Simulated water stress on seed germination and physiological regulation of perennial ryegrass

This study aimed to determine the characteristics of water metabolism during seed germination of perennial ryegrass (Lolium perenne) and the effect of water stress on physiological regulation during seed germination. Water absorption by seeds of perennial ryegrass was continuously observed for 48 h, and the seeds were treated to stress conditions of drought and waterlogging, to study the effects of water stress on germination, starch metabolism, anaerobic respiration enzyme activity, and antioxidant enzyme activity in ryegrass seeds. The results showed that ryegrass seeds are in the period of rapid water absorption from 0 to 24 h and tend to saturation after 36 h. Water absorption and water absorption rate of seeds were significantly affected by drought stress (P < 0.05), and gradually decreased with the increase in drought degree. Compared with the control, treatments of 15% polyethylene glycol and waterlogging stress significantly reduced the germination energy, germination rate, germination index, and α-amylase activity of ryegrass seeds (P < 0.05). Under waterlogging stress, the alcohol dehydrogenase activity of ryegrass seeds was significantly increased (P < 0.05). Compared with the control, under drought and waterlogging stress, the activities of superoxide dismutase, peroxidase, and catalase in ryegrass seeds were significantly increased (P < 0.05). The results of this study provide a theoretical reference for water management of the ryegrass seed germination process.