Suitability of hydrogen cyanamide+oil application for dormancy overcoming in 'Early Maycrest' peach in a warm-winter climate.

摘要

Dormancy-breaking chemical agents are usually used to compensate insufficient chill accumulation that may cause severe production problems in fruit crops. In this study we evaluated if the application of DormexReg. and winter oil is efficient and suitable to enhance dormancy release in a southern Spain location. The treatment was tested at different phenological stages in the low chill peach 'Early Maycrest' (Prunus persica L. Batsch). Blooming and harvest times as well as blooming and fruit set percentages were evaluated during two consecutive years. The source of temperatures used to calculate chill accumulation (expressed as hours below 7 degrees C, Utah Model and Dynamic Model), obtained either from shade or sun, was also discussed. Trees were treated at two different phenological stages: ca. 50% and ca. 75% of the chilling requirements (CR) of the cultivar. The chill accumulated under field conditions was markedly different between years. The treatments only brought forward harvest time by 2 and 3 days in 2007 and 2008, respectively. However, no significant differences were found between different moments of application with regard to blooming and harvest dates and blooming and fruit set percentages. Also, no significant differences in blooming and fruit set percentages were found between the treated and control trees. The application of this treatment in extra-low-chill peach cultivars in our climatic conditions is not recommendable unless done after exceptionally warm winter conditions not fulfilling cultivar CR.