Evaluation of Antioxidant Responses of Maize (Zea mays L.) Varieties to Water Stress

摘要

Field and laboratory experiments were performed to evaluate the responses of two varieties of maize - 30P30 and 1144 - against water stress Experiments were performed in two sets of plants. In one set, maize plants were grown in hydroponic condition in petri plates inside the laboratory and water stress was induced by polyethylene glycol on one-week-old seedlings. Relative water content decreased in both the varieties following water stress, but it was greater in var. 1144. Biochemical assays were performed on day 3 and day 7 of stress. Seedlings of second set were sown in plastic pots and drought was induced in two-week-old plants by withholding water in the pots after which sampling was done on day 3 and day 7 of stress. Plants responded to waterstress in both sets by over-expression of antioxidative enzymes such as peroxidase, catalase, ascorbate peroxidase and glutathione reductase. Though superoxide dismutase showed an initial increase in activity at 3 days of water stress, increasing the duration of stress reduced its activity. Water stress induced a marked decline in relative water content and chlorophyll content of the leaf. On the other hand, it induced an increase in phenols proline, ascorbate and carotenoids. Lipid peroxidation and H_2O_2 content showed a marked increase in both sets of plants during stress condition but it was greater in var. 1144. All results taken together indicate that antioxidant responses are greater in var. 30P30 which is more tolerant than var. 1144.