ANIL KUMAR, PCHIRANJEEVI, N2018-05-162018-05-162016http://krishikosh.egranth.ac.in/handle/1/5810046311D5345In detached leaf technique inoculation with two days old culture disc of R. solani initiated sheath blight disease of rice swiftly than sclerotial body inoculation. In rolled towel paper method, with seed inoculation of R. solani, 16.7% germination, 38.9% shoot length, 48.2% root length and 52.7% vigour index was reduced. Two of the eight Pseudomonas fluorescens isolates tested in dual culture against R. solani, viz., PF-2 and PF-5 were found potentially antagonistic in vitro sustaining inhibitory effect. Two of the six Trichoderma isolates viz., ET-1 and RT-4 were found potentially antagonistic with complete overgrowth on R. solani under in vitro. All the four test antagonistic isolates and the pathogen could convert silver in to bionano silver with absorbance peaks around 400 to 450 nm. Exponential growth of the organism was found efficient in nano conversion, especially in case of P. fluorescens. Cellulose among the five carbon sources and casein among the five nitrogen sources used as nutrients were found to support better in nanoconversion by Trichoderma ET-1. Ethyl acetate and Diethyl ether extracts of ET-1 culture filtrate were found to contain nanoconversion principle with 0.0298% and 0.0154% as dilution end points respectively. Zeta potential of P. fluorescens PF-2 based bionano silver particles prepared from 5 day old culture filtrate was -34.4 mV, R. solani based nano particles prepared from 5 day old culture filtrate was -36.0 mV and Trichoderma ET-1 based nano particles from 5 day old culture filtrate was -0.3mV indicating rapid coagulation and flocculation property of ET-1 based nano preparation. Dynamic light Scattering spectroscopy revealed that bionano silver particle size ranged from 80 to 137.4nm (98.2±28.7nm) with PF-2 based nano and 98.8 to 223.7nm (160.9±62.1nm) with R. solani based nano indicating more of polydisperse in nature. In case of bionano silver prepared from ET-1 culture filtrate, the particle size ranged from 6.3 to 6.9nm (6.7±0.3nm) indicating its monodisperse nature. Results of SEM analysis was also in line with DLS analysis. Bionano preparations, irrespective of the isolate source used, were found effective in decreasing the sheath blight incidence in vitro though variation existed in terms of quantum of disease reduction. Satisfactory reduction in disease development at 100% and 50% concentrations of bionano silver was obtained compared to 10%. Bionano preparations were effective against all the three selected test isolates of R. solani, Trichoderma and P. fluorescens though the inhibition was much pronounced on bacterial culture. Increased germination of rice seeds, shoot length, root length, S:R ratio, fresh weight, dry weight and vigour index of rice seedlings with 10% silver bionano preparations applied as seed treatment (wet seed treatment for 10 minutes) was observed. Plant defense related enzymes viz., peroxidases, polyphenol oxidase, phenyl alanine ammonia lyase and tyrosinase were substantially accumulated in treated rice seedlings indicating induction of resistance mechanism in rice seedlings.en-USnullThesis