The synergy effect of arbuscular mycorrhizal fungi symbiosis and exogenous calcium on bacterial community composition and growth performance of peanut ( Arachis hypogaea L.) in saline alkali soil

Peanut ( Arachis hypogaea. L) is an important oil seed crop. Both arbuscular mycorrhizal fungi (AMF) symbiosis and calcium (Ca 2+ ) application can ameliorate the impact of saline soil on peanut production, and the rhizosphere bacterial communities are also closely correlated with peanut salt tolerance; however, whether AMF and Ca 2+ can withstand high-salinity through or partially through modulating rhizosphere bacterial communities is unclear. Here, we used the rhizosphere bacterial DNA from saline alkali soil treated with AMF and Ca 2+ alone or together to perform high-throughput sequencing of 16S rRNA genes. Taxonomic analysis revealed that AMF and Ca 2+ treatment increased the abundance of Proteobacteria and Firmicutes at the phylum level. The nitrogen-fixing bacterium Sphingomonas was the dominant genus in these soils at the genus level, and the soil invertase and urease activities were also increased after AMF and Ca 2+ treatment, implying that AMF and Ca 2+ effectively improved the living environment of plants under salt stress. Moreover, AMF combined with Ca 2+ was better than AMF or Ca 2+ alone at altering the bacterial structure and improving peanut growth in saline alkali soil. Together, AMF and Ca 2+ applications are conducive to peanut salt adaption by regulating the bacterial community in saline alkali soil.