Antifungal Activity of Plant Growth Promoting Rhizobacteria Against Fusarium oxysporum and Phoma sp. of Cucurbitaceae

Cucurbitaceae is the largest group of summer vegetables which includes about 118 genera and 825 species and most of which are known to possess medicinal values. Several major pathogens are known to infect cucurbits and cause yield loss up to 70–80 %. Among them, Fusarium wilt and black rot are prevalent in and around Mysore, Karnataka, India. Plant growth promoting bacteria (PGPR) in the rhizosphere, enhances plant growth by exerting their beneficial effects through metabolites that directly or indirectly influence the plant growth. In the present study, seven bacterial isolates were isolated from the rhizosphere soils of Cucurbitaceae crops near Mysore, India. The bacterial isolates were identified based on the morphological and biochemical tests. The root rot pathogen Fusarium oxysporum and black rot causing Phoma sp. were isolated from Cucurbitaceae crops. The antifungal activity of PGPR isolates against F. oxysporum and Phoma sp. was studied by dual culture assay. All the isolates were screened for their plant growth promoting traits such as phosphate solubilisation and ability to produce—indole acetic acid (IAA), siderophore, hydrogen cyanide (HCN) and enzymes. The PGPR strains showing more than two traits also showed good antifungal activity against F. oxysporum and Phoma sp. An increase in the growth rate accompanied by decreased disease intensity was noticed in the plants treated with selected PGPR