Effects of Bacillus subtilis NCD-2 and broccoli residues return on potato Verticillium wilt and soil fungal community structure

Abstract

Potato Verticillium wilt is an economically important disease that significantly decreases tuber yield. Biological control is an effective approach for controlling potato Verticillium wilt. The objective of this study was to evaluate the effects of treatment with Bacillus subtilis NCD-2 (BS), broccoli residues (BR), and combination among them (BB) on potato Verticillium wilt and the soil fungal community structure. Field experiments demonstrated that BS, BR and BB successfully suppressed potato Verticillium wilt, achieving control effects of 32.25%, 48.15%, and 37.85%, respectively. Compared to the untreated control, potato yield increased by 10.38%, 16.82% and 27.12% after the treatments of BS, BR and BB, respectively. Moreover, the BS treatment did not decrease the rhizosphere V. dahliae population, which was significantly decreased by BR (19.08%) and BB (30.46%). Illumina MiSeq analysis showed that soil fungal diversity in the rhizosphere was decreased under BS, BR and BB. Principal component and heatmap analyses showed that BS exerted a similar effect on the fungal community structure to the blank control. However, BR and BB greatly changed the fungal community structure. Moreover, the relative abundance of beneficial microbes such as Chaetomium and Mortierella was higher in the BS and BB soils than in the control. Redundancy analysis (RDA) showed that the fungal community structure under BR and BB was positively correlated with SOM, pH, AP and IP, while the opposite trend was observed under BS. The results suggested that BS seed treatment and BR return could be a useful strategy for potato production in sustainable agriculture; this research may provide a theoretical basis for understanding the mechanism of the ecological control of potato Verticillium wilt.