Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 53 1 2022 03 21 Physiological and biochemical responses of lines obtained from Norstar and Pishtaz wheat crossing to cold stress Physiological and biochemical responses of lines obtained from Norstar and Pishtaz wheat crossing to cold stress 235 250 88233 10.22059/ijfcs.2021.318439.654802 FA Mohsen Hosseini Department of Agronomy and Plant Breeding, College of Agriculture and Natural Resources, University of Tehran, Iran. Reza Maali-Amiri Department of Agronomy and Plant Breeding, College of Agriculture and Natural Resources, University of Tehran, Iran. 0000-0003-2496-4800 Siroos Mahfoozi Cereals Research, Department of Seed and Plant Improvement Institute, Karaj, Iran Abbas Saidi Department of Plant Sciences and Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran Yasin Khaledian Department of Agronomy and Plant Breeding, University College of Agriculture and Natural Resources, University of Tehran, 31587-77871 Karaj, Iran Journal Article 2021 02 11 Low temperature (LT) is one of the most important factors that limit growth, distribution and production of 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 development, 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 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 genotypes. Analysis of variance showed that genotypes, sampling period, and their interaction were highly significant for the 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 genotypes. The highest H₂O₂ content observed at the third period of LT acclimation was the highest in spring compared to winter and facultative genotypes. The significant correlations coefficients for antioxidative activities and sugar content with lethal temperature 50 (LT₅₀) suggest that they could be useful as indirect indices for LT tolerance in wheat. The results of this study showed that vernalization required genotypes had a higher potential for LT tolerance when the traits associated with LT tolerance in vegetative stage are adjusted. Low temperature (LT) is one of the most important factors that limit growth, distribution and production of 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 development, 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 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 genotypes. Analysis of variance showed that genotypes, sampling period, and their interaction were highly significant for the 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 genotypes. The highest H₂O₂ content observed at the third period of LT acclimation was the highest in spring compared to winter and facultative genotypes. The significant correlations coefficients for antioxidative activities and sugar content with lethal temperature 50 (LT₅₀) suggest that they could be useful as indirect indices for LT tolerance in wheat. The results of this study showed that vernalization required genotypes had a higher potential for LT tolerance when the traits associated with LT tolerance in vegetative stage are adjusted. https://ijfcs.ut.ac.ir/article_88233_eb7809549ba835e16881e0285a68c145.pdf