Sugarcane–peanut intercropping improves rhizosphere fungal communities and metabolites following long-term continuous peanut monoculture

Abstract

Sugarcane-peanut intercropping improves land use efficiency and crop productivity, yet the rhizosphere mechanisms through which this system alleviates continuous peanut monoculture soil sickness and regulates rhizosphere fungal-metabolite balance remain poorly understood. This study integrated amplicon sequencing and untargeted metabolomics to investigate fungal community dynamics and metabolite profiles in the peanut rhizosphere under monoculture and three intercropping row spacings (2.0 m, 2.4 m, and 3.0 m). Intercropping produced coordinated, row-spacing-dependent shifts in peanut rhizosphere fungal taxa, metabolite profiles, land-use efficiency, and kernel quality. Although overall fungal and metabolite beta-diversity differences were not significant, SP2.4 showed the largest set of differentially abundant fungal taxa, while SP2.0 achieved the highest land equivalent ratio. Across spacings, intercropping depleted several Aspergillus and Fusarium taxa and enriched candidate beneficial fungi, including Trichoderma species. Untargeted metabolomics further revealed spacing-specific enrichment of phenolic, stilbenoid, and terpenoid compounds with reported roles in plant defense or fungal inhibition. A feature putatively annotated as aflatoxin B 1 by untargeted LC–MS/MS library matching was less abundant under intercropping. Together, the results indicate that sugarcane–peanut intercropping can improve the rhizosphere microecological state of long-term monocropped peanut fields through coordinated fungal and metabolic reorganization. A row-spacing window of 2.0–2.4 m provided the most favorable balance between system productivity and belowground microecological improvement.