Ankit Kumar Singh, Ramji Singh, Prashant Mishra and Brijesh Kumar
Abstract
Sheath blight, caused by the fungus Rhizoctonia solani, is a devastating disease that poses a significant threat to rice production worldwide. In recent years, biocontrol agents such as Trichoderma and Pseudomonas have gained attention for their potential to manage sheath blight while minimizing the environmental impact associated with chemical pesticides. The present investigation assessed the effect of Trichoderma harzianum and Pseudomonas fluorescens on Rhizoctonia solani in vitro after collection and mass multiplication from different locations. The dual culture assay revealed complex interactions between R. solani and biocontrol agents such as T. harzianum and Pseudomonas fluorescens. T. harzianum exhibited significant antagonistic activity, as evidenced by the inhibition of R. solani growth, hyphal coiling around R. solani mycelia, and direct mycoparasitic interactions. Pseudomonas fluorescens, on the other hand, demonstrated an indirect antagonistic effect by producing siderophores and antibiotics that hindered the growth of Rhizoctonia solani. Trichoderma harzianum isolate (IRRI-1) was found to be most inhibitory for Rhizoctonia solani in vitro followed by Trichoderma harzianum (SV-3) and Pseudomonas fluorescens (PF-2). These observations provide insights into the mechanisms underlying the biocontrol potential of T. harzianum and Pseudomonas fluorescens against R. solani. In conclusion, the dual culture assay proved to be an effective method for studying the interactions between R. solani and biocontrol agents. The findings contribute to our understanding of the underlying mechanisms of biocontrol agents and offer valuable information for the development of sustainable agricultural strategies aimed at managing plant diseases caused by R. solani.