Abstract

                                All abiotic stresses lead to evolution of oxidative stress. Relatively, research addressing the physiological basis of oxidative stress tolerance are scanty. Hence, the study was designed to induce oxidative stress, by in vivo treatment with hydrogen peroxide (H2O2) in rice genotypes showing contrasting behavior to flooding and salt stress. Four genotypes namely, FR 13A (tolerant to flooding stress); Co 43 (susceptible to flooding stress); FL 478 (tolerant to salinity stress) and IR29 (susceptible to salinity stress) were taken to study important physiological traits like chlorophyll contents, cell Membrane Stability (CMS), lipid peroxidation, soluble sugars, Soluble protein content and Nitrate reductase (NR) activity under oxidative stress. The flooding and saline tolerant genotypes showed a lesser per cent reduction in the chlorophyll contents and were able to maintain higher sugar contents on exposure to H2O2 treatments compared to the susceptible ones. Degradation of protein contents and reduction in CMS with increased lipid peroxidation was observed in all the varieties and the protein contents decreased with increase in concentration of H2O2 treatment. H2O2 treatments also showed a linear decrease in NRase activity in all the genotypes taken for study.

Key words : Chlorophyll, Cell Membrane Stability, Lipid peroxidation, Soluble protein content, Soluble sugars, Nitrate reductase activity.