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Soon-Il Kwon, Jeong-Hee Kim, Sun-Ae Kim, Young-Soon Kwon, and Jinwook Lee

during long-term cold storage. ‘RubyS’ showed strong resistance to the most serious apple pests and diseases as does ‘Alpsotome’ cultivar and is self-thinning as well. Overall, the results indicated that tree characteristics and fruit quality of ‘RubyS

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Warren C. Micke, Joseph A. Grant, Maxwell V. Norton, and James T. Yeager

Under California conditions `Granny Smith' apple does not “self-thin” sufficiently to promote good return bloom nor to provide fruit size desired for the fresh market. Preliminary studies conducted during 1985-87 indicated that 1-naphthyl N-methylcarbamate (carbaryl), 1-naphthaleneacetic Acid (NAA), and 1-naphthaleneacetamide (NAD) could be useful for thinning `Granny Smith'. Detailed studies conducted in 1988 and 89 using dilute handgun applications demonstrated that all 3 materials provided reasonable thinning as shown by fruit set counts. NAA and NAD tended to slow fruit growth as compared to carbaryl. Carbaryl tended to uniformly thin clusters while NAA and NAD were more likely to remove all the fruit from some clusters and few fruit from others, especially in 1988. Compared to the control, all materials applied in 1988 improved return bloom in 1989 with carbaryl having a slightly greater effect than NAA and NAD. As a result of these studies carbaryl at 1.7 to 2.2 kg (active ingredient) per ha as a dilute application is being suggested for grower trials in California.

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Warren C. Micke, Joseph A. Grant, Maxwell V. Norton, and James T. Yeager

Under California conditions `Granny Smith' apple does not “self-thin” sufficiently to promote good return bloom nor to provide fruit size desired for the fresh market. Preliminary studies conducted during 1985-87 indicated that 1-naphthyl N-methylcarbamate (carbaryl), 1-naphthaleneacetic Acid (NAA), and 1-naphthaleneacetamide (NAD) could be useful for thinning `Granny Smith'. Detailed studies conducted in 1988 and 89 using dilute handgun applications demonstrated that all 3 materials provided reasonable thinning as shown by fruit set counts. NAA and NAD tended to slow fruit growth as compared to carbaryl. Carbaryl tended to uniformly thin clusters while NAA and NAD were more likely to remove all the fruit from some clusters and few fruit from others, especially in 1988. Compared to the control, all materials applied in 1988 improved return bloom in 1989 with carbaryl having a slightly greater effect than NAA and NAD. As a result of these studies carbaryl at 1.7 to 2.2 kg (active ingredient) per ha as a dilute application is being suggested for grower trials in California.

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Eliezer E. Goldschmidt

Carbohydrates fulfill several roles in plants; as building stones, as a source of energy, and also, as recently demonstrated, as modulators of gene expression. Primary, photosynthetic production of carbohydrates (as well as their release from tree reserves) is linked with the carbohydrate-consuming processes through complex feedback and feedforward regulatory loops. With horticultural productivity as the goal, maximum resources must be diverted toward reproductive processes. Persistence of viable vegetative structures must be secured, however, to enable the function of tree systems and ensure the tree's potential for future years. Thus, in the carbohydrate resource allocation of fruit trees, a delicate balance must be maintained between the vegetative and reproductive needs. Flowering, fruit set, and fruit enlargement have been identified as three distinct, critical stages within the annual course of yield formation in citrus. While each of these stages has its own, salient developmental features, all require considerable amounts of energy and their occurrence is dependent, at least to some extent, on the availability of carbohydrates. Whereas flower bud differentiation may require only a threshold level of carbohydrates, floral development and anthesis consume large amounts of carbohydrates due to the very large number of flowers per tree and their high rates of respiration. Fruit set is more closely linked to carbohydrate levels. Fruitlet abscission acts as a self-thinning, feedback mechanism to adjust the tree's fruit population to the carbohydrate supply. This mechanism does not operate properly in certain mandarin cultivars, resulting in alternate bearing. The acquisition of fruit size appears to be most directly correlated with the availability of photosynthate. Elimination of alternative sinks by extreme thinning and girdling brings about tremendous increases in fruit size. The fruit's vascular system also expands in response to the increase in photosynthate availability. A dynamic model has been constructed to provide a quantitative analysis of citrus trees' carbon balance during the annual productivity cycle.

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Griffin M. Bates, Sarah K. McNulty, Nikita D. Amstutz, Victor K. Pool, and Katrina Cornish

, Table 1 ). As expected, the extent of “self-thinning” increased significantly with planting density (increased competition), with only 32.8% remaining in the highest density by the 6-month harvest. However, the number of surviving plants still increased

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Julie R. Kikkert, Stephen Reiners, and Beth K. Gugino

year. The percentage of plant loss increased with seedling density, but higher seeding rates nevertheless produced more roots ( Table 1 ). A similar “self-thinning” of beet seedlings over time was reported by Benjamin et al. (1985) . However, in other

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Bruce W. Wood, Leonardo Lombardini, and Richard J. Heerema

mild alternate-bearing intensities in commercial orchards ( Conner and Worley, 2000 ), which is attributed to a major Stage II drop of developing fruit (commonly referred to as self-thinning). Although the magnitude of Stage II drop in ‘Desirable’ may

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Eliezer E. Goldschmidt

photosynthate ( Goldschmidt, 1999 ). Most orange and grapefruit cultivars have an effective self-thinning mechanism that adjusts the number of remaining fruit to a tree’s fruit bearing potential. The natural thinning mechanism, i.e., fruitlet abscission, appears

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Thomas Björkman and Joseph W. Shail Jr.

same time as buckwheat. In the NT treatments, there was no loss of plants during vegetative growth ( Table 1 ) because of self-thinning or root rot and no reduction in seedling emergence ( Table 2 ). The NT buckwheat produced only half as much dry

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Michael F. Polozola II, Daniel E. Wells, J. Raymond Kessler, Wheeler G. Foshee, Amy N. Wright, and Bryan S. Wilkins

regardless of self-thinning in a nonirrigated orchard. Furthermore, irrigation might ameliorate the tendency of P in ‘Desirable’, but that comes with the tradeoff of steady use of the nutrient. The 4× application rate was required in the nonirrigated orchard