The efficacy of Perilla frutescens rotation and Trichoderma harzianum application in mitigating continuous cropping challenges of Panax notoginseng

Prolonged continuous cropping has the potential to negatively impact soil health, leading to a disruption in the natural succession of Panax notoginseng. Sustainable agricultural practices, such as crop rotation and the application of biological agents, have been shown to enhance soil health and productivity. However, there is a paucity of information on the efficacy of combining these strategies for enhancing soil health. This study pioneered the use of Perilla frutescens rotation in plots with P. notoginseng continuous cropping soil. After crushing the harvested perilla and returning it to the plots, Trichoderma harzianum Rifai strain TH7 was applied. Fallow and continuous P. notoginseng cultivating plots served as controls. One - year - old P. notoginseng seedlings were then transplanted. The mechanism of perilla residues and T. harzianum application in shaping soil microbial communities was also analyzed. Results showed that the perilla aqueous extract with T. harzianum effectively controlled key P. notoginseng pathogens like Fusarium solani, Fusarium oxysporum, and Cylindrocarpon destructans, without inhibiting TH7 growth. The soil quality index (SQI) of fallow soil exhibited a significant increase of 149.16 % compared to that of continuously cropped soil. By contrast, the SQI increased by 161.70 % following perilla rotation, residue return, and subsequent application of T. harzianum. The survival rate of replanted P. notoginseng was about 19 % after fallow or perilla rotation, versus 5.38 % under continuous cropping. However, it rose to 29.23 % with T. harzianum application post- perilla rotation and residue return. These results highlight the effectiveness of integrated agricultural practices in restoring soil health and productivity. This approach of applying T. harzianum post-perilla rotation and incorporating perilla residues significantly improved soil health, enhancing microbial activity and nutrient availability. It also greatly boosted the survival rate of replanted P. notoginseng, offering a new strategy to overcome P. notoginseng continuous cropping obstacles and being highly significant for sustainable agricultural development. The combined effects of crop rotation and biological agent application not only address the immediate challenges of soil degradation but also promote long-term soil fertility and resilience. This integrated strategy represents a promising advancement in sustainable farming practices, particularly for high-value crops like P. notoginseng that are sensitive to soilborne diseases and nutrient imbalances.