Effects of restructuring tilth layers on the occurrence of Verticillium wilt and the soil microbial community in a continuous rotary tillage cotton field

Abstract

Background Restructuring tilth layers (RTL) is a tillage method that exchanges the 0–20 cm and 20–40 cm soil layers that can be applied during cotton cultivation to inhibit Verticillium wilt. This inhibitory effect may be related to changes in the soil microbial community after RTL. Therefore, we investigated the distribution of microbial communities after rotary tillage (CK) and RTL treatments to identify the reasons for reduction of Verticillium wilt in cotton fields subjected to RTL. Results Illumina high-throughput sequencing was used to sequence the bacterial 16S rRNA (V3–V4) and fungal internal transcribed spacer (ITS2) genes at soil depths of 0–20 and 20–40 cm. The incidence rate and incidence index of Verticillium wilt decreased by 28.57% and 42.64%, respectively, after RTL practice relative to CK. Moreover, RTL significantly enhanced the richness and evenness of bacteria at 20–40 cm and narrowed the difference in fungal evenness and richness between soil depths of 0–20 and 20–40 cm. The number of Verticillium dahlia decreased, while the relative abundance of biocontrol bacteria such as Bacillus and Pseudoxanthomonas increased significantly. Conclusion RTL improved bacterial diversity, decreased the number of Verticillium dahliae and increased the relative abundance of biocontrol bacteria, which may have suppressed the occurrence of Verticillium wilt in cotton fields.