Articles
BUD DORMANCY AND ADAPTATION OF APPLE TREE TO MILD WINTER CLIMATES
Dormancy dynamics under natural conditions were studied with the cultivar "Golden Delicious" grown in an orchard near Clermont-Ferrand (Central France). Only terminal buds exhibited deep dormancy from late September until mid-December, whereas axillary buds seemed to be inhibited simply by physiological correlations.
We also studied the action of different temperatures on the growth of isolated buds during deep dormancy, on the breaking of dormancy and on the elongation of vegetative buds during post-dormancy.
The influence of cold deprivation during autumn and winter was investigated on the apple cultivar "Royal Gala" ; the potted trees were transferred to an air-conditioned greenhouse (minimum temperature 15°C) after varying periods of exposure to ambiant cold temperatures.
We established dormancy dynamics under these conditions and compared them with those of trees maintained outdoors.
We showed that warm temperatures did not prevent the breaking of dormancy but delayed the production of leaves on the trees, the foliation being all the more variable as the trees were transferred earlier to the greenhouse.