Spring frost damage in buds, flowers and developing fruits in apricot

Apricot (Prunus armeniaca L.) trees bloom early and frequently encounter periods of freezing temperatures from budbreak to fruit set. Thus, important damages are produced by low temperatures in buds, flowers and developing fruits, and crop losses due to frosts after dormancy are usually more important than those due to frosts during winter. In this work, freezing injuries associated with low temperatures during and after budbreak were studied under orchard conditions, for several years, in apricot 'Moniqui'. Symptoms in different phenological stages, from budbreak to several weeks after bloom, have been examined in the days following the frosts. Likewise, the evolution of the affected organs has been followed to establish the influence of the frosts on the fruit set and crop. At flower budbreak, while external symptoms were not observed, freezing temperatures caused clear internal damage. During the pre-bloom and bloom period, clear external and internal symptoms were observed in several floral structures in the days following the frost. Finally, in developing fruits, a clear relationship has been established among the early external symptoms observed in the epidermis in the first few days after the frost and the damage in the developing seed, the arrest of fruit growth and the subsequent fruit abscission