Antifungal Activity of Biogenically Synthesized Silver and Gold Nanoparticles Against Sheath Blight of Rice

Abstract

Biogenically synthesized silver and gold nanoparticles were evaluated for antifungal activity against Rhizoctonia solani causing sheath blight of rice. Both the nanoparticles were tested at 1, 5, 10, 50, 100 and 200 ppm along with chemical check against the pathogen. Silver nanoparticle (Ag NP) at 200 ppm showed the highest inhibition (73.39%) in the radial growth of R. solani, while gold nanoparticle (Au NP) at the same concentration inhibited the growth of the pathogen up to 60.83%. Study on mode of action of nanoparticle by electron microscopy showed that Ag NP accumulate inside the fungal cells thereby cause distortion of fungal cells leading to death of the pathogen. Ag NP at 200 and 100 ppm caused complete inhibition of sclerotial germination of R. solani. Pot experiment conducted to study the efficacy of Ag NP at 200 ppm against sheath blight of rice showed that application of Ag NP increased the plant growth parameters as compared to control, with reduced per cent disease incidence (20.00%) as compared to inoculated control R. solani (88.00%). Application of Ag NP also increased the concentration of vital secondary metabolites like phenols, flavonoids, terpenoids and total soluble sugars.