Mechanistic insights into natural fallow-mediated mitigation of Panax notoginseng replant obstacle

Abstract

Continuous cropping obstacles in Panax notoginseng cultivation, marked by allelochemical accumulation and soil microecological dysbiosis, were investigated through dynamic changes in soil structure, physicochemical properties, rhizosphere metabolites, and microbial communities during fallow periods. Metabolomic and metagenomic analyses of continuously cropped versus fallow soils revealed degraded soil structure with finer particles and reduced aeration post-cultivation. Severe seed germination inhibition and complete seedling mortality within months occurred in continuous cropping soil, whereas fallow practices enhanced both germination rates and seedling survival. Metabolomic profiling identified key allelochemicals enriched in continuously cropped soils, primarily terpenoids, tannins, and specific phenolic acids. These compounds correlated with enrichment of adverse genera (Pseudomonas, Sphingomonas) and suppression of beneficial taxa (Bradyrhizobium). Fallow partially restored carbohydrate and nucleotide metabolism pathways and recruited growth-promoting metabolites. Correlation analyses revealed critical metabolite-microbe crosstalk: allelochemicals promoted pathogens while suppressing symbionts essential. This integrative multi-omics approach deciphered key rhizosphere ecological interactions, demonstrating that metabolite-driven microbial shifts constitute primary drivers of continuous cropping obstacles.

Graphical abstract

Keywords

Panax notoginseng / continuous cropping obstacle / rhizosphere metabolites / rhizospheric microorganism

Highlight

	● Allelochemicals of P. notoginseng are mainly terpenoids, tannins, and phenolic acids.
	● Allelochemicals drives structural reorganization of microbial communities.
	● Detrimental pathogenic microorganisms involve Pseudomonas and Sphingomonas.

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