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Fruit size is an important component of appearance quality and one of the important factors determining the economic value of fruit trees. Fruit size is determined by both cell size and cell number ( Breuninger and Lenhard 2010 ; Gonzalez et al

Open Access

Abstract

The relative decline in fruit size from primary to secondary to tertiary positions on the inflorescence of large-fruited clones was much greater than for small-fruited clones. Large-fruited clones produced fruit with more achenes and larger achenes than did small-fruited clones. Fruit weight was positively correlated with total achenes per fruit, developed achenes per fruit, mean weight of total and developed achenes, and fruit weight per developed achene. These results lead to the conclusion that fruit size differences among strawberry clones are due to the combined effects of developed achene number, developed achene size, differential activity of achenes in producing growth hormones and differential sensitivity of receptacular tissue in responding to growth hormones.

Open Access

Abstract

The dependence of fruit growth of grapefruit (Citrus paradisi Macf.) upon leaf area was investigated on girdled branches by manipulating leaf and fruit numbers. Leaf areas of 2.0 ± 0.5 m2 per fruit were found to be saturating with regard to fruit growth rate and size. Fruit on internal, shaded branches required larger leaf areas. Fruit on girdled branches weighed 44 to 119% more than fruit in ungirdled branches, which had leaf areas of 0.35 to 0.55 m2 per fruit. This indicates that leaf area is one of the factors limiting fruit growth. Starch accumulated in thin twigs during the fruit growth season, forming a saturation curve similar to those obtained for fruit size when plotted against leaf area per fruit. Increasing leaf area per fruit could involve a decrease in photosynthetic activity, a possibility which now is being investigated further.

Open Access

Abstract

The relationship between fruit size and extractable anthocyanins was investigated in 6 cranberry (Vaccinium macrocarpon Ait.) cultivars: Franklin, Ben Lear, Early Black, Crowley, Stevens, and Pilgrim. Extractable anthocyanins decreased linearly as fruit size, measured by fruit weight, of the sample increased. The relationship was especially apparent for dark-colored cultivars and the dark-colored berries within a cultivar. Results suggest that fruit size can contribute to the disparity between fruit color and extractable anthocyanins, and selection for larger-berried genotypes to increase yields may, concommitantly, reduce anthocyanin yield.

Open Access
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Abstract

Seed counts of 2 size grades from 3 fruit sizes were made from 30 fruits each of 21 rabbiteye (Vaccinium ashei Reade) cultivars and selections. Total seeds/berry ranged from 110 for ‘Briteblue’ to 28 for selection T-111. Generally, larger fruit had more total and large seeds than smaller fruit; however, this relationship was not constant for all cultivars. Total seed number and number of large seeds per fruit appear to be heritable.

Open Access

The butylglycol ester of 2,4-DP increased final fruit size in `Owari Satsuma' mandarin (Citrus unshiu Marc.). The response magnitude depended on the concentration applied and treatment date. When applied at the end of physiological drop, 50 mg·liter-1 was the most effective treatment for increasing fruit size. Peel density and firmness also were improved. Because no fruit thinning occurred, this auxin seemed to stimulate fruit growth. Chemical name used: 2,4-dichlorophenoxypropionic acid (2,4-DP).

Free access

Abstract

A multiple regression analysis of yields of ‘6718 VF’ tomato (Lycopersicon esculentum Mill.) from 11 field plots along an ambient ozone gradient in southern California indicated that ozone was responsible for a significant reduction in fruit size. Ozone dose accounted for 85% of the reduction in fruit size and was at least 3.3 times more important than any of the monitored meteorological variables in predicting the percentage of marketable fruit. High ambient ozone depressed production and caused a significant decrease in fruit size over time. A model describing the reduction in marketing container yield (% reduction = 0 + (.0232 x dose)) predicted a 50% reduction at a dose of 2000 pphm-hours > 10 pphm.

