Effect of earthworms and arbuscular mycorrhizal fungi on the microbial community and maize growth under salt stress

The aim of this study was to investigate the independent and interactive effectiveness of epigeic earthworms and arbuscular mycorrhizal (AM) fungi as soil conditioners in modifying the properties of salt-affected soil and increasing maize productivity. Treatments included maize plants inoculated vs. not inoculated with AM fungi and treated with or without earthworms. The mycorrhizal colonization, soil pH, electric conductivity (EC), nutrient availabilities and uptakes, catalase, soil microbial biomass C, and Shannon-Wiener index (H) for microbial communities from T-RFLP profiles were measured at harvest. The results showed that erthworms and AM fungi interactively decreased soil pH and EC, and increased the N, P and K content of maize shoot and root and their biomass. Earthworms and AM fungi interactively increased soil organic C, catalase activity and microbial biomass C in the saline alkali soil. Earthworms significantly decreased bacterial diversity, while earthworms and AM fungi interaction significantly increased fungal diversity. Pontibacter and Methylobacteriu were dominant bacteria, and Stachybotrys and Trichoderma were dominant fungi for all treatments. Earthworm addition significantly improved the abundance of Pontibacter and decreased the abundance of Methylobacteriu, which might result in higher soil P availablity and N absorption, respectively. Earthworms, AM fungi and their interaction increased the abundance of Trichoderma but decreased the abundance of Stachybotrys. Maize biomass and nutrient uptakes correlated significantly with the abundance of Trichoderma and Stachybotrys. In conclusion, earthworms, mycorrhiza and their interaction may have a potential role in elevating the chemical and biological properties to alleviate salinity and improve crop productivity in salt-affected soils.