Root Rot Disease Occurrence, Yield and Rhizosphere Fungal Community of Pseudostellaria heterophylla Grown on Soil Modified with Culture Substrate

Objective Effects of adding culture substrates in soil on tuberous root rot disease occurrence, yield and rhizosphere fungal community of Pseudostellaria heterophylla were studied, which would provide the theoretical basis for establishing a sustainable cultivation model.

Methods Root rot disease incidence (DI) and yield of P. heterophylla, which were cultivated in different type of fields using culture substrates to modify the ground soil, were monitored. Diversity and structure of the fungal community in the rhizosphere at different plant growth stages were analyzed by high-throughput sequencing. The correlations of rhizosphere fungal community with the DI and yield were conducted.

Results The DI was reduced by 4.84%–7.75% and yield increased by 39.00%–109.31% via the culture substrate addition in soil comparing to the control group. The greatest improvement effects were observed in the soil on hilly lands. At the seedling and expanding stages, the rhizosphere fungal community under treatments was lowered in richness but not significantly changed in diversity. At the harvest stage, the treatments increased the richness and reduced the diversity. In all rhizosphere soils, Ascomycota and Basidiomycota were the dominant fungi. At the genus level, Coniochaeta, Candida, Gibellulopsis, and Penicillium were predominant in the treatment soils, while Saitozyma, Didymella, Fusarium, and Epicoccum were dominant at the control sites. At the harvest stage, the relative abundance of Fusarium was increased significantly in the control soils and positively correlated with DI of root rot. The yield of P. heterophylla was positively correlated with the abundance of Gibellulopsis, but negatively with that of Fusarium.

Conclusion Soil improvement in different types of continuous cropping fields of P. heterophylla could be realized by partially replacing rhizosphere soil with culture substrates, which could reduce the root rot DI, increase the tuberous root yield of P. heterophylla, and also improve the structure and diversity of rhizosphere microbial communities by promoting beneficial microorganisms and inhibiting the pathogens.