Relationship between antagonistic activities of Pseudomonas fluorescens isolates against Rhizoctonia solani and their production of lytic enzymes

Various strains of Pseudomonas fluorescens were isolated from the rhizosphere of rice. Among the eight isolates tested in vitro, five isolates were found to inhibit mycelial growth of the rice sheath blight pathogen Rhizoctonia solani. Among the five isolates, PF-21 was the most effective one in inhibiting the growth of R. solani in vitro and in controlling rice sheath blight under greenhouse conditions. The eight P. fluorescens isolates chitinase and β-1,3-glucanase when grown on medium containing chitin and laminarin, respectively. The highest chitinase activity was seen with isolate PF-21. Significant relationship between antagonistic activity of P. fluorescens and their level of chitinase production was observed.