Trichoderma Asperellum mediated synthesis of silver nanoparticles: Characterization and its physiological effects on tea [Camellia sinensis (L.) Kuntze var. assamica (J. Masters) Kitam.]

Silver nanoparticles (Ag NPs) were synthesized using culture filtrate of fungal antagonist Trichoderma asperellum for which silver nitrate was used as the precursor and were characterized by using UV-Vis spectroscopy, DLS, Zeta sizer, TEM and EDX. The physiological effects of Ag NPs on the host crop i.e. tea (clone-TV21) was evaluated at 100% concentration by introducing into the host with five different treatment methods viz. cutting treatment (one leaf bud cutting), injection method, foliar spray, soil application and seedling root dip treatment with 10 replicates for each. Observation on changes in chlorophyll content, moisture content, relative water content, total soluble sugar, total protein, lipid peroxidation (MDA content), secondary metabolites viz. phenol, alkaloid, and flavonoid were analyzed after 45 days of the treatment. Results showed that silver nanoparticles can induce the plants in increasing all the studied physiological parameters. Out of all the five treatments, foliar spray followed by seedling root dip treatment was found to be the best treatment for establishing silver nanoparticles in the plant system with maximum positive effects on all the parameters compared to other treatments and as control.