ISHS Acta Horticulturae 662: VII International Symposium on Temperate Zone Fruits in the Tropics and Subtropics
INVESTIGATION OF THE EFFECTS OF LIGHT AND RAIN ON OVERCOMING OF DORMANCY IN SOME APPLE CULTIVARS |
| Author: | G.A. Finetto |
| Keywords: | Chilling Units, light, rain, chilling requirement, one year old shoot, spur |
| Abstract:
In the temperate plants the overcoming of the dormancy is mainly determined by the temperature. However, some authors have noted that the intensity of the light and the rain can determine some influences. In fact bud burst can delay or advance in relation to the intensity of these two factors. In order to know their actions better and especially in which moment of the growing season they affect, meteorological data (temperature, intensity of light and rain) were collected and the times of bud burst of three apple cultivars (Golden Delicious, Morgendurf and Summered) in two types of twigs were established during nine years (1992-2002). The temperatures for the overcoming of dormancy were valued as Chilling Units by Richardson’s model. Light and rain data were accumulated in relation to the following periods; from field bud break up to the overcoming of dormancy (bb-ed), from field bud break up to completed leaves fall of the shoots (bb-lf), from completed leaves fall of the shoots up to the overcoming of dormancy (lf-ed), and from October up to the overcoming of dormancy (Oct-ed). The uni-variables analyses have shown that the duration of dormancy (days) against rain accumulated had low negative correlations in nearly all the cases. Golden Delicious and Morgendurf showed the best results in the periods lf-ed. The duration of dormancy (days) against light accumulated had higher positive correlations in the cases related to the periods from lf-ed and Oct-ed. The multivariate analyses of the three factors have been performed and it has indicated that the interactions among Chilling Units, light and rain are higher when rain is heavy, the light is moderated and Chilling Units accumulated are low. It appears from this investigation that the rain and radiation can influence the overcoming of the dormancy when they are linked to the temperature. Their contribution is more useful for the overcoming of dormancy when both are considered together with Chilling Units than alone. | |
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