-year-old branch units. The cherry rootstock Edabriz (Prunus cerasus L.) affected the flowering and fruiting response of `Burlat' sweet cherry compared to Maxma 14 and F12/1. Branches of trees on Edabriz had more flowers, more flowers per spur, more spurs, more fruit, higher yields, smaller fruit, and a reduced fruit set compared to the standard rootstock, F12/1. One-year-old branch sections had more flowers and fruit, higher fruit weight, and heavier fruit size compared to older branch portions.

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