Effect of NaCl stress on photosynthesis characteristics and antioxidant enzymes in rice cultivars

The effect of NaCl stress on physiological and biochemical characteristics of salinity tolerant CSR 27 and sensitive Pusa Basmati 1 rice cultivar was studied in comparison with CSR10. Thirty-five days old seedling was transplanted in earthen pots with three level of salinity stress (0, 6.0 and 12.0 dSm⁻¹) treatment. Observations were recorded for the rate of photosynthesis (P_N), chlorophyll content, relative water content (RWC) and antioxidant enzymes viz. Superoxide dismutase (SOD) and Catalase (CAT) were determined at 35 and 65 days after transplanting. Rate of photosynthesis and chlorophyll content decreased marginally by NaCl stress in CSR 27 and CSR10 but Basmati 1 showed greater reduction. CSR 10 and CSR 27 maintained higher RWC under NaCl stress compared to sensitive Pusa Basmati 1. SOD activity was highly induced under NaCl stress in CSR10 but CAT activity decreased. In CSR 27, induction of SOD and CAT activities was higher than that of Pusa Basmati 1. The results indicate that maintenance of higher RWC and induction SOD activity under NaCl stress in CSR 27 contributed to its salt tolerant characteristics.