Evaluation of Cold Stress Tolerance and Some Agronomic Characteristics of Bread Wheat Promising Lines

To evaluate the cold tolerance potential of bread wheat promising lines, an experiment was conducted based on the alpha-lattice design with two replications during 2015-16 at the Seed and Plant Improvement Institute, Karaj, Iran. In this study, 16 promising lines obtained from the adaptation trial of temperate agro- climatic zone, and 12 promising lines obtained from the adaptation trial of cold agro- climateic zone, were evaluated for cold stress tolerance using an integrated method (laboratory and field). The cold-acclimated plants were sampled from the field in the early January 2015, and the potential of cold strss tolerance in plants was determined by measuring LT50 (the temperature at which 50% of plants are killed) using a regulatable freezer. The results showed that among the temperate adapted lines, eight lines and cv. Baharan had a lower LT50 than Parsi (check cultivar) with LT50 = -6°C and the lowest LT50 (-12°C) was related to line M-94-7. Among the cold adapted lines, eight lines had a lower LT50 than Mihan (check cultivar) with LT50 = -12°C and the lowest LT50 (-15°C) was related to lines C-94-11 and C-94-13. Cold stress tolerance in cultivars Heydari (-9.5°C) and Orum (-11.5°C) was lower and in Zarea (-13°C) was more than the cv. Mihan. Six lines from temperat agro- climatic zone and nine lines from cold agro- climatic zone had lower LT50 (cold tolerance), and higher grain yield than Parsi and Mihan, respectively.