Objective The aim of this study is to evaluate the effects of soil improvement measure using cultivation substrates on yield and rhizosphere soil fungal community of Pseudostellaria heterophylla. This measure could be helpful to provide the theoretical basis for establishing a sustainable cultivation model.

Methods The effect of cultivation substrates on root rot disease incidence (DI) and yield of P. heterophylla were investigated in different type fields. Furthermore, high-throughput sequencing technology was used to analyze the diversity and structure changes of rhizosphere soil fungal community at different growth stages of P. heterophylla, and the correlations of rhizosphere soil fungal community with the disease incidence and yield.

Results The results showed that the DI was decreased by 4.84%～7.69% and the yield was increased by 39.00%～109.31% in the cultivation substrate treatment soils comparing to the control group. Substrate treatment had the best improvement effect in the mountain soil. At the seedling stage and expanding period, the rhizosphere soil fungal communities in control soil exhibited higher richness than those in the substrate treatment soil, with no significant difference on the fungal community diversity. At the harvest period, however, the fungal community richness of substrate treatment soil increased, but the diversity decreased. The rhizosphere fungal communities in the treatment and control soils were dominated by Ascomycota and Basidiomycota, whose relative abundances were both more than 85%. At the level of genus, Coniochaeta, Candida, Gibellulopsis and Penicillium were the dominant fungi in the treatment soil, while Saitozyma, Didymella, Fusarium and Epicoccum were the dominants in the control soil. At the harvest period, the relative abundance of Fusarium was increased significantly in the control soil and positively correlated with DI of root rot. The yield of P. heterophylla was positively correlated with the abundance of Gibellulopsis and negatively correlated with the abundance of Fusarium.

Conclusion Partial substitution of the original soil of rhizosphere by cultivation substrates was used for soil improvement in continuous cropping fields. The soil improvement measure can reduce the incidence of root rot and increase the yield of P. heterophylla and also improve the structure and diversity of rhizosphere microbial communities by increasing beneficial microorganisms and decreasing the pathogens.