Drought response at early seedling stage of pearl millet
The study evaluates the impact of drought at an early seedling stage of pearl millet. Drought stress imposed for 7, 14 and 21d showed considerable changes in morpho-physiological attributes and inhibited root and shoot growth. After 14 and 21d of stress, there was a significant decline in total chlorophyll content with visible chlorosis lesions in leaves. This was followed by significant decline in biomass and relative water content after 7, 14 and 21d of stress. Drought stress raised the levels of ROS such as H2O2 and O2⸺ in root and shoot to a significant level along with increased rate of lipid peroxidation. In roots, the uptake of Evans blue dye indicated severe loss of plasma membrane integrity as a consequence of high ROS induced peroxidation of membrane lipids. With high ROS production, both enzymatic and non-enzymatic antioxidants are degraded. The activities of antioxidant enzymes such as CAT, GPx, GR and SOD under drought were significantly inhibited in root and shoot as compared to their controls. Similarly, non-enzymatic antioxidant such as AsA and GSH were significantly lowered under drought stress. Our results clearly revealed that pearl millet is highly susceptible to drought condition at an early seedling stage.