physiological and biochemical responses of lines obtained from Norstar and Pishtaz wheat crossing to cold stress

Low temperature (LT) is one of the most important factors that limits growth, distribution and production in cereals. The purpose of the present study was to identify some traits related to LT tolerance in different phenological development stages in lines resulted from crosses between Pishtaz and Norstar wheat. Under experimental conditions, LT tolerance, shoot apex developmental, final leaf number (FLN), activity of antioxidant enzymes, total sugars and H2O2 contents were investigated. Results of double ridges formation and FLN showed that winter and facultative habit genotypes spent the longer time in the vegetative phase and entered the reproductive phase with delay. These genotypes also were more tolerant to LT in comparison to spring habit genotypes. Analysis of variance showed that genotypes, sampling period, and their interaction were highly significant for most of the traits. Ascorbate peroxidase (APX), guaiacol peroxidase (GPX), polyphenol oxidase (PPO), catalase (CAT), superoxide dismutase (SOD), and total sugars content reached their maximum in all genotypes at the second period of LT acclimation but higher in winter and facultative than spring habit genotypes.