Crop rotation alleviates continuous cropping obstacles in Chrysanthemum morifolium production by regulating rhizosphere soil microbial communities and metabolites.

Background: Crop rotation is a well-established agricultural practice that enhances biodiversity in medicinal crop fields, thereby improving agroecosystem sustainability and efficiency. However, the impact of crop rotation involving Chrysanthemum morifolium on soil microbiomes and their correlation with key soil physicochemical factors remains insufficiently understood. This study investigates the effects of a rotation system (Prunella vulgaris-C. morifolium) on C. morifolium productivity and soil quality.

Methods: In this study, we investigated two distinct planting models: the P. vulgaris-C. morifolium rotation system and the C. morifolium monoculture system. For each system, we comprehensively examined the agronomic traits, yield, and quality of C. morifolium. Additionally, we analyzed the soil physicochemical properties, soil enzyme activities, rhizospheric microbiome community structures, and rhizospheric metabolite levels to elucidate the underlying mechanisms and differences between the two planting models.

Results: Our findings demonstrate that the rotation model significantly improves C. morifolium yield and quality compared to monoculture. The underlying mechanisms were further analyzed, revealing substantial enhancements in soil nutrient levels, including organic matter, ammonium nitrogen, available phosphorus, potassium, and iron. Similarly, the activity of key soil enzymes-acid phosphatase, sucrase, and β-glucosidase-was significantly increased in the rotation system. Additionally, the incidence of wilt disease was markedly reduced, likely due to a decline in Fusarium abundance. Redundancy analysis identified that soil nutrient enrichment and enzymatic activity enhancement in the rotation system were primarily influenced by Actinobacteria, Cyanobacteria, unclassified bacteria, and Basidiomycota. Furthermore, the presence of acidic metabolites in the rhizosphere notably affected microbial community composition.

Conclusion: Crop rotation effectively modifies rhizospheric microbial communities and metabolite composition, increases soil fertility, enhances the abundance of beneficial microorganisms, and suppresses Fusarium, the pathogen responsible for wilt disease. These findings provide valuable insights into overcoming continuous cropping challenges and offer practical strategies for improving the yield and sustainability of medicinal plant cultivation.