Effects of continuous cropping on growth and rhizosphere soil microbial community structure of Salvia miltiorrhiza Bge

Continuous cropping has restricted the development of high-quality and high-yield Salvia miltiorrhiza, which has become an urgent problem to be addressed. The evolution of microbial rhizosphere communities is closely related to plant growth, which may be a key factor that is aggravating obstacles to continuous cropping. Therefore, this study explored the effects of continuous cropping on the microbial rhizosphere community of S. miltiorrhiza. Methods: The effects of continuous cropping on the physiological and morphological indices of S. miltiorrhiza were evaluated by pot experiments. The V4 region of the rhizosphere bacterial 16S rDNA gene and ITS1 region of the fungal gene were sequenced by NovaSeq platform high-throughput sequencing technology to explore the effects of continuous cropping on the bacterial and fungal community structure in the rhizosphere of S. miltiorrhiza. Results: After continuous cropping, the biomass of S. miltiorrhiza decreased, the plant wilted and dwarfed, and the effective leaf area, main root length, and diameter significantly decreased. The accumulation of total chlorophyll, carbohydrates, and effective components was significantly reduced, and photosynthesis was reduced. The bacterial and fungal community composition and function in the rhizosphere soil altered significantly. The bacterial diversity in continuous cropping soil decreased, while the fungal community diversity increased, along with the emergence of pathogenic fungi such as Fusarium solani. Conclusion: Continuous cropping led to morphological changes, weak physiological activity, and reduced bioaccumulation of S. miltiorrhiza, and affected the composition of the microbial rhizosphere community. This may be a key factor that aggravates obstacles in continuous cropping.