Antagonistic Potencies of Native Papaya (Carica papaya L.) Rhizosphere Microflora Against the Root Rot Disease-Causing Pathogen - Fusarium solani

Aims: This study aims to isolate and identify rhizobacteria with antagonistic activities towards soil-borne fungi. Background: This research investigates the interactions between rhizospheric microorganisms and Fusarium solani, which causes root rot in papaya, within the agro-ecological context of Bihar. Nonetheless, there is a paucity of knowledge regarding the precise mechanisms through which rhizomicroflora suppress these pathogens, as well as the variety of rhizospheric species that play a role in this process. Methodology: The study, carried out in the 2022-23 timeframe at the ICAR-AICRP on Fruits experimental field and the Fruit Pathology Laboratory at RPCAU Pusa in Bihar, India, initiated with the isolation of 48 unique rhizospheric microbial isolates (comprising 38 bacterial and 10 fungal strains), which were evaluated for their antagonistic properties against Fusarium solani in vitro. Subsequent analysis revealed seven bacterial isolates exhibiting an antagonistic potential exceeding 85%. Findings: The results indicated that isolate RB-34 demonstrated a notably high inhibition efficacy of 93.85%, comparable to RB-29 at 91.00%. This was followed by RB-25 at 89.30%, RB-32 at 86.48%, RB-15 at 83.96%, RB-24 at 80.70%, and RB-13 at 79.39% when compared to the control. In contrast, isolate RB-33 exhibited the lowest inhibition percentage at 59.89% against Fusarium solani, highlighting its potential in addressing root rot. The experiment was conducted under controlled laboratory conditions and utilized a completely randomized design (CRD and FCRD). Data analysis was performed using one-way ANOVA with Past 4.0 software to evaluate the results obtained from the experiments. Conclusion and Recommendation: The isolates RB-34 demonstrated remarkable antagonistic effectiveness, achieving a rate of 93.85% against the mycelial growth of Fusarium solani. Consequently, this research highlights a promising solution for farmers facing challenges related to pathogen-induced root rot, thereby facilitating the development of environmentally sustainable and efficient disease management strategies. These results contribute to our comprehension of rhizospheric biodiversity and its potential role as biocontrol agents in sustainable agricultural practices.