Effects of drought stress on leaf physiology of Reaumuria soongorica seedlings during the growing season

Taking the desert plant Reaumuria soongorica as the research object, soil moisture content was artificially controlled during the growing season. The control group (CK), mild drought stress (D₁), moderate drought stress (D₂), and severe drought stress (D₃) were set up, respectively. The content of malondialdehyde (MDA), antioxidant enzyme activity and osmotic adjustment substance content were studied in leaves of R. soongorica seedlings under the influence of drought stress. The results showed that compared with the control group, the MDA content of leaves increased significantly under each drought stress treatment, and the increase was the largest under D₃ drought stress. The activities of superoxide dismutase, peroxidase and catalase increased significantly under mild and moderate drought stress. The increase was the largest under D₂ drought stress at the beginning of the growing season. The soluble sugar, free proline and soluble protein contents increased significantly under mild and moderate drought stress. The increase was the largest under D₂ drought stress at the beginning of the growing season, and the changes of various physiological indexes with stress time were August > July > September. These studies showed that the content of MDA in leaves increased with drought stress severity. Antioxidant enzyme activity and the content of osmotic adjustment substances increased under mild and moderate drought stress. The proline content increased under severe stress to remove excess active oxygen from the body and maintain normal functioning of the membrane system. All the indicators were the highest during the period of vigorous growth.