Application of plant growth-promoting rhizobacteria combined with compost as a management strategy against Verticillium dahliae in tomato

This study aimed to evaluate the effect of plant growth-promoting rhizobacteria (PGPR) and compost, applied alone or in combination, on tomato resistance to vascular wilt caused by Verticillium dahliae. Improved management of vascular wilt is important for enhanced productivity of greenhouse-grown susceptible tomato plants. The application of compost and PGPR resulted in a reduction in infection parameters compared with untreated plants inoculated with the pathogen, as well as activation of plant defence mechanisms. In the presence of the pathogen, compost application significantly improved the total fresh and dry weights by 97% and 71%, respectively, compared with pathogen-inoculated controls. The combination of compost with PGPR significantly increased chlorophyll fluorescence and stomatal conductance compared with the infected-control. In addition, the combination of compost and PGPR reduced the accumulation of stress markers such as malondialdehyde and hydrogen peroxide by 48% and 77%, respectively, and promoted the activity of antioxidant enzymes. Fruit yield and quality were also significantly improved relative to the control. The results suggest that compost applied alone or in combination with PGPR helps to suppress vascular wilt and to improve the yield and quality of tomatoes.