The present study was carried out to study the variation of antioxidative potentials in terms of activities of antioxidative enzymes along with the accumulation of osmolytes and plant growth in the leaves of two groundnut (Arachis hypogaea L.) cultivars namely K-134 and JL-24 under three levels of water supply conditions. Growth retardation in terms of root and shoot length, and in relation to the severity of drought stress was more pronounced in susceptible cv. JL-24 than in in tolerant cv. K-134.The leaves of cv. JL-24 showed greater reduction in dry weight and relative water content (RWC) when compared to cv. K-134 with increasing stress intensity. The activities of antioxidative enzymes which include superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), glutathione reductase (GR) and osmolytes such as proline and glycinebetaine were significantly high in the water-stressed leaves of both cultivars and the magnitude of increase was dependent on the severity of stress. These results highlight the ability of groundnut cultivars to up-regulate the enzymatic antioxidant system and osmolytes to withstand oxidative during water deficit conditions. However, the extent of up-regulation varied between the cultivars K-134 and JL-24, leading to the higher amounts of antioxidants and osmolytes in cv.K-134, supporting its drought tolerance. Furthermore, the drought tolerant nature of cultivar K-134 was well supported by lower rates of membrane lipid peroxidation, electrolytic leakage and chlorophyll breakdown.
Key words: Groundnut, Antioxidants, Water stress, Drought tolerance, Osmolytes