Effects of arbuscular mycorrhizal fungi on the growth and metabolism of perennial ryegrass (Lolium perenne) under salt stress

Abstract

Perennial ryegrass is considered an excellent cold-season turfgrass, and salinity is an important environmental factor that affects its growth. Many studies have shown that arbuscular mycorrhizal (AM) fungi can alleviate stress responses in plants, but there have been few reports on the promotion of turfgrass growth in saline-alkali land by AM fungi. We designed an experiment to investigate the effects of different saline conditions (0%, 0.05%, 0.1% salt, w/w) on the growth and physiological metabolism of perennial ryegrass. The results showed that under 0.05% salt stress, AM fungi increased the plant height by 25.9%, the aboveground and underground dry weight by 37.1% and 55.6%, respectively; and the content of chlorophyll a in the plants by 31.0%. Inoculation with AM fungi increased the net photosynthetic rate (A), transpiration rate (E), intercellular CO2 concentration (Ci), and stomatal conductance (Gs) of perennial ryegrass, and the increase in their levels negatively correlated with increasing salt concentrations. Under 0.1% salt stress, the A, Ci, Gs, and E of perennial ryegrass inoculated with AM fungi increased by 24.6%, 23.2%, 139.1%, and 40.7%, respectively. However, inoculation with AM fungi reduced Fv/Fm and had no significant impacts on the SOD activity, MDA, proline (Pro) content, soluble sugar content, and soluble protein content of perennial ryegrass. In conclusion, AM fungi can promote the growth of perennial ryegrass under salt stress, enhance its photosynthetic capacity, and improve the ability of perennial ryegrass to resist salt stress.