Rhizobacterial communities, enzyme activity, and soil properties affect rice seedling's nitrogen use

Abstract Microorganisms are crucial in mediating N cycles in soil and produce impact on the health and nutrition of the host plant. The seedling stage is one of the most critical periods of crop growth and development. However, the information regarding the underlying interactions between soil microbial community, soil nutrient, enzyme activities, and microbial biomass, and whether they associate with nitrogen use efficiency (NUE) of N at the rice (Oryza sativa L.) seedling stage are still limited. We applied 16S ribosomal RNA gene profiling to characterize root bacterial microbiota of rice varieties with different levels of NUE at the seedling stage. We find that high nitrogen use efficiency varieties (HNUEs) and low nitrogen use efficiency varieties (LNUEs) recruit distinct root microbiota. Notably, HNUEs‐enriched bacterial taxa are more diverse, and contain more operational taxonomic units (OTUs) with N metabolism functions, than LNUEs‐enriched taxa. We provide evidence that the content of available N and the microbial biomass of HNUEs' rhizospheric soil are higher than those of LNUEs. Through redundancy analysis (RDA), we found that Deltaproteobacteria, Acidobacteria, Bacteroidia, and Saccharimonadia with the potential function of the beneficial microorganism to seedling N use and growth. The links between rice seedling and soil microbiota membership combine with other essential factors established in this study could contribute to improving N use at the crop seedling stage to promote the resistance and survival rate after transplanting.