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Ockert P.J. Stander, Graham H. Barry, and Paul J.R. Cronjé

Alternate bearing is a problematic phenomenon that occurs in certain fruit and nut trees. It is characterized by trees flowering profusely and producing an excess amount of fruit in one season, called an “on” season, followed by the production of a

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Craig E. Kallsen, Dan E. Parfitt, and Brent Holtz

Alternate bearing (alternating years with high and low yields) is a prominent characteristic of ‘Kerman’ Pistacia vera L., the primary California cultivar ( California Pistachio Commission, 2006 ; Monselise and Goldschmidt, 1982 ). Generally

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Charles T. Rohla, Michael W. Smith, Niels O. Maness, and William Reid

Alternate bearing is the most significant horticultural problem facing pecan producers. Studies have suggested that stored carbohydrate concentrations during the winter markedly affected subsequent flowering ( Malstrom, 1974 ; Smith and Waugh

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Lauren C. Garner and Carol J. Lovatt

excessive. Clearly, a strategy to reduce the abscission of reproductive structures would increase avocado yield. The reproductive phenology of many avocado cultivars, including ‘Hass’, is further characterized by alternate bearing. Alternate bearing is a

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Marisa Y. Thompson, Jennifer Randall, Richard J. Heerema, and Dawn VanLeeuwen

Alternate bearing (AB) poses a major challenge for the pecan [ Carya illinoinensis (Wangenh.) K. Koch.] industry ( Wood, 2003 ). AB refers to a tendency for wide season-to-season fluctuations in cropping intensity. This is often expressed as a

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Johannes S. Verreynne and Carol J. Lovatt

Alternate bearing (also called biennial or uneven bearing) is the tendency of a fruit tree to produce a heavy crop (on-crop year) followed by a light crop or no crop (off-crop year). The phenomenon is widespread, occurring in deciduous and

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Patrick J. Conner and Ray E. Worley

The Coastal Plain Experiment Station has been evaluating pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars for over 75 years. Using annual yield data from this program, the alternate bearing intensities (I) of 66 pecan cultivars and numbered U.S. Dept. of Agriculture (USDA) selections were determined. Values ranged from 0.19 to 0.93 in young trees, and from 0.27 to 0.91 in mature trees under high-input production practices. The adoption of fungicides, insecticides, and irrigation during the last 30 years has reduced the average I value from 0.70 to 0.55. I was negatively correlated with both nut yield and nut weight. All but one cultivar recommended for commercial production in Georgia have I values lower than the average of 0.57 for all cultivars in this test. Values calculated early in a tree's productive life cycle were highly correlated with those of mature trees.

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Marisa Y. Thompson, Jennifer J. Randall, Dawn VanLeeuwen, and Richard J. Heerema

Alternate bearing (AB) is the most important horticultural problem for the pecan ( Carya illinoinensis ) industry ( Wood, 2003 ). Alternate bearing in perennial tree crops comprises a propensity for “on” years of high fruit yield interspersed with

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Ockert P.J. Stander, Graham H. Barry, and Paul J.R. Cronjé

Alternate or biennial bearing in citrus ( Citrus sp.) is the synchronized tendency of a shoot, branch, or tree to flower profusely and produce an excessive number of fruit in one season followed by a few flowers and fruit in the following season

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Johannes S. Verreynne and Carol J. Lovatt

Alternate-bearing trees produce a heavy on-crop followed by a light off-crop. Whereas climatic events initiate alternate bearing, it is perpetuated by endogenous tree factors. For citrus, the mechanism and underlying physiology by which fruit influence floral intensity the next spring was unresolved. To determine whether reduced return bloom of on-crop trees was due to inhibition of vegetative shoot production and, thus, a lack of “wood” on which to bear next spring's inflorescences or, alternatively, to inhibition of phase transition and inflorescence development on an adequate number of vegetative shoots, fruit were removed from individual shoots monthly or from entire on-crop `Pixie' mandarin trees during periods critical to shoot initiation (summer) and phase transition (winter). Fruit removal provided clear evidence that the on-crop exerted a significant effect on return bloom during the summer by reducing summer–fall shoot growth and, hence, the number of flowers borne on these shoots as well as on old wood of fruit-bearing shoots. The on-crop had less effect in winter on phase transition and return bloom. Buds collected during the summer from on-crop `Pixie' mandarin trees were characterized by high indoleacetic acid and low isopentenyladenosine concentrations compared to buds from off-crop trees. The starch level of the buds was not affected. No differences in hormone concentrations were detected for buds collected during winter from on- and off-crop trees, but buds of on-crop trees had less starch. The results demonstrate that the on-crop reduces return bloom predominantly by inhibiting summer-fall vegetative shoot growth by a mechanism similar to apical dominance, not a lack of available carbohydrate.