Tolerance of drought and temperature stress in relation to increased antioxidant enzyme activity in wheat

An experiment was conducted with three wheat genotypes differing in their sensitivity to moisture and/or temperature stress to study the relationship of the chloroplast antioxidant system to stress tolerance. Both moisture stress and temperature stress increased glutathione reductase and peroxidase and decreased membrane stability, chlorophyll content and chlorophyll stability index in all genotypes. Under moisture stress, DL 153-2 showed the highest membrane stability index, chlorophyll content, chlorophyll stability index, glutathione reductase activity and peroxidase activity. However, under elevated temperature conditions, HD 2285, and to a lesser extent DL 153-2, showed higher membrane stability, chlorophyll content and chlorophyll stability index and activities of glutathione reductase and peroxidase. Raj 3077, which is sensitive to both drought and temperature stress, showed the lowest membrane stability, chlorophyll content and chlorophyll stability index and glutathione reductase and peroxidase activity under elevated temperature as well as drought conditions. Thus, it can be concluded that tolerance of the genotype to moisture and/or temperature stress is closely associated with its antioxidant enzyme system.