Apricot flower bud dormancy: main morphological, anatomical and physiological features related to winter climate influence.

This review examines recent advances regarding flower bud dormancy in apricot, focusing on biological, anatomical, and physiological processes which occur during the induction and depth of dormancy. In a scenario of global climate change, the relationship between endodormancy and winter climate influence is discussed. Dormancy regulation is a complex process necessary for plant survival and development. In fruit species, the knowledge of mechanisms controlling dormancy and establishing its release appears crucial for successful yields. Specific studies have suggested that, when the flower buds are apparently inactive, slow and gradual changes occur in the whorls: organogenesis, such as microsporogenesis processes and vascular connections take place during the entire dormancy period. It has been indicated that an asynchronism between biological (i.e. endodormancy release, microsporogenesis evolution), anatomical (i.e. xylem vessel differentiation) and biochemical (i.e. changes in metabolic compounds and enzymes) events could represent further causes determining an inconstant rate of blooming. Temperature is the main factor involved in dormancy triggering and releasing. In the perspective of global warming, mild winter temperatures could greatly impact apricot ecological cropping systems. Phenological process-based models are considered to be the best tool to study the climatic changes and subsequent expected phenology variation (dormancy and flowering). A new model, calibrated and validated on apricot cultivars, is proposed to predict the dormancy release date in a future scenario.