Evaluation of winter cold tolerance and Critical temperature (LT50) estimation in 21 strawberry cultivars

Freezing injury of strawberry plants is one of the greatest factors reducing crop yield and quality in temperate regions. In order to evaluate the winter cold tolerance of 21 strawberry cultivars, an experiment was carried out based on randomized complete block design with three replications under natural freezing temperatures in agricultural research station of Ghamlou, part of agricultural research center of Kurdistan. Crown freezing injury index (It) based on electrolyte leakage as well as leaf and crown LT50 values, crown tissue browning intensity, survival percent, number of leaf/plant, leaf area, petiole length and yield/plant of strawberry cultivars were meseaured. There were significant differences (P≤0.01) between cultivars for all of the evaluated traits. The least crown freezing injury and the highest winter survival percent were seen in ‘Krasnyy bereg’, ‘Queen Elisa’, ‘Aliso’, ‘Dachnitsa’ and ‘Kurdistan’, respectively whereas ‘Tennage Beauty’ and ‘Selva’ showed the least tolerance to low temperatures. According to the results of probit analysis of crown critical temperature (LT50), ‘Krasny Bereg’ was the most tolerant cultivar to low temperatures while ‘Tennessee Beauty’ was the most sensitive cultivar compared to the other tested cultivars. Leaf area and petiole length had positive correlations with crown It and crown LT50 whereas the number of leaf/plant had a positive correlation with survival percent and yield/plant under low temperatures stress. Based on the results, the ʻQueen Elisaʼ compared to other varieties is the most appropriate cultivar for cultivation in cold regions.