Evaluating the biocontrol efficacy of selected plant growth promoting rhizobacteria against tomato bacterial wilt caused by Ralstonia solanacearum

Abstract

Tomato bacterial wilt, caused by the pathogen Ralstonia solanacearum, poses a significant threat to tomato production worldwide. The management of this devastating disease often relies on chemical pesticides, which can have adverse environmental and health impacts. In recent years, there has been growing interest in the use of plant growth promoting rhizobacteria (PGPR) as eco-friendly alternatives for disease control. This study aimed to evaluate the biocontrol efficacy of selected PGPR strains against tomato bacterial wilt. A total of ten PGPR strains were purified from soil samples and were assessed for their potential to promote tomato growth through various plant growth-promoting traits, such as production of indole-3-acetic acid (IAA), phosphate solubilization, and siderophore production. All the ten bacterial strains were screened for their ability to suppress the growth of R. solanacearum in-vitro using dual-culture assays. In greenhouse experiments, selected PGPR strains were applied as seed treatments and soil drenches to tomato plants infected with R. solanacearum. Disease incidence and biocontrol efficacy by PGPR were monitored throughout the study. Results revealed that several PGPR strains exhibited strong antagonistic activity against R. solanacearum in-vitro dual culture technique ranging from 0-34 mm zone of inhibition. The greenhouse trials demonstrated that the application of selected three PGPR strains alone and in consortium significantly reduced the disease incidence up to 5% as compared with control 71% of tomato bacterial wilt and have up to 64% biocontrol efficacy to inhibit R. solanacearum under greenhouse conditions. Overall, this study highlights the promising biocontrol potential of selected PGPR strains against tomato bacterial wilt caused by R. solanacearum. These findings suggest that the integration of PGPR-based biocontrol strategies into tomato production practices has the potential to reduce the reliance on chemical pesticides, promote sustainable agriculture, and minimizing the environmental impact of disease management.