Effect of continuous cropping on bacterial and fungal communities in Glehnia littoralis soil.

Rhizosphere soil microorganisms are critical in the plant's growth and soil health. Continuous cropping had significant effects on rhizosphere soil microbial community. This study used Glehnia littoralis of 1-year (primary soil, FS), 2-year (continuous cropping soil, CS), and 0-year (Fallow, control soil, CK) soils as test materials, and used high-throughput sequencing technology to study the effects of continuous cropping on the composition, structure, and diversity of microbial communities in the rhizosphere soil of Glehnia littoralis. The results indicate that Proteobacteria, Acidobacteria, and Actinobacteria were the dominant bacteria, the relative abundance of Actinobacteria and Acidobacteria in the bacterial community decreased with the increase of the planting years, which may significantly reduce the microbial diversity and cause the negative effects of continuous cropping of G. littoralis; Ascomycota, Basidiomycota, and Zygomycota were dominant phylum fungi. The α-diversity of fungi in CS was significantly lower than that in other treatments. This study also focuses on soil chemistry and enzymatic activity. pH value, urease activity, and total nitrogen content were higher in the continuous cropping soil. Redundancy analysis showed that soil nutrients, pH value, and urease activity had significant effects on soil fungal and bacterial communities. Significant correlations were detected between soil total nitrogen and urease, and between soil total phosphorus and total potassium. In conclusion, continuous cropping increases soil pH, total nitrogen, and urease activity; decreases fungal diversity; and decreases relative abundance of bacterial dominant bacteria. The interaction and mutual influence of these factors may be the main cause of continuous cropping obstacle of G. littoralis.