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Duane W. Greene

ProCa at 125 mg·L −1 with surfactant and water conditioner on 28 May and 18 July. On 29 May, initial fruit set counts were taken on all tagged limbs and fruit size measurements were taken on 30 randomly selected fruit per tree. At the end of June drop

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Hazel Y. Wetzstein, Zibin Zhang, Nadav Ravid and Michael E. Wetzstein

; Martinez et al., 2006 ). Despite the long history of pomegranate culture as a fruit crop, literature is lacking on how fruit characteristics and components relate to changes in fruit size. Pomegranate exhibits considerable phenotypic diversity in fruit size

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Elina D. Coneva and John A. Cline

The purpose of this research was to determine the effectiveness of three blossom-thinning compounds on crop density and fruit quality of two peach cultivars. Treatments consisted of 15 ml·L–1 and 30 ml·L–1 ammonium thiosulphate, 30 ml·L–1 and 40 ml·L–1 decyl alcohol, and 40 ml·L–1 lime sulfur. Treatments were applied to `Redhaven' and `Harrow Diamond' peach trees at two phenological stages: 80%, and 100% full bloom in 2002 and 2003. In both years, treatments reduced the crop density in both cultivars, and in 2003 the amount of hand thinning required to adjust the crop load was significantly reduced. Fruit size from several blossom-thinned treatments was comparable with that observed from hand-thinned trees. However, treatments caused significant leaf phytotoxicity to `Harrow Diamond' trees in 2003, likely a result of hand spray gun applications. These data indicate that chemical sprays at bloom can be used successfully to reduce fruit set, but are very environmentally, dose, and cultivar dependent.

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H.M. Wallace, B.J. King and L.S. Lee

Pollen source is known to affect the fruit size and quality of 'Imperial' mandarin, but no study has determined the appropriate orchard design to maximize the beneficial effects of pollen source. We determined the parentage of seeds of 'Imperial' mandarin using the isozyme shikimate dehydrogenase to characterize pollen flow and the effect on fruit size in an orchard setting. Two blocks were examined: 1) a block near an 'Ellendale' pollinizer block; and 2) an isolated pure block planting. Fruit size and seed number were maximum at one and three rows from the pollinizer (P ≤ 0.05). Isozyme results were consistent with all seeds being the result of fertilization by the 'Ellendale' pollinizer. In the pure block planting, fruits in rows 5-11 inside the block were very small with no seeds. This indicates poor pollen flow resulting in a reduction in fruit quality for the pure block. These results emphasize the importance of pollinizers in orchard design, and bees in orchard management. They suggest that each row should be planted no more than three rows from the pollinizer to maximize the benefits of the pollen parent in self-incompatible cultivars such as 'Imperial'.

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Ed Stover, Scott Ciliento, Monty Myers, Brian Boman, John Jackson Jr. and Max Still

Six trials were conducted to determine whether lower spray volumes or inclusion of different surfactants would permit adequate thinning of mandarin hybrids (Citrus reticulata hybrids) at a much lower cost per hectare. Sprays were applied using a commercial airblast orchard sprayer during physiological drop when fruitlets averaged 8 to 16 mm in diameter. Surfactant was always included at 0.05% v/v. NAA always reduced fruit per tree, increased fruit size, and decreased production of smallest size fruit. However, in only three experiments, contrast of all NAA treatments vs. controls indicated increased production of the largest (80–100 fruit per carton) and most valuable fruit. In four of five experiments, comparison of spray volumes of 600 (only examined in three of four experiments), 1200, or 2300 L·ha–1 demonstrated significant fruit size enhancement from all NAA applications. Most individual NAA treatments resulted in fewer fruit per tree, but there were no statistically significant differences between NAA treatments at different spray volumes. In only one of the four experiments, there was a marked linear relationship between spray volume and fruit per tree, yield, mean fruit size, and production of largest fruit sizes. The effects of surfactants (Activator, a nonionic, Silwet L-77, and LI-700) on NAA thinning were tested in both `Murcott' and `Sunburst'. In comparisons between Silwet L-77 and Activator surfactant, one experiment with `Murcott' showed greater fruit per tree and yield reduction from using Silwet, but with a smaller increase in production of largest fruit sizes, whereas in another `Murcott' experiment, Silwet L-77 reduced numbers of smaller fruit size with no increase in production of larger fruit. Based on these findings, current recommendations for NAA thinning of Fla. mandarins are use of spray volume of ≈1100–1400 L·ha–1 on mature trees with proportionally lower volume on smaller trees. These data appear to support use of a nonionic surfactant rather than other tested surfactants in NAA thinning of Florida mandarins. Because experience with NAA thinning of Florida citrus is limited, it is only recommended where the disadvantages of overcropping are perceived to substantially outweigh the potential losses from overthinning.

