Organic fertilizer substitution improves soil quality and medicinal plant performance to realize sustainable production of Epimedium pubescens Maxim.

Abstract

Epimedium pubescens Maxim., a valuable medicinal plant rich in bioactive flavonoid glycosides, faces constrained sustainability in production due to soil degradation and rhizosphere microecological imbalance induced by excessive chemical fertilization, which limits the enhancement of its medicinal plant performance and hinders sustainable production. Organic fertilizer substitution, proposed as a sustainable solution, was conducted in a two-year field experiment assessing its effects on plant productivity, soil properties, and rhizosphere microbiome in intensive E. pubescens systems. A multidimensional assessment was performed using the SQI-MDS and SI. Results demonstrated that organic substitution treatments significantly outperformed conventional chemical fertilization (OF0): the yield of E. pubescens increased by 32.56%-59.70%, and the total flavonoid glycosides content increased by 8.12%-18.79%, with the OF75 treatment achieving optimal comprehensive benefits. The SQI-MDS index showed progressive improvement in the order: CK < OF0 < OF25 < OF50 < OF75 < OF100. For instance, the SQI-MDS values under organic treatments (e.g., OF75 and OF100) increased by 32.1% and 41.2% compared with OF0, respectively, indicating a substantial upgrade in soil quality. The rhizosphere microbiome was shifted favorably, with beneficial phyla (e.g., Firmicutes, Mortierellomycota) and functional genera (e.g., Trichoderma, Paraglomus) enriched, while pathogenic fungi (e.g., Fusarium, Dactylonectria) were decreased, and bacterial diversity was restored. Sustainability evaluation confirmed high-substitution treatments (OF50, OF75, OF100) met the sustainability standard (SI ≥ 1.30), outperforming chemical treatment and low-substitution treatment. PLS-PM and SEM analysis confirmed that soil quality improvement mediated by organic fertilization was the core driver of enhanced plant benefits and system sustainability. These findings demonstrate that organic fertilization enhances system sustainability in E. pubescens production by improving soil quality and reshaping the rhizosphere microbiome, offering a concrete strategy for sustainable cultivation of medicinal plants.