Assessment of Spring Frost Tolerance in Almond Cultivars and Genotypes Using Thermal Analysis

The blossoming of almond trees often coincides with spring frosts, significantly increasing the risk of reducing or even nullifying yield. However, there is genetic variability in their response to very low temperatures and frost. Therefore, identifying resistant cultivars and genotypes through reliable evaluation methods and utilizing their genetic potential is an effective strategy to overcome spring frost damage. Accordingly, this study investigated the response of different almond cultivars/genotypes to frost damage using controlled freezing and thermal analysis. For this purpose, two experiments were conducted separately in ۲۰۱۹ and ۲۰۲۰. The first experiment adopted thermal analysis to assess the spring frost tolerance of six almond genotypes (S۱, S۲, A۵, A۸, A۱۱, and A۲۳) at three phenological stages (green tip, popcorn, and open flower). The second experiment used thermal analysis, visual inspection, and ion leakage to examine the spring frost tolerance of ۲۶ cultivars/genotypes in ۲۰۱۹ and ۳۰ in ۲۰۲۰ at the open flower stage under a controlled temperature chamber. The research findings demonstrated that the phenological stage and cultivars/genotypes significantly influenced the exotherm temperature of the almond flower buds. The positive correlation between the exotherm temperature of the flower and leaf buds, frost damage, and ion leakage indicated that thermal analysis could be a practical tool for assessing frost tolerance in almonds. Based on the thermal analysis, the cultivars/genotypes D۱۲, Saba, KD۱۰۱, KD۹۹, A۵, and C۱۶ have been identified as top candidates for future almond breeding programs.

کلیدواژه ها:

abiotic stress ، Bud exotherm ، Exotherm analysis ، Flower hardiness ، Frost damage