Density-Driven Root Exudate Remodeling Promotes Pathogen Enrichment and Exacerbates Negative Plant–Soil Feedback in Panax notoginseng Monoculture Systems
J Zhang·Min Yang·Chaocang Chen·Chen Ye·Shijun Zhong·Linmei Deng·Lifen Luo·Haijiao Liu·Shusheng Zhu·Mingyue Wang
Negative plant–soil feedback (NPSF) drives yield decline in monocropping systems, yet how intraspecific competition modulates NPSF across planting densities remains unclear. We conducted a two-stage plant–soil feedback experiment using five crops (Triticum aestivum L., Zea mays L., Solanum lycopersicum L., Cucumis sativus L., and Panax notoginseng (Burkill) F.H. Chen) with contrasting NPSF intensities under four planting densities (30 × 30 to 8 × 8 cm). Crops with stronger NPSF (P. notoginseng)