Dormancy in sweet cherry (Prunus avium L.) under Mediterranean climatic conditions
2007
Ahmed Mahhou | Ahmed Oukabli
It is admitted that the lack of winter chilling is a limiting factor for the cultivation of temperate fruit trees in warm climates. Nevertheless, the characteristics of dormancy in sweet cherry under such conditions are still not fully understood. Therefore, and in order to contribute to the elucidation of these mechanisms, the objective of this work is to evaluate the dormancy of sweet cherry (Prunus avium L.) under the Mediterranean conditions of Meknes region (Morocco). Evaluation of dormancy behaviour of four varieties was made on the basis of a biological test, known as the « single node cuttings », and histological dissections of flower buds at the time of bud break. The variations of mean time to bud break (MTB) were interpreted in terms of the evolution of growth capacity of the buds. The lack of cold affected tree phenological development. The evolution of dormancy in cherry buds showed three phases with variable levels of inertia: the first and third phases being of similar intensity and duration while the second phase was of a high level of inertia (endo-dormancy). The correlative inhibitions of the leaves imposed on the buds continued up to the arrival of continuous low temperatures. The delay in the decrease of inertia reveals insufficient chilling accumulation causing incomplete release from dormancy and low bud break percentage in the orchard. Histological observations showed that vascular connection of flower buds was established during bud break stage. However, flowers showed certain abnormalities, ie low pollen production and malformations of pistils, which limit the possibilities of pollination.
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