To assess cytoplasmic membrane stability as an indirect criterion in draught tolerance selection in bread wheat, two separate experiments were carried out in Ardabil IAU Agricultural Research Station and Biotechnology and Tissue Culture Laboratory, in 2012. The research included 10 genotypes which were studied in randomized complete block design in 3 replications. Greenhouse experiment was conducted as a randomized complete block design in 3 replications in two phases of vegetation and reproduction Ardabil IAU Agricultural Research Station. The 3 stresses in this research induced osmotic stress by polyethylene glycol, osmotic atmospheric stress and heat stress by warm water on flag leaves of plants during vegetation and reproduction (before and after flowering). Stresses were applied to the plants and the damage to cytoplasmic membrane was measured. Results from analysis of variance on damage indices during phases of vegetation and reproduction under heat, osmotic atmospheric and osmotic stress by polyethylene glycol suggested that there is a little genetic diversity between genotypes (genotype differences was insignificant in some cases and in some other cases, differences was significant at 5%). Mean comparison results on membrane damage indices indicated that based on stress type and growth stage, genotypes order changes on membrane stability. However, it could generally be said that genotypes No. 3, 6, 9 and 4 have more stable membranes (it should also be mentioned that genotypes No. 3, 4 and 9 are among the most draught stress tolerant cultivars).
