ISHS Acta Horticulturae 81: Symposium on Winterhardiness in Woody Perennials
THE EFFECT OF GIBBERELLIN APPLICATIONS AND DEFOLIATION DURING SUMMER ON COLD RESISTANCE OF APPLE TREES THE FOLLOWING WINTER |
| Author: | D.O. Ketchie |
| Abstract:
Gibberellic acid /GA3/ was applied to different "Golden Delicious" apple trees at weekly intervals during mid and late summer. Other apple trees were defoliated at weekly intervals during the same period. The cold resistance of the trees varied in relation to time of application of GA3 throught the winter. This response can be inhibited by less than 20°C and enhanced by temperature about 30°C. Defoliated trees were generally less cold resistant than trees not defoliated. The indication was there is possibly a mechanism in the trees during mid-summer that regulates the capability of the apple trees to acclimate to cold. | |
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