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Ed Stover, Mike Fargione, Richard Risio and Xiaoe Yang

Two years of field experiments were conducted in eastern New York to evaluate the efficacy of a multi-step thinning approach on reducing crop load (no. fruit per cm2 trunk cross-sectional area) and increasing fruit size of 'Empire' apple (Malus ×domestica Borkh.). Applications of Endothall (ET) at 80% bloom, NAA + carbaryl (CB) at petal fall (PF), and Accel™ + CB at 10 mm king fruitlet diameter (KFD), alone and in all combinations, were compared to a nonthinned control and to the application of NAA + CB at 10 mm KFD (commercial standard). In both 1996 and 1997, orthogonal contrasts indicated the multi-step treatment significantly increased fruit size, reduced cropload, and reduced yield compared to single applications. Effects on cropload of consecutive treatments were largely predicted by multiplying effects of individual treatments. Although all thinning treatments except for NAA + CB at PF in 1997 significantly reduced cropload, no single treatment thinned sufficiently to ensure good return bloom. Compared to NAA + CB at 10 mm KFD, multi-step thinning with NAA + CB at PF followed by Accel™ + CB at 10 mm KFD produced bigger fruits in both years, and resulted in a higher percentage of spurs carrying a single fruit in 1996. When fruit size was evaluated after removing the effect of cropload (cropload adjusted fruit weight), NAA + CB at PF, Accel™ + CB at 10 mm, and the two applied sequentially, resulted in greater cropload adjusted fruit weight than the nonthinned control in both years, whereas NAA + CB at 10 mm did not. Contrast analysis of treatments with and without ET showed no significant effect of including ET on fruit size, though total cropload was reduced at P = 0.10 and total yield was reduced (P = 0.03 in 1996 and P = 0.12 in 1997). No deleterious effects from multi-step treatments have been observed. All thinning treatments significantly increased return bloom in 1996 and 1997 compared to the control with little difference observed between treatments. Chemical names used: naphthalene acetic acid (NAA); 1-naphthyl-N-methylcarbamate [carbaryl (CB)]; 6-benzyladenine [BA (Accel™)]; 7-oxabicyclo (2,2,1) heptane-2,3 dicarboxylic acid [ET (Endothall™)]

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James W. Olmstead, Amy F. Iezzoni and Matthew D. Whiting

The mature cherry fruit is composed of a thin protective exocarp, a fleshy mesocarp, and an inedible stony endocarp (pit) surrounding the seed ( Esau, 1977 ). All three tissue types arise from the ovary, and the increase in fruit size results from

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Lisa Klima Johnson, Anish Malladi and D. Scott NeSmith

Fruit size is a commercially valuable trait in many horticultural crops, including rabbiteye blueberry. Sensory evaluations indicate a greater preference among consumers for large-sized blueberry fruit ( Donahue et al., 2000 ; Saftner et al., 2008

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Gregory A. Lang and Robert G. Danka

analyses, Jim Parrie for his suggestions and discussion, and Suzanne Lang for her assistance in fruit size measurements. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore

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Shaul Naschitz and Amos Naor

Water availability and crop load (number of fruit per tree) affect the fruit size of apple (Malus ×domestica Borkh.), but their interaction in relation to fruit size is not well understood. The objective of the present study was to explore the effect of crop load on water consumption of `Golden Delicious' apple in relation to fruit size. A wide range of irrigation rates and crop loads was applied to mature, field-grown `Golden Delicious' apple trees for two consecutive years, 1995 and 1996. The number of fruit, crop yield, and average fruit diameter were determined for each tree. A model was proposed to describe the combined effect of crop yield and irrigation rate on fruit size. In the model, irrigation waters were divided between two uses: vegetative water use (UV), which enables the tree to produce a steady, long-term yield; and reproductive water use (UR), which supports the production of the dry mass of commercial-size fruit. Potential fruit diameters were 77.1 and 72.2 mm for 1995 and 1996, respectively. Calculated vegetative use values were 300.2 and 323.4 mm for 1995 and 1996, respectively. The response of fruit diameter to reproductive water use per ton fresh weight (specific reproductive water use; URT) was fitted by a hyperbolic model in which the fruit diameter increases with increasing specific reproductive water use and approaches the yearly potential diameter at 60 to 70 m3·t-1, irrespective of the potential fruit diameter. In both years, fruit diameter showed a closer correlation with the specific reproductive water use than with either crop load or irrigation rate. In conclusion, the crop yield and the potential fruit size determine the irrigation rate required to achieve a certain average fruit diameter. The year's potential fruit diameter does not affect the total tree water use or its components. The proposed model can be used by growers for supporting decisions on irrigation and thinning strategies in commercial orchards.