Field application of two plant growth promoting rhizobacteria with potent antifungal properties

Two bacterial strains VBLR10 and VBLR39 were identified for their anti-fungal properties from the rhizosphere of healthy Solanum lycopersicum (tomato) plants in a wilt infested field of Binuria, West Bengal and showed maximum sequence similarities with Bacillus subtilis and Cellulosimicrobium cellulans respectively in 16 s rRNA gene sequence homology. The strains showed excellent plant growth promoting activities in small field trials and antifungal activity in the laboratory against Alternaria alternata, Helminthosporium oryzae, Penicillium digitatum and Fusarium oxysporum producing prominent zones of inhibition on agar. Cell free supernatants of both VBLR10 and VBLR39 could reduce radial mycelial growth of Fusarium oxysporum when they were used to poison the growth medium. VBLR39 was also found to produce siderophore in a qualitative assay. Both strains survived for more than one year in alluvial soil sample at 28 °C and at 37 °C. The efficiency and applicability of the strains under field conditions were also established conclusively as they improve growth and yield parameters of Solanum lycopersicum (tomato) and Solanum melongena (brinjal) plants both qualitatively and quantitatively.