The rhizosphere soil properties and bacteria community of poplar are affected by magnetic field under salt condition

Magnetic fields (MFs) are konwn to affect plant growth, but their effects on soil conditions remain obscure. In this study, poplar seedlings (Populus×euramericana 'Neva') were subjected to a MF under saline conditions, and the rhizosphere soil properties and bacterial communities were then examined. Salt stress detrimentally influenced rhizosphere soil nutrients availability and bacterial community structure. However, MF treatments showed several positive effects, such as increasing the ammonium nitrogen (NH4+-N), amorphous iron oxide (Feo) and available phosphorus (AP) contents in the soil. Moreover,. soil urease and acid phosphatase activity increased by 59% and 63%, respectively. Meanwhile, MF treatments significantly improved the contents of extracellular polymeric substances (EPS) in rhizosphere soils and increased the relative abundance of dominant bacteria phyla (e.g., Actinobacteria, Gemmatimonadetes, and Proteobacteria). Furthermore, a co-occurrence network analysis revealed greater modular clustering in the MF treatments, however, the network stability did not improve. In conclusion, MFs increased rhizobacterial community modularity and promoted the production of bacterial EPS, these effects that then enhanced soil nutirent availability and poplar salt tolerance.