ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
GIBBERELLINS AND REPRODUCTIVE DEVELOPMENT OF TREE FRUITS AND GRAPES |
| Authors: | N.E. Looney, R.P. Pharis |
| Abstract:
There are now many uses for exogenously applied gibberellins (GAs) in tree fruit and grape production and most involve an effect on reproductive development. The GAs now available for commercial use are GA3 and GA4+7 mixture. Floral initiation is frequently suppressed by GA3 and GA4+7 sprays but there is now evidence that GAs differ with regard to their effects on inhibition of floral initiation and that some may even promote flower initiation. Developing flowers are often rich in GA activity, as are the developing seed and young fruit, and endogenous GAs appear to play a role in normal development of these organs. Pollen is also rich in GA activity and pollen germination and pollen tube growth may be under GA control. However, while exogenously applied GAs promote parthenocarpic fruit set, apparently replacing the effect of pollination and/or fertilization on ovule development and early fruit growth, their role(s) as endogenous growth substances during natural fruit set and early fruit growth is still not clear. Likewise, while there are many commercially important uses for GAs to improve fruit condition, quality and even size, little is known about how these effects are achieved, or whether endogenous GAs function in the same way. | |
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