Evaluation of cold tolerance of almond cultivars and genotypes in open flower stage

Late-spring frost and frost damage at the anthesis and fruit set stage is one of the main limiting factors in worldwide almond growing areas. Utilization of genetic potential is one of the effective strategies in reducing the damage of late-spring frost. According to this fact, this study was conducted to evaluate the response of different almond cultivars/genotypes to frost damage based on a lab experiment with temperature fall (-2.5°C) in the open flower stage. For this purpose, branches of 30 almond cultivars/genotypes with flower buds were used. At least 100 flowers of each cultivar/genotype with 3 replications were considered and data were recorded 24 h after frost treatment. The results showed that the severity of frost damage was influenced by almond genotypes. After evaluating the 30 almond selections, based on frost resistance, they were divided into high cold-resistant; medium cold-resistant; low cold-resistant, and very low cold resistance. Also, it was found that the genotypes that were more resistant to frost damage had less ion leakage. Therefore, ion leakage can be served as an indicator of frost tolerance in almond breeding programs.