Analysis of the Modulation of Dormancy Release in Almond (Prunus dulcis) in Relation to the Flowering and Ripening Dates and Production under Controlled Temperature Conditions

Abstract

In this study, the control of eco- and endo-dormancy release led to the modulation of the flowering time in almond (Prunus dulcis (Mill.) D.A. Webb). The study was performed in almond cultivars with contrasting flowering times: the extra-early flowering cultivar Desmayo Largueta and the ultra-late cultivar Tardona. Temperature control in the “Autumn”, “Winter” and “Spring” chambers successfully delayed the flowering time in Desmayo Largueta. Advance flowering in the cultivar Tardona was limited, however, even with the application of sufficient chill in the Winter chamber. The ecodormancy period and the heat accumulation for flowering were not stable among cultivars, even though the heat accumulation was generally high, in accordance with that accumulated in field conditions. The heat requirements of the early cultivar Desmayo Largueta were lower than those of the ultra-late cultivar Tardona. We observed a decreasing pattern in ecodormancy along treatments that was probably related to the temperature in the Spring chamber. Finally, flowering and fruit set were highly variable, and these parameters were more dependent on the cultivar assayed than on the treatment applied. Although the ripening time under our experimental conditions was earlier than the phenological dates observed in the field, the flowering time delayed the ripening time in the case of the extra-early cultivar Desmayo Largueta. The fruit weight increased in the last treatments, whereas the kernel/fruit ratio decreased, as the kernel weight did not vary significantly along treatments. The results obtained show that flowering time can be modulated by temperature control and that other uncontrolled factors, such as photoperiod, can be involved in the control of endodormancy release and flowering time, especially in late flowering cultivars.