Proline and some enzyme changes in flower buds of some apricot cultivars during heat accumulation period

This experiment was conducted to evaluate the proline and enzymes changes after termination of chilling requirement and during heat accumulation. Four apricot cultivars including “Tabarzeh”, “Shekarpareh”,”Shamloo” and “Asgarabad” were selected at Khalaat Pooshan Agricultural Research Station, Tabriz University, Iran. In this study, changes in enzyme activity of catalase, peroxidase and superoxide dismutase as well as proline content were measured monthly just after the end of dormancy period until 50% blooming for each cultivar. Analysis of variance (ANOVA) showed that there was a significant difference in enzymes activity within different cultivars. Enzymes activity had the minimum value immediately after terminating chilling requirement while reached the maximum value during the bloom. Comparing the average superoxide dismutase, catalase and peroxidase activity in different cultivars showed that “Asgarabad“ had the highest enzyme activity in March with the 3254 Grow Degree Hour (GDH), while the least amount of enzyme activity was recorded in “Tabarze“ during February with 214 GDH. Also, significant change in proline content was revealed in studied cultivars at different sampling times, so that, the highest and lowest proline contents was observed in “Tabarzeh” with 254 GDH and “Asgaraabad” with 214 GDH, respectively.