Effects of Arbuscular Mycorrhizal Fungi on Growth, Photosynthesis, and Nutrient Uptake of Zelkova serrata (Thunb.) Makino Seedlings under Salt Stress

Salinity is the primary restriction factor for vegetation conservation and the rehabilitation of coastal areas in Eastern China. Arbuscular mycorrhizal fungi (AMF) have been proved to have the ability to alleviate salt stress in plants. However, the role of AMF in relieving salt stress among indigenous trees species is less well known, limiting the application of AMF in the afforestation of local area. In this study, a salt-stress pot experiment was conducted to evaluate the effects of AMF on Zelkova serrata (Thunb.) Makino, a tree species with significant potential for afforestation of coastal area. The Z. serrata seedlings inoculated with three AMF strains (Funneliformis mosseae 1, Funneliformis mosseae 2, and Diversispora tortuosa) were subjected to two salt treatments (0 and 100 mM NaCl) under greenhouse conditions. The results showed that the three AMF strains had positive effects, to a certain extent, on plant growth and photosynthesis under normal condition. However, only F. mosseae 1 and F. mosseae 2 alleviated the inhibition of growth, photosynthesis, and nutrient uptake of Z. serrata seedlings under salt stress. The two AMF strains mitigated salt-induced adverse effects on seedlings mainly by increasing the leaf photosynthetic ability and biomass accumulation by reducing Na+ content, increasing P, K+, and Mg2+ content, as well as by enhancing photosynthetic pigments content and the stomatal conductance of leaves. These results indicated that AMF inoculation is a promising strategy for the afforestation of coastal areas in Eastern China.