Comparative efficacy of diffusible and volatile compounds of tea rhizospheric isolates and their use in biocontrol

ABSTRACT

An attempt was made to study in vitro production of antifungal substances by various strains of Bacillus subtilis and Pseudomonas corrugata. These strains were isolated from the rhizosphere of established tea Camellia sinensis L. located in North West Indian Himalayan regions viz Himachal Himalayas and Garhwal Himalayas. Selected strains were checked for their biocontrol potential against two phytopathogenic fungi Fusarium udum and Alternaria solani and the antagonists were found to cause inhibition in radial growth of the fungi. This diffusible effect was attributed to the production of diffusible and volatile compounds which were found to be potent antifungal in nature. The antifungal substances in bacterial strains were found to be extracellular; proteinacious in nature. The colony forming units (cfu) of pathogenic fungi were reduced by the diffusible and volatile compounds produced by antagonists. The inhibition in cfu was more by volatile compounds than by diffusible compounds. The volatile compounds included aldehydes; alcohols; ketones; sulphides and HCN