Apricot Flower Bud Development and Fruit Set in Different Types of Shoots in 'Moniqui' Variety

Erratic fruit set is influenced by a number of environmental factors, but also the term flower quality has been coined to host internal uncontrolled factors. However, the main limitation to study flower quality is that it cannot be precluded a priori. In this work, apricot flower bud development has been studied in two types of shoots, the short shoots having a high fruit set ratio in relation to the long unproductive shoots. In both types of shoots, fruit set has been determined and the main drops of buds, flowers and developing fruits characterized. As expected, clear differences were recorded in the final fruit set between both types of shoots, but the pattern of drop was the same in long and short shoots, suggesting a common background behind the flowers that drop. Differences in fruit set were related to differences also in the pistil at flowering. Finally, flower bud development was sequentially examined from autumn to the next spring, paying attention to the anatomical and histochemical changes along this period. The population of flower buds and flowers from short shoots was always heavier and had higher starch content than the long-shoots at all the phenological stages from budbreak to anthesis. Results are discussed in terms of the involvement of the starch content of the flower bud in the reproductive success.