Effects of different crop rotations on the incidence of cotton Verticillium wilt and structure and function of the rhizospheric microbial community

Aims Cotton continuous cropping might cause the soil-borne disease Verticillium wilt in agricultural pro-duction. Crop rotation has been shown to be an effective method for controlling this disease. The objectives of this study were to evaluate the effects of cotton-maize rota-tion (CMR) and cotton-maize-broccoli residues rotation (CMBR) on incidence of cotton Verticillium wilt (CVW), soil microbial community structure and function.Methods qPCR was used to determine the populations of V. dahliae. Soil microbial community structure and function was analysed using metagenomics analysis. Results Results demonstrated that the disease inci-dence significantly decreased by 87.19% and 98.93%,and the populations of V. dahliae decreased by 67.07% and 84.36% under the CMR and CMBR treatments, respectively. There were significantly differences in bacterial communities under the CMR and CMBR treatments. Redundancy analysis revealed that the structures of microbial communities were mainly driven by available potassium (AK) and pH. Spearman's correlation analysis showed that most of KEGG pathways in bacterial community were negatively with pH, positively with NH4(+)-N and AK. The abundances of NifH, AmoA, NirK, and NarG genes (involved in nitrogen cycling), PfkABC, FbaB, PGAM and KdpgA genes (car -bon cycling), and Sir, Sat, and CysND (sulfur cycling) were enriched by the CMR and CMBR treatments.Conclusions CMR and CMBR could change the bacte-rial community structure and nutrients cycling in cotton rhizosphere, decrease the populations of V. dahliae in soil, therefore significantly reduce the incidence of CVW.

Automated summary

Cotton-maize rotation and cotton-maize-broccoli residue rotation can effectively control the incidence of cotton Verticillium wilt by reducing the populations of V. dahliae in soil. These rotation methods also impact the bacterial community structure and nutrient cycling in the cotton rhizosphere, leading to the enrichment of beneficial microbial populations.