Freezing tolerance of wheat cultivars at the early growing season after winter

摘要

Cold stress is a worldwide abiotic stress in temperate regions that affects plant development and yield of winter wheat?(Triticum aestivum?L.)?cultivars and other winter crops.?This?study?was conducted?to evaluate?the effect of?freezing?stress?at the early?growing season?on survival and also the relationship between?resistances tofreezing stress at this stage with drought resistance after?postanthesis in eight Iranian bread wheat cultivars. An?experiment was laid out in a split–plot arranged in a randomized complete blocks design with three replications.?Under control treatment among?all?cultivars, Marvdasht?and?Chamran?cultivars?had the lowest grain?yield?andbiomass;?except these two cultivars there were no significant differences between others. Postanthesis water stress caused more reduction in grain yield of Zarin, Phishgam and Marvdasht and biomass of Phishgam and Parsi cultivars, respectively. The lowest and highest LT50 temperatures of crowns at the early growing season were seen in Marvdasht (-4°C) and Pishtaz (-1.13°C) cultivars, respectively. Correlation coefficients of soluble and insoluble sugars concentration between crown survivals under freezing stress were, respectively positive and negative.?Grain yield under postanthesis water stress had the highest correlation coefficient?(R=-86.2%)with crown survival under freezing stress at the?early?growing season. Therefore,postanthesis water stress-sensitive?cultivars?were?more resistant?to?freezing?stress at the beginning of growing season after the cold of winter.