Physiological and antioxidative responses associated with drought tolerance of Lasiurus sindicus Henr. endemic to Thar desert, India

Sewan ( Lasiurus sindicus Henr.) is an endemic fodder grass of low rainfall sandy habitat of hot Indian Thar desert. To understand drought responses and tolerance mechanism in Lasiurus sindicus , seedling growth, root cell viability, changes in enzymatic antioxidants and oxidative injury were assayed at early stage of seedlings in polyethylene glycol (PEG) 6000 (5, 10 and 20%)-induced drought stress. The reduction of seed germination, seedling growth, relative water content and vigor index was found with high level of PEG (10–20%), while 5% PEG slightly increased the germination and the growth parameters. A decline in pigments (Chl a, Chl b, total Chl, carotenoids), chlorophyll stability index, membrane stability index and protein content was observed, which was correlated with increased level of malondialdehyde, an indicator of excess reactive oxygen species. Results showed that increasing level of PEG activated the antioxidative enzymes, superoxide dismutase, peroxidase and catalase. Non-enzymatic antioxidants (ascorbate, phenols) and accumulation of cytosolutes (proline and sugar) for regulation of growth, osmotic potential and reactive oxygen species in drought tolerance. Overall results showed that seeds have adaptive mechanisms for germination and growth under lower level of drought, while increasing drought stress reduced growth potential of L. sindicus. It exhibited drought tolerance features, enhancement in activity of antioxidative enzyme and cytosolutes accumulation which involved in regulation of oxidative damage and osmotic adjustment for survival of the seedlings. Furthermore, our results provide important information about the physiological and antioxidative responses of the seedlings and mechanism associated with drought tolerance of L. sindicus .