Mechanism analysis of melatonin pretreatment to improve drought tolerance of perennial ryegrass (Lolium perenne)

In order to further analyze the mechanism of melatonin (MT) pretreatment on drought resistance in perennial ryegrass (Lolium perenne), the effects of 25 μmol·L^–1 MT pretreatment on the antioxidant enzyme activities and the accumulation of metabolites were analyzed. The results showed that MT pretreatment significantly delayed decreases in turf quality, photochemical efficiency, and relative water content; it also increased the rate of relative conductivity and the malondialdehyde content in perennial ryegrass. MT pretreatment maintained the stability of cell membrane systems by increasing the activities of superoxide dismutase, catalase, and peroxidase under drought stress. MT pretreatment may improve the osmotic adjustment ability and oxidative resistance of perennial ryegrass by improving the accumulation of related metabolites, such as isoleucine, proline, ornithine, erythrulose, and glucosamine, which lead to an increase in drought resistance for perennial ryegrass.