Control of Panax notoginseng root rot through the combined application of biogas slurry and Bacillus and its mechanistic insights

Abstract

Background and aims

Replant failure in Panax notoginseng (Sanqi) is often caused by root rot disease, which is exacerbated by continuous cropping. This study aimed to assess the effectiveness and mechanisms of biogas slurry (BS) combined with Bacillus velezensis strain B19 in controlling root rot and improving soil health in Sanqi cultivation.

Methods

A pot experiment was conducted comparing untreated soil, soil treated with BS alone, and soil treated with BS combined with B. velezensis B19. Soil properties, enzyme activities, and microbial community structure were analyzed to evaluate the treatments'effects and mechanisms on disease suppression.

Results

The application of BS, either alone or with Bacillus, significantly improved soil properties by enhancing available phosphorus, organic matter, and enzyme activities (e.g., β-glucosidase and fluorescein diacetate hydrolase). BS alone reduced root rot incidence to 62.5% compared to 82.5% in untreated soil. Notably, the combined BS and Bacillus treatment further reduced root rot incidence to 28.1% (P < 0.05), significantly outperforming BS alone. Disease suppression mechanisms included Bacillus enrichment in the rhizosphere, increased bacterial diversity, altered microbial community structure, and the stimulation of beneficial taxa such as Lysobacter and Trichoderma, which inhibited pathogens like Fusarium, Plectosphaerella, and Ilyonectria.

Conclusion

The combination of BS and Bacillus offers a promising approach to reduce root rot in Sanqi by improving soil health, enhancing beneficial microbial communities, and suppressing pathogens. This approach shows promise as a sustainable strategy for managing root rot in Sanqi cultivation.