Functional Characterization and In vitro Efficacy of Chickpea Rhizobacteria against Collar Rot and Dry Root Rot

Abstract

Background: Chickpea productivity is severely constrained by soil-borne fungal pathogens Sclerotium rolfsii and Rhizoctonia bataticola, which cause collar rot and dry root rot. This study explores the chickpea rhizosphere for beneficial bacteria, that suppress these pathogens and promote plant growth. Aim: To isolate and functionally characterize rhizobacterial isolates antagonistic to collar rot and dry root rot pathogens. Methodology: Microbial isolates were isolated from chickpea rhizosphere by standard serial dilution and plating. Antagonistic activity was screened in vitro via dual culture assays, recording percent mycelial growth inhibition. Morphological, biochemical and plant growth promoting (PGP) traits were characterized. Biochemical and PGP traits data was assessed using hierarchical cluster analysis and Principal Component Analysis (PCA). Results: A total of 223 rhizobacterial isolates were obtained. Ten isolates were highly effective against S. rolfsii, with RCA-05 (72.9±0.09), RSA-02 (72.5±0.12), BSA-17 (72.9±0.07) and BSA-14 (72.5±0.10) exhibiting highest inhibition. Against R. bataticola, 11 isolates exceeded 40% inhibition of mycelial growth, among which BSA-33 (47.9±0.03) and RCA-05 (47.1±0.12) were being the most effective. Multivariate analysis identified BWA-01, RSA-5, and RCA-08 were associated strongly with multiple beneficial traits.  Conclusion: The study identified promising PGP actinomycetes and bacteria that simultaneously promote plant growth and suppress soil-borne pathogens, offering a sustainable bioinoculant solution for chickpea cultivation.