Effect of arbuscular mycorrhiza and a grass endophyte on the drought tolerance of perennial ryegrass

We established a pot experiment in a greenhouse to study the effects of arbuscular mycorrhiza(AM) fungus and a grass endophyte on perennial ryegrass drought tolerance, aiming to identify two kinds of symbioticmic roorganisms to improve plant drought stress tolerance. The AM treatments involved inoculation with or without arbuscular mycorrhizal fungus.Seeds of perennial ryegrass infected with a grass endophyte (E+) and without grass endophyte (E-) were used to establish plants with and without a grass endophyte, respectively. After 38 days of growth, ryegrass grown in the above microorganism treatments were exposed to four soil water treatments of 15%, 30%, 45%, and 60% of the maximum soil water holding capacity. The mycorrhizalfungus and grass endophyte mostly showed positive effectson plant growth and nutrition uptake in 45% and 60% soil water. The two types of symbiotic fungi not onlypromoted the growth of perennial ryegrass and enhanced shoot and root biomass but also promoted plant nitrogen and phosphorus uptake, enhanced peroxidase activity, and reduced malonaldehyde concentrations.Therefore, the two symbionts enhanced plant drought tolerance and reduced (P<0.05) the damage to perennial ryegrass under semi drought stress.