Effects of monocropping soil on plant growth and rhizosphere microbial community structure of <i>Salvia miltiorrhiza</i> Bge

<i>Salvia miltiorrhiza</i> (Danshen) is a commonly utilized remedy for various blood stasis syndromes, cardiovascular, and cerebrovascular diseases. The practice of continuous cropping presents a notable challenge to the production of high-quality <i>S. miltiorrhiza</i> due to the lack of rotation or soil remediation. Despite this, the precise mechanism, particularly the impact of alterations in the rhizosphere microbial community structure on the development of obstacles related to continuous cropping, remains obscure. The constitution of the rhizosphere microbial community plays a pivotal role in plant growth and has the potential to exacerbate issues associated with continuous cropping. This study aimed to comprehensively compare the impact of continuous <i>vs</i>. non-continuous cropping soils on the growth, physiological and biochemical characteristics, accumulation of active ingredients, and rhizosphere microbial community structure of <i>S. miltiorrhiza</i> seedlings to elucidate the microbial ecological mechanism behind continuous cropping challenges. A pot experiment was executed to assess the effects of continuous cropping on the morphological and physiological parameters of <i>S. miltiorrhiza</i>. High-throughput sequencing technology utilizing the NovaSeq platform was employed to sequence and analyze the V4 region of bacterial 16S rDNA and the ITS1 region of fungi in the rhizosphere. The findings revealed that continuous cropping soil led to a reduction in <i>S. miltiorrhiza</i> biomass, manifesting as wilting and stunted growth, diminished effective leaf area, main root length and diameter, reduced levels of total chlorophyll, carbohydrates, and active ingredients, as well as compromised photosynthesis. In the rhizosphere soil, both the composition and function of the fungal community have undergone significant changes, and the fungal diversity has shown a clear increasing trend; in contrast, the change in bacterial diversity is very slight. In conclusion, continuous cropping soil substantially hinders the growth of <i>S. miltiorrhiza</i>, diminishes its physiological functions, and disrupts the structure of the rhizosphere microbial community. These changes likely contribute significantly to the exacerbation of challenges associated with continuous cropping. This investigation furnishes a theoretical foundation for comprehending the microecological mechanism underpinning continuous cropping challenges in <i>S. miltiorrhiza</i> and devising strategies for soil amelioration.