Studies on Management of Sheath Blight in Rice Using Different Isolates of Pseudomonas Fluorescens and Trichoderma Harzianum

Abstract

Rice (Oryza sativa L.) is the primary and staple food for human being all over the world. This crop is subjected to attack by a number of diseases and sheath blight of rice caused by the Rhizoctonia solani alone is responsible for a loss of 1.2 to 69% in the rice yield in India. The present investigation was conducted to assess the effect of Trichoderma harzianum and Pseudomonas fluorescens on Rhizoctonia solani in -vitro and also its effect on rice crop growth and disease development under pot experiment. 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). Maximum plant height in rice was recorded due to seed bio-primmed and seedling root dip as well with T. harzianum (IRRI-1) followed by T. harzianum (SV-3) and Pseudomonas fluorescens (PF- 2). All these isolates were also resulted in highest enhancement of chlorophyll content in rice plants, either as seed bio-primming or as seedling root dip. Maximum root length in rice plants were also noticed due to seed biopriming with T. harzianum (IRRI-1), T. harzianum (SV-3) and P. fluorescens (PF-4). These isolates were also most effective in promoting growth of, rice root when applied through seedling root dipping to the rice crop. Maximum shoot length in rice plants were supported by seed biopriming and seedling root dipping with T. harzianum (IRRI -1) and T. harzianum (SV-27) and P. fluorescens (PF-2). Both the method of delivery, i.e. Seed biopriming and seedling root dipping with Trichoderma harzianum (IRRI-1) followed by Pseudomonas fluorescens (PF-4) and Trichoderma harzianum (SV-3) resulted in highest root fresh weight and dry weight of root as well. Highest fresh weight and dry weight of rice shoot rice were noticed in the plants bio-primmed with Trichoderma harzianum (IRRI 1), Trichoderma harzianum (SV-26) and Pseudomonas fluorescens (PF2). Effectiveness of seedling root dipping with these bioagents were in same order as in case of seed biopriming. Highest reduction in the level of sheath blight disease in rice were observe in the plants bio-primmed with Trichoderma harzianum (IRRI-1), Trichoderma harzianum (SV-3) and Pseudomonas fluorescens (PF4) and effectiveness of these bioagents were in little different when applied as seed ling root dip where Trichoderma harzianum (IRRI 1) followed by Pseudomonas fluorescens (PF4) and Trichoderma harzianum (SV-19) were the most effective isolates in reducing the level of sheath blight disease in rice. Over all it was noticed that seed biopriming is comparatively more effective than seedling root dipping for growth promotion in rice whereas seedling root dipping is comparatively more effective than seed biopriming for sheath blight disease management.