Induction of systemic resistance and management of safflower Macrophomina phaseolina root-rot disease by biocontrol agents

Abstract

Three biocontrol agents such as Trichoderma harizianum, Pseudomonas fluorescens and Bacillus subtilis were isolated from safflower rhizosphere soil and tested individually for their effectiveness in controlling root-rot of safflower. Talc based formulations were prepared and treated the seeds at different concentrations for assessing their ability to induce plant growth and in turn control root-rot disease. Among bioagents, P. fluorescens and T. harzianum (10 g/kg) proved to be effective in controlling disease under laboratory, greenhouse and field conditions. The efficacy of these biocontrol agents are equivalent to the standard fungicide Bavistin (Carbedazim). Other than direct action of these biocontrol agents triggered defense related enzymes involved in phenyl proponoid pathways and phenols. Higher activity of peroxidase, phenylalanine ammonia-lyase, chitinase, polyphenol oxidase and β-1,3-glucanase was observed in P. fluorescens and T. harzianum treated safflower plants after challenge inoculation with M. phaseolina. Seed treatment with these biocontrol agents enhanced the seed germination and growth parameters against root-rot disease and they also induced systemic resistance and/or physiological changes leading to plant defense mechanisms.