Screening and Characterisation of Pseudomonas fluorescence: A Biological Control Agent against Wilt Fungus in Cajanus cajan (L.) Millsp.

About 310 Pigeon pea (Cajanus cajan (L.) Millsp.) rhizobacteria were isolated from cultivated soils of North-East India (Alwar district, Rajasthan). Among the total isolates, 25 isolates were confirmed as Pseudomonas fluorescence based on the biochemical tests, such as arginine hydrolysis, catalase activity, production of fluorescing compounds, gelatin liquefaction and growth at 4°C and 42°C. Their antifungal activity against wilt fungus Fusarium udum (strain of pigeon pea) was examined in vitro and in vivo. Survivality of the isolates under stress conditions of temperature and pH was examined. Five strains (BISR-E, BISR-T, BISR-V, BISR-X and BISR-Y) gave maximum temperature tolerance and four strains (BISR-B, BISR-C, BISR-D and BISR-H) could survive under variable pH range 4–10. Twelve isolates of P. fluorescence were exhibited strong antifungal activity against F. udum. Zone of inhibition was measured. Twelve isolates were observed with more than 30% RI value with maximum RI value recorded in strain BISR-W and BISR-N (42.0%). Net house pot studies screening results revealed that 17 isolates (BISR-A, BISR-B, BISR-C, BISR-D, BISR-E, BISR-G, BISR-H, BISR-I, BISR-K, BISR-L, BISR-N, BISR-O, BISR-P, BISR-R, BISR-U, BISR-W and BISR-X) were observed as good plant growth-promoting rhizobacteria and biological control agents. Among these strains, isolate numbers BISR—B, BISR-F, BISR-K, BISR-N, BISR-O, BISR-P, BISR-W and BISR-X were proved themselves superior isolates having good biocontrol potential to manage F. udum in Pigeon pea plant and to enhance plant growth parameters to a significant level. Out of 25 isolates, 20 isolates (BISR-A, BISR-B, BISR-C, BISR-D, BISR-F, BISR-G, BISR-H, BISR-I, BISR-J, BISR-K, BISR-L, BISR-M, BISR-N, BISR-O, BISR-P, BISR-Q, BISR-R, BISR-S, BISR-T and BISR-V) could produce siderophore.