Biological control of rhizobacteria against rice diseases caused by Rhizoctonia solani (Sheath blight) and Sarocladium oryzae (Sheath rot)

Sheath blight and Sheath rot of rice caused by Rhizoctonia solani and Sarocladium oryzae is an economically important disease causing rigorous yield losses. Biological control of the disease using plant growth promoting rhizobacteria (PGPR) is a potential substitute to the presently available chemical control methods. The present investigation was aimed to study the plant growth promoting (PGP) activity and antagonistic activity of two rhizobacteria Pseudomonas fluorescence and Rhizobium sp., isolated from rhizosphere area of rice, against two major rice pathogens. In the present work IAA (Indole acetic acid production) was found maximum amount in Pseudomonas fluorescence (30 mg / ml) and trace amount in Rhizobium sp. Maximum amount of Siderophore production was noticed in both isolates. Pseudomonas fluorescence showed positive result for the HCN production but Rhizobium sp., was found to be negative and both bacterial isolates solubilized phosphate in very effective manner. Both rhizobacteria were found to produce ammonia and catalase. The cross streak studies revealed that the complete inhibition of mycelia growth of Rhizotonia solani (85%) and partial inhibition of Sarocladium oryzae (45%) against two rhizobacteria. Antifungal compound extracted from both rhizobacteria were found to exhibit maximum antagonism against rice pathogens. This result concluded that both PGPR’s can be used as best bio-control agent against rice pathogens instead of hazards chemicals.