Influence of rhizospheric bacteria on disease suppression and yield of tomato under Sclerotium rolfsii stress during rainy and dry planting season

Abstract

Agrochemicals used in controlling plant diseases are costly and their application is not sustainable, hence, the adoption of biological approaches. Microbial inoculants were screened in cycles under Sclerotium rolfsii stress to select host-mediated microbiota (HMM) and isolate rhizospheric bacteria with biocontrol potentials. Microbial isolates were evaluated in-vitro and on field under S. rolfsii stress. Results showed that microbiota inoculant significantly reduced disease severity till the 6th round. Identified isolates (Bacillus cereus, B. thuringiensis, B. mycoides and B. tropicus) displayed varying inhibitory effects against the growth of S. rolfsii in-vitro. During field trial, disease severity was significantly (P ≤ 0.05) reduced in all treatments by 71-85% (dry season) and 25-75% (rainy season) than the control (0%). However, the fruit weight of harvested tomatoes from plants treated with HMM (238g, 464g) and B. cereus AN14 (209g, 390g) were the most significant in dry and rainy seasons. These inoculants should be considered a biocontrol agent for diseases caused by S. rolfsii.