Physiological Effects of Freeze-Thaw, Cadmium and Ambrosin Combined Stress on Secale cereale L. Seedlings

Abstract

Abstract Rye is a kind of wintering forage grass, distributed in China in the Qinghai-Tibet Plateau, northeast China and other alpine or arid areas. Additionally, ragweed, an invasive plant originated from the North America, is widely distributed in the northeast region of China, releasing ambrosin-based allelopathic substances to the environment and inflicting a wide impact on crops. In this experiment, the physiological response of Winter 70 rye under the compound stress of freeze-thaw, Cd and ragweed is studied, and the soluble sugar, soluble protein, CAT, MDA, SOD content and photosynthesis changes of rye seedlings under stress were analyzed. The results showed that under the stress of Cd and ambrosin, the content of MDA, soluble protein and soluble sugar, and CAT content increased, and the SOD content decreased under Cd stress, and the SOD content increased under ambrosin stress. Under freeze-thaw stress, MDA content, soluble protein and soluble sugar content, CAT content increased first and then decreased, and SOD content decreased. In the freeze-thaw cycle, low temperatures adversely affect ryegrass seedlings. The reaction of SOD and MDA during cooling process is evident. The net photosynthetic rate of freeze-thawed and ryegrass seedlings is significantly affected by stress, which is manifested by the reduction of net photosynthetic rate forced by a single stress, and the reduction of compound stress is greater than that of a single stress. This study provides a new understanding of the physiological response of rye to Cd and Ambrosin stress under freeze-thawing conditions, and provided clues for the management and evaluation of combined stress.