Evaluation of bio efficacy of Pseudomonas fluorescens against soil borne plant pathogen

Abstract

In the present study, the in vitro antagonistic potential of Pseudomonas fluorescens seven isolates was evaluated against major soil-borne pathogens including Fusarium oxysporum f. sp. ciceri, Rhizoctonia bataticola, Rhizoctonia solani, and Sclerotium rolfsii. Bioefficacy was evaluated by dual culture assay were conducted on three media King’s B (KB), Potato Dextrose Agar (PDA), and a 1:1 combination of KB and PDA. The mixed KB+PDA medium consistently showed greater pathogen suppression compared to either KB or PDA alone. Among the isolates, Pf 2 exhibited the strongest antagonistic activity. Against F. oxysporum f. sp. ciceri, Pf 2 achieved inhibition levels of 79.84% on KB+PDA, 76.21% on KB, and 59.46% on PDA, while Pf 7 was the least effective across all media. For R. bataticola, Pf 2 recorded 73.78% inhibition on KB+PDA, whereas Pf 1 showed 63.88% inhibition on KB and Pf 2 achieved 47.03% on PDA. In the case of R. solani, Pf 2 suppressed growth by 77.52% on KB+PDA, 73.92% on KB, and 40.74% on PDA. Against S. rolfsii, Pf 2 demonstrated 81.60% inhibition on KB+PDA, 65.38% on KB, and 52.22% on PDA. Overall, isolates Pf 1 through Pf 5 displayed promising biocontrol potential, while Pf 6 and Pf 7 were comparatively less effective.