عنوان مقاله [English]
In this research, cold tolerance of seven commercial grape cultivars including ‘Khalili’, ‘Bidaneh Qermez’, ‘Fakhri’, ‘Rishbaba’, ‘Thompson seedless’, ‘Yaghuti’ and ‘Ruby seedless’ was evaluated. Likewise, the relationships between biochemical and physiological responses of these cultivars with their cold tolerance were studied. For this reason, one-year potted vines were exposed to different temperatures: 25, 4, 0 and -4 ˚C. The highest cold tolerance at -4 ˚C was seen in ‘Khalili’ followed by ‘Fakhri’ and ‘Bidaneh Qermez’, while the lowest tolerance was observed in ‘Ruby seedless’ and ‘Thompson Seedless’. There were strong correlations between, previously reported, freezing tolerance of these cultivars during the winter and their cold tolerance at -4 ˚C; however, weaker relationships with cold tolerance at 4 ˚C were observed. Low-temperature treatments resulted in higher concentrations of soluble carbohydrates, proline, soluble proteins and hydrogen peroxide, but lower total chlorophyll and relative water content in all cultivars. Cold tolerant cultivars: ‘Khalili’, ‘Fakhri’ and ‘Bidaneh Qermez’ contained the highest relative water content, soluble carbohydrates, soluble proteins and total chlorophyll, but the least proline and hydrogen peroxide content. However, the highest proline and hydrogen peroxide was seen in cold-sensitive cultivars, ‘Ruby seedless’, ‘Thompson seedless’ and ‘Yaghuti’. The highest correlations between cell membrane stability of cultivars and their biochemical and physiological responses were observed at -4 and zero ˚C showing that plants activate their protective systems following temperature decrement down to a critical limit.