Seedlings of rye (Secale cereale) respond to freeze-thaw, alkaline salt, and Solanum rostratum Dunal extract combined stress by increasing soluble protein and antioxidant enzyme activity

The grassland in north-east China has an important ecological service function. However, freeze-thaw, alkaline salt, and Solanum rostratum Dunal often have adverse effects on the stability of grassland ecosystem in this region. In this study, the effects of combined stress of freeze-thaw, alkaline salt, and S. rostratum extract on rye (Secale cereale ) were discussed. It was found that the combined stress of alkaline salt and S. rostratum extract (AR) inhibited the seed germination and seedling growth of rye. Compared with AR in the non-freeze-thaw group, the contents of soluble protein (SP), malondialdehyde (MDA) and hydrogen peroxide (H2 O2 ) of rye seedlings were significantly increased under the combined stress of freeze-thaw, alkaline salt, and S. rostratum extract (FAR), and the activities of superoxide dismutase (SOD) and peroxidase (POD) were significantly increased. Photosynthetic indices (Tr, Pn, gs , Ci) were significantly decreased. The results indicated that freeze-thaw could aggravate the adverse effects of AR treatment on rye seedlings. Therefore, in the period of frequent freeze-thaw, it is important to carry out timely targeted control measures for S. rostratum to reduce the adverse effects of combined stress on grassland ecosystem, which is conducive to the ecological security and stability maintenance of grassland ecosystem in north-east China.