Sustainable management of soil-borne disease: integrating fumigation with Andrographis paniculata residues to rebuild rhizosphere function.

Continuous pepper cropping induces soil-borne diseases and disrupts rhizosphere microecological balance. This study employed untargeted metabolomics and metagenomics to investigate treatment effects on rhizosphere metabolic reprogramming and microbe-metabolite interactions. Aqueous and ethanolic extracts of Andrographis paniculata residues (TCMR) were rich in flavonoids, terpenoids, and phenolic acids, exhibiting significant inhibition against soil-borne pathogens (Fusarium oxysporum, Fusarium solani, and others; >70% inhibition at high doses). While single fumigation (W1, M1) transiently suppressed pathogens, it disrupted rhizosphere metabolic homeostasis. In contrast, combined fumigation-TCMR treatments (WC, MC) enhanced plant stress resistance, stabilized membrane integrity, and reshaped microbial communities by modulating amino acid, lipid, and phenylpropanoid biosynthesis pathways. Microbe-metabolite network analysis revealed that coupling carbon-nitrogen cycling with redox homeostasis drives soil microecological optimization. This integrated strategy provides a sustainable solution for continuous cropping obstacles through synergistic metabolic reprogramming and microbiome reconstruction.