Stress induced injury and antioxidant enzymes in relation to drought tolerance in wheat genotypes

The role of plant antioxidant system in water stress tolerance was studied in three contrasting wheat genotypes. Water stress imposed at different stages after anthesis resulted in a general increase in lipid peroxidation (LPO) and decrease in membrane stability index (MSI), and contents of chlorophylls (Chl) and carotenoids (Car). Antioxidant enzymes like glutathione reductase and ascorbate peroxidase significantly increased under water stress. Genotype C 306, which had highest glutathione reductase and ascorbate peroxidase activity, also showed lowest LPO and highest MSI, and Chl and Car contents under water stress in comparison to susceptible genotype HD 2329, which showed lowest antioxidant enzyme activity as well as MSI, Chl and Car contents and highest LPO. HD 2285 which is tolerant to high temperature during grain filling period showed intermediate behaviour. Thus, the relative tolerance of a genotype to water stress as reflected by its comparatively lower LPO and higher MSI, Chl and Car contents is closely associated with its antioxidant enzyme system.