Changes in Antioxidant Status, Water Relations and Physiological Indices of Maize Seedlings under Drought Stress Conditions

摘要

Background and Objectives: Continuously changing climate and drought stress is drastically affecting maize crop ecology. Drought stress at seedling stage disturbs the normal physiological plant functions and results in stunted growth. In present study the maize seedlings were tested to evaluate their stress tolerance against water limiting conditions through fluctuations in antioxidant defense mechanism, physiological responses and changes in plant water relations. Materials and Methods: Maize seedlings were exposed to drought stress at 3 levels (15, 25, 35%) induced by polyethylene glycol 6000 (PEG-6000), under controlled conditions with completely randomized design (CRD) having 3 replications. Results: Drought stress significantly inhibited the plant growth and its oxidative defense mechanism. Drought stress also affected significantly plant water relations and physiological attributes. Results showed that 35% PEG6000-induced drought stress has affected these parameters with more severity as compared to 15 and 25% stress levels and control plants. Increased quantities of reactive oxygen species (ROS) viz. hydrogen peroxide (Hsub2/subOsub2/sub), malondialdehyde (MDA) and superoxide (Osub2/sub·sup?/sup) were observed due to PEG6000-induced drought stress . Similarly, antioxidative enzymes activities were accelerated due to drought stress with high values for superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR). In contrast, leaf water contents and membrane stability values were recorded with marked decrease, with maximum membrane leakage values for 35% PEG6000 drought stress treatment. Similarly, all drought stress ed plants under 3 stress levels had showed fluctuations for efficiency of dark-adapted PS-II (Fv/Fm), as compared to non-stressed control plants. Conclusion: In crux, drought stress at 35% PEG-6000 considerably influenced the maize seedlings in oxidative defense mechanism, water relations and chlorophyll fluorescence measurements.