Four chickpea genotypes differing in their sensitivity to high temperature stress were taken and grown in growth chambers in the phytotron facility of IARI, New Delhi. The plants were maintained at 18/23°C (control) and 25/35°C (temperature stress) night/day temperature after maximum tillering. In all chickpea genotypes high temperature stress increased membrane injury index (MII), activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX), malic acid and slightly decreased the activity of glutathione reductase (GR), relative water content (RWC), chlorophyll and carotenoid contents. Under the HT stress, the tolerant genotypes Pusa-1103 and BGD-72 exhibited higher RWC, chlorophyll and carotenoid, activity of SOD, APX, GR and, and less decrease in MII as compared to susceptible genotypes Pusa-256 and RSG-991. Antioxidant enzymes showed positive correlation (r) with chlorophyll content, RWC and negative with MII under high temperature stress. From the results it is apparent that the antioxidant defence mechanism plays an important role in heat stress tolerance of chickpea genotypes
