Plant growth promoting and antagonistic potential of indigenous PGPR from tomato seedlings grown in mid hill regions of Himachal Pradesh

Abstract

A total of 859 rhizobacteria and 574 endorhizobacterial isolates were obtained from different tomato growing sites of Himachal Pradesh, India. Predominant population of rhizo and endorhizobacteria with respect to sites showed variations and their population growth was observed to be higher on nutrient agar than on Pikovskaya medium. All the isolates were screened for their plant growth promoting attributes and only 17 isolates were found to be efficient phosphate solubilizers with 15 mm or more halo zone formation on PVK medium. These efficient isolates were further screened for their ability to fix atmospheric nitrogen by growing them on nitrogen free medium as well as for their antifungal activity against two fungal pathogens of tomato i.e. Fusarium oxysporum and Rhizoctonia solani. Out of total, 58.82% were found to be nitrogen fixers while 52.94% bacteria showed inhibition against selected soil borne pathogens. Morphological and biochemical characterization showed colonization of Bacillus sp. along with Pseudomonas sp., Enterobacter sp., Acinetobacter sp. and some unidentified P-solubilizing bacteria in the tomato rhizosphere.