Multi-omics reveals microbial inoculant-mediated mitigation of Dazomet-induced soil disturbances and rhizosphere microbiome recovery in Fritillaria cirrhosa cultivation on the Tibetan plateau.

Abstract

Dazomet fumigation is widely used to control soil-borne pathogens, but its disruption of soil microbial may pose ecological risks, particularly in fragile high-altitude agroecosystems. Microbial inoculants offer an eco-friendly strategy to restore fumigated soils. However, it remains unclear how beneficial microbial inoculants regulate rhizosphere metabolism, microbial assembly, and functional recovery in Dazomet-affected soils used for medicinal plant cultivation. Therefore, this study integrated rhizosphere metabolomics, microbial community profiling, functional prediction, and co-occurrence network analysis to investigate ecological restoration mechanisms of Paecilomyces lilacinus inoculation in Dazomet-fumigated soils cultivated with Fritillaria cirrhosa on the Tibetan Plateau. Results showed that P. lilacinus inoculation significantly alleviated fumigation-associated growth inhibition, increasing F. cirrhosa yield by 150.31%-150.45% and net photosynthetic rate by 66.51%-74.05% compared with fumigated control. Metabolomic analysis showed that microbial inoculation reshaped the rhizosphere metabolic environment, particularly by enhancing soil metabolic pathways related to lipid metabolism, organic acid biosynthesis, biotin metabolism, and ABC transporter-associated processes. These metabolic shifts accompanied enrichment of microbial taxa with functions in xenobiotic degradation, including Methylotenera, Flavobacterium, and Pseudomonas, indirectly suggesting that inoculation may contribute to attenuation of Dazomet derived residues through microbiome mediated processes. In addition, co-occurrence network analysis indicated that P. lilacinus partially restored microbial interaction complexity and strengthened bacterial-fungal associations disrupted by fumigation, exerting a positive effect on rhizosphere community stability. Given the short-term experimental design, relatively controlled conditions, and lack of quantification of Dazomet residues, future studies should validate these findings under long-term field conditions, quantify Dazomet residues and their dissipation dynamics, and elucidate mechanisms underlying microbial inoculation-mediated soil restoration.

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