Evaluation the Resistance of Almond Cultivars to Spring Frost at different Phenological stages

摘要

Almond cultivation was restricted to regions with low risk of spring frosts. Spring frost is a limiting factor for yield and its stability and for almond production and very little is known about frost susceptibility of almond cultivars. Therefore Shoots with flowers in three phenological stages (popcorn, flowering and young fruit) were harvested from three almond cultivars then frost treatment were applied in each stage separately. Frost damage of ovary, proline, ion leakage, peroxidase and catalase measurements were evaluated. The results showed that the most resistant cultivar to spring frost was 6-8 cultivar. Among all cultivars and different phenological stages the highest proline amount was in 6-8 cultivar and the lowest rate was in Shahroud 12 cultivar. The most peroxidase activity was observed in Shahroud 12 cultivar in popcorn stage at -0.5 ?C. Among different cultivars the highest catalase(CAT) activity was in flowering stage while in Shahroud 12 cultivar in popcorn stage CAT activity was the highest. The highest amount of ion leakage in Shahroud 12 cultivar in popcorn stage at -5 and -7 ? C was occurred. As a general result, among all of cultivars, 6-8 was the most resistant cultivar to spring frost damage.