Effects of long-term water stress on protective enzyme activities and lipid peroxidation in summer maize roots and leaves

Using rain proof installations, a systematic study was conducted to determine the effects of water stress on protective enzyme activities and lipid peroxidation. The results showed that, under water stress, activities of superoxide dismutase(SOD), catalase(CAT), and peoxidase(POD) in leaves and roots increased sharply at prophase and metaphase such as male tetrad stage, while declined at the evening growth stages such as milky stage. Different responses of maize to water stress under field conditions were found at different growing stages. At the stage of male tetrad and the pre-tasselling, the mechanism of response to drought is active, while at the stage of filling and milking is forbearing negatively. The protective enzyme activities in roots are lower than that in leaves, but the sensitive degree of these enzymes to water stress is different. SOD activities are less sensitive under drought stress compared with other protective enzymes. The content of malondialdehyde (MDA) is increased under stronger water stress, and the content of MDA in roots is lower than that in leaves. The soluble protein in roots and leaves is decreased under water stress. The protective enzyme activities and lipid peroxidation in roots are positively related to that in leaf, showing significant difference for most of correlation coefficients.