Open Access

Fruit size is a commercially valuable trait. Although several factors are known to affect fruit size in apple, insights into the molecular aspects of its regulation are lacking. Our research aims to understand fruit size regulation using a combination of approaches. Analysis of a large fruited mutant of `Gala', `Grand Gala' (GG), showed that it was 40% heavier than `Gala' at harvest. Increase in size of GG fruit was caused by an increase in the cell size apparent at full bloom. Flow cytometry revealed the presence of multiple levels of ploidy (up to 16C) in GG during early fruit development. Increase in ploidy of GG is hypothesized to be due to endoreduplication, a process normally absent in apple. Endoreduplication is a modification of the cell cycle where DNA replication is not followed by cell division, resulting in increased DNA content accompanied by increased cell size. To understand if the cell cycle is altered in GG, four key cell cycle regulators, MdCDKA1, MdCDKB1, MdCYCB2 and MdCYCD3 have been partially cloned from apple using RT-PCR and RACE. As cell number at the end of the cell division phase is correlated with fruit size at harvest, expression analysis of these genes can provide valuable insights into their role in the regulation of cell number and fruit size. Analysis of cell cycle gene expression in GG may provide key insights into the altered molecular regulation that leads to endoreduplication in the mutant. Parallel approaches being employed to study whether environmental and cultural factors regulate fruit size through an influence on the cell cycle will also be discussed.

Free access

Bell pepper (Capsicum annuum L.) cultivars were grown in nine Florida environments to evaluate phenotypic stability of marketable fruit yield (t-ha-') and mean fruit size (g/fruit). A stable cultivar excelled for a particular trait when grown in either favorable or unfavorable environments. A stable cultivar for a given trait was defined as one with an individual mean greater than the grand mean (mean of all cultivars) (x > X), a regression coefficient (b1) ≤ 1 (individual genotypic mean regressed against environmental means), nonsignificant deviation mean squares from regression (S2d), coefficient of linear determination (R2) > 0.50, and coefficient of variation (cv) < the pooled cv. `Ssupersweet 860', `Whopper Improved', and `Ranger' were stable for mean marketable fruit weights and fruit size, and `Ssupersweet 860' and `Whopper Improved' were stable for mean fruit size. Bell pepper cultivars were differentiated for phenotypic stability of yield and fruit size or adaptability to diverse environments. Therefore, through stability analyses, bell pepper plant breeders can identify cultivars or select advanced breeding lines that express adaptability for fruit yields or size to diverse environmental conditions or cultural practices.

Free access

Fruit size, number of receptacle cells, and mean cell size were determined throughout development of secondary fruit of three day-neutral strawberry (Fragaria ×ananassa Duch.) cultivars grown in a greenhouse. Cells were counted after enzymatic separation of receptacle tissue, and mean cell volume was estimated from cell count and receptacle tissue volume. Size of mature fruit was small (3.8 g) in `Tillikum', medium (11.5 g) in `Tristar', and large (15.6 g) in `Selva'. Fruit size was correlated with the number of achenes per berry. Mature fruit of `Tillikum' had a lower fruit fresh weight per achene and lower achene population density (achenes per square centimeter) than the larger-fruited cultivars. The average number of cells per mature fruit was 0.72 × 106, 1.96 × 106, and 2.94 × 106 for `Tillikum', `Tristar', and `Selva', respectively. The relative difference among cultivars in the number of receptacle cells was established by the time of anthesis. In all cultivars, cell division was exponential for 10 days following anthesis and ceased by the 15th day. Mean cell volume increased slowly during active cell division, but rose rapidly and linearly for 10 days after cell division halted. Mean cell volume of all cultivars increased > 12-fold after anthesis and was ≈ 6 × 106 μm3 in mature fruit. The genotypic variation in the size of mature fruit was not the result of large differences in either duration of cell division after anthesis or mean cell volume, but rather was primarily due to differences in the number of receptacle cells established by anthesis.

Free access