Enrichment of phytopathogen dominated by Volutella in the rhizosphere may be an important cause of continuous cropping obstacles in sweetpotato

Obstacles related to the continuous cropping of sweetpotato ( Ipomoea batatas (L.) Lam.) restrict its intensive production. However, the effects of continuous cropping on soil properties and/or the rhizosphere microbial community are largely unclear. In this study, we analysed changes in rhizosphere soil chemical properties and microbial communities of sweetpotato across different cultivation years. We observed that the microbial diversity and complexity of the fungal ecological network in rhizosphere soils of sweetpotato were decreased after 5 years of continuous cropping, with significant enrichment in Sphingobium , Gemmatimonas , Volutella, and Neoidriella . Tuber yield, soil pH, and available potassium (AK) content were significantly reduced after continuous cropping, with the soil microbial community having the highest correlation with pH, AK, and ammonium nitrogen (NH 4 + -N). Specifically, soil pH and AK were positively correlated with Bacillus and Gaiella, and negatively correlated with some plant-pathogenic fungi ( Volutella and Neoidriella ), while NH 4 + -N showed the opposite trend. In addition, soil pH, AK, and the relative abundance of Bacillus were positively correlated with tuber yield, while Volutella showed the opposite trend. In summary, the continuous cropping of sweetpotato negatively affects rhizosphere soil health, resulting in imbalanced soil fertility and increased abundance of pathogens. These results improve our understanding of factors driving obstacles faced with the continuous cropping of sweetpotato, enabling future studies and the development of technologies to overcome these obstacles.