Inducing systemic resistance in cotton plants against charcoal root rot pathogen using indigenous rhizospheric bacterial strains and chemical elicitors

This study was carried out to screen some indigenous rhizospheric bacterial strains and chemical elicitors for their capacity to antagonize and induce systemic resistance to control charcoal root rot of cotton under both greenhouse and field conditions. Twenty rhizospheric bacterial strains and five chemical elicitors were used for resistance induction under greenhouse evaluations. Two Bacillus strains viz., B. megaterium ZMR-4 and B. subtilis IAGS-174 and one chemical elicitor Benzothiadiazole provided highest control over charcoal rot under greenhouse conditions. Increase in quantities of defense related biochemicals as total phenolics and enzymes including peroxidases polyphenoloxidases and phenylalanine ammonia lyase confirmed induced systemic resistance (ISR) phenomenon in cotton plants treated with selected bacterial strains and chemical inducers. Talc based formulations of these two strains were prepared to assess their effectiveness under field conditions. These not only provided protection against charcoal root rot, but also markedly enhanced growth and fruit yield of plants under field conditions. The study clearly indicated the significance of B. subtilis IAGS-174 and B. megaterium ZMR-4 along with Benzothiadiazole for inhibition of charcoal root rot and growth promotion of cotton in our cultivation system.