ISHS Acta Horticulturae 239: VI International Symposium on Growth Regulators in Fruit Production
THE ROLE OF ENDOGENOUS HORMONES IN SHOOT EMERGENCE AND ABSCISSION IN ALTERNATE BEARING VALENCIA ORANGE TREES |
| Authors: | J.A. Plummer, M.G. Mullins, J.H. Vine, R.P. Pharis |
| Abstract:
Alternate bearing is a problem in the production of Valencia oranges. In a sparse-flowering spring flush few floral shoots emerged and the light crop which ensued did not inhibit subsequent flowering. Many vegetative shoots emerged, however, and thus many buds were available for future shoot production. In the next spring, many floral shoots but few vegetative shoots were produced. Half of these floral shoots abscised from the tree and this was correlated with high endogenous abscisic acid levels. The remaining floral shoots gave rise to a heavy crop of fruit. Gibberellins (GAs) were found in high concentrations in pedicels. It is suggested that these high GA concentrations may be responsible for the inhibited shoot emergence and reduced floral initiation that occur on branches bearing heavy loads of fruit. | |
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