ISHS Acta Horticulturae 395: Dormancy and the related Problems of Deciduous Fruit Trees
NEW ASPECTS OF BUD DORMANCY IN APPLE TREES |
| Authors: | T. Bubán, M. Faust |
| Keywords: | Malus domestica, chilling, flower bud differentiation, endodormancy, nitrogen fertilization, Nuclear Magnetic Imaging |
| Abstract:
Inflorescence primordia within buds of apple trees continue to differentiate and enlarge during the winter. From the beginning of December to mid February the diameter of terminal flower primordia increased by 16 to 17%, and the lateral primorda by 6 to 18%. Growth was considerably more from mid February to mid March and averaged from 111 to 138% and 115 to 127% for terminal and lateral flowers, respectively. The state of water in buds was measured by determining relaxation times of water with magnetic resonance imaging (MRI). Results indicate that during endodormancy water is in the bound form. Bud growth during the dormant period indicates that in reality buds are not dormant because their primordia actively enlarge and their structure becomes more complex. Furthermore, this study indicates that bound water will not completely prevent growth; it perhaps only limits cell expansion on a larger scale. MRI studies revealed that the cambial layer retains free water during dormancy, and there are indications that there is free water in the center of the primordia. Perhaps better resolution with MRI will reveal areas of the primordia which have free water and are able to enlarge during dormancy. | |
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