Arbuscular Mycorrhizal Fungi Effectively Enhances the Growth of <i>Gleditsia sinensis</i> Lam. Seedlings under Greenhouse Conditions

The Chinese honey locust tree Gleditsia sinensis Lam. (Fabaceae) is a precious ecological and economic tree species that has wide-ranging usage. However, knowledge regarding seedling cultivation (especially the use of arbuscular mycorrhizal fungi (AMF)) is scarce, which limits the developent of Gleditsia plantations. A pot experiment was carried out under greenhouse conditions to estimate the effects of three AMF strains (Funneliformis mosseae 1, Funneliformis mosseae 2, and Diversispora tortuosa) on the growth, photosynthetic rate, and nutrient content of G. sinensis seedlings. Results showed that the growth parameters (seedling height, basal diameter, dry biomass) of the seedlings were significantly increased by each of the three AMF strains, associated with high root colonization rates (greater than 75%). Chlorophyll concentrations and photosynthetic rates were also increased by AMF, and phosphorus (P), and potassium (K) content in the three organs (leaf, stem, and root), and nitrogen (N) content in the leaf and stem of arbuscular mycorrhizal (AM) seedlings were significantly higher than in non-AM seedlings. Mycorrhizal dependency of the AM seedlings was greater than 350%, and significantly correlated with the increased P and K content in all three organs and increased N content in the leaf and stem. Positive effects of F. mosseae on growth and the nutrient content of seedlings were higher than those of D. tortuosa, but no significant different effects on G. sinensis seedlings were observed between the two strains of F. mosseae. Hence, growth of G. sinensis seedlings was effectively enhanced by AMF, with F. mosseae being more suitable for the inoculation of G. sinensis seedlings. These results indicate that arbuscular mycorrhization is beneficial for the growth of young G. sinensis plants. Further research is needed to determine whether the effects can be reproduced in a forest situation.