Effects of short‐term nitrogen addition on rhizosphere and bulk soil bacterial community structure of three halophytes in the Yellow River Delta

Abstract

AbstractThe total amount and rate of atmospheric nitrogen (N) deposition are constantly increasing, which substantially influences the soil microbial community structure and function. However, it is still unclear whether the responses of different plant rhizosphere soil bacterial community to short‐term N addition was consistent. Based on 16s rRNA sequencing, we investigated the responses of rhizosphere and bulk soil bacterial community of halophytes (salt‐absorbing, salt‐rejecting, and salt‐secreting plant) to short‐term N addition in the Yellow River Delta. The bacterial community α‐diversity of Suaeda salsa (salt‐absorbing plant) was significantly higher in rhizosphere soil than in bulk soil, while no significant difference between Phragmites communis (salt‐rejecting plant) rhizosphere and bulk soil bacterial community α‐diversity was found. The differences were mainly ascribed to the higher N uptake capacity of P. communis, which resulted in no difference in N content between rhizosphere and bulk soil. The short‐term N addition significantly increased the α‐diversity of bacterial community in the rhizosphere soil of Aeluropus sinensis (salt‐secreting plant), but there was no effect on the α‐diversity of bacterial community in the rhizosphere soil of P. communis. Nitrogen addition enhances the salt uptake capacity of A. sinensis and alleviates the salt stress of bacterial growth. The relative abundance of Bacteroidetes for S. salsa and A. sinensis was significantly higher in rhizosphere soil than in bulk soil, and the relative abundance of Actinobacteria for P. communis and S. salsa was higher and lower in rhizosphere soil than in bulk soil, respectively. Salt‐absorbing of S. salsa leads to elevated rhizosphere soil salinity. Higher salinity and abundant carbon promote the Bacteroidetes and inhibit the Actinobacteria. Short‐term N addition caused an increase in the relative abundance of Gemmatimonadetes in halophyte rhizosphere soil and a decrease in the relative abundance of Firmicutes in S. salsa and A. sinensis bulk soil, which may be due to the different response of C:N of root secretions to N addition in halophytes. The relative abundance of rhizosphere soil denitrifying bacteria was higher in S. salsa and A. sinensis than in P. communis, while the reverse was observed for N‐fixing bacteria. The relative abundance of denitrifying bacteria decreased in P. communis and increased in S. salsa and A. sinensis. The low N soil environment of P. communis promotes the activity of N‐fixing bacteria, and the abundant N content of S. salsa and A. sinensis soil promotes the denitrification process. The research clarified that the response of soil bacterial community to short‐term N addition Treatment differed due to the influence of plant species and that N additions had smaller effects on the bacterial community than plant species.