Effects of pepper–mung bean intercropping on pepper productivity, nutrient accumulation, and rhizosphere microbial communities under continuous cropping

Continuous monocropping can impair sustainable pepper ( Capsicum annuum L.) production by disrupting soil nutrient availability, microbial communities, and biological functioning. Legume-based intercropping offers a potential strategy to alleviate these constraints, but its effects in continuously cropped pepper systems remain poorly understood. Here, a field experiment was conducted in a long-term continuously cropped pepper field to evaluate the effects of mung bean intercropping on pepper growth and yield, nutrient accumulation, rhizosphere soil properties, and microbial communities. Compared with pepper monocropping (MP), pepper–mung bean intercropping (IP) significantly increased average fruit weight and pepper yield, but did not affect plant height, stem diameter, or fruit number per plant. IP altered the accumulation and distribution of N, P, and K among pepper organs, particularly in reproductive tissues. In the rhizosphere, IP increased available N, P, and K and urease, dehydrogenase, and catalase activities, while total N, P, and K remained unchanged. Amplicon sequencing revealed significant differences in bacterial and fungal community composition between MP and IP. At the fungal genus level, Bisifusarium and Neocosmospora were enriched under MP, whereas Conocybe was enriched under IP. IP also increased the relative abundances of several bacterial taxa, particularly Vicinamibacterales , Vicinamibacteraceae , KD4-96 , and Rokubacteriales . Several IP-enriched taxa were positively correlated with rhizosphere nutrient availability, soil enzyme activities, and pepper yield-related traits. Overall, mung bean intercropping was associated with improved rhizosphere nutrient availability and enzyme activities, together with substantial restructuring of bacterial and fungal communities, and may therefore contribute to improved pepper productivity under continuous cropping.