Efficacy of Some Probiotic Rhizosphere Bacteria Against Seed Borne Fungi of Brri Dhan46

We investigated the prevalence of seed borne fungal pathogens in rice variety BRRI Dhan46 and to evaluate the efficacy of antagonistic bacteria in controlling seed borne disease. A composite sample of BRRI Dhan46 was assayed. Five seed borne fungi viz. Fusarium sp., Bipolaris oryzae, Curvularia sp., Gliocladium sp. and Aspergillus flavus were isolated from the rice seeds. Fifteen probable antagonistic bacterial isolates were isolated from rhizosphere soil and screening was done to detect the most suitable antagonistic bacterial isolates against seed borne fungi of rice. Seeds of rice variety, BRRI Dhan 46 yielded 21.5% Fusarium sp., 6.25% Bipolaris oryzae, 4.75% Curvularia sp., 0.25% Gliocliodium sp. and 3.5% Aspergillus flavus infection in blotter method. Among fifteen isolates six isolates (Iso-1, Iso-2, Iso-3, Iso-5, Iso-7 and Iso-10) were found to be effective in dual culture method. In dual culture method, the bacterial Iso-2 produced higher inhibition of mycelia. Bacterial antagonist Iso-2 performed better than other isolates on seed borne fungal prevalence in blotter method. Seed treated with Iso-2 completely controlled seed borne Bipolaris oryzae, Aspergillus flavus and Gliocladium sp. The highest seed germination (98%) was recorded in seeds treated with Iso-2 and Iso-1. In water agar test tube method, the highest germination (96.67%) was found in Iso-2 treated seed. Iso-2 treated seed gave the highest Vigor Index (1424) and the lowest vigor index was noted (753) in untreated control in rolled paper towel method.