Revised:
The Qinghai-Tibet Plateau, an alpine and high-altitude area, is frequently subjected to freeze-thaw stress. Due to global climate change, soil drought and salinization in this area have become increasingly severe, along with low temperatures, which are the main limiting factors for crop growth. This study investigated the physiological responses of blue barley seedlings to salinization (S), drought (D), and freeze-thaw (F) stresses. The changes in relative water content (RWC), soluble protein, malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD) were analyzed in seedling leaves under eight treatment groups: CK, S, D, DS, F, FD, FS, and FDS.
Results showed that a single stressor such as NaCl or drought or freeze-thaw caused a decrease in RWC and an increase in soluble protein and MDA content as well as SOD and POD activity in leaves. During the freeze-thaw cycle, the soluble protein, MDA content, SOD, and POD activity initially increased then gradually decreased while RWC gradually decreased with temperature changes. This research indicated that synergistic effects occurred among droughts, NaCl exposure and freeze-thaw on plants; compound stress caused more serious effects on the plant compared to single stressors.




