Use of silver nanoparticles for managing Gibberella fujikuroi on rice seedlings

Abstract

It is of great interest for rice producers to develop novel seed disinfection methods with effective, less toxic, and environment-friendly active ingredients. This study evaluated silver nanoparticles (AgNP) as an alternative agent for seed treatment since elemental silver possesses strong antimicrobial properties and a low toxicity to humans and animals. AgNP (∼7.5 nm in diameter) solution was chemically synthesized and evaluated for antifungal activity against Gibberella fujikuroi as representing a seedborne fungal pathogen in rice (Oryza sativa). AgNP reduced viability of G. fujikuroi conidia by 50% when directly exposed to concentrations ranging from 0.015 to 1.5 μg mL−1 for 1 to 20 min. Rice seeds infested with G. fujikuroi and treated with 150 μg mL−1 of AgNP significantly decreased colony-forming units (CFU) of G. fujikuroi on the seed surface when treated for 10 min and up to 24 h. Seed treatment with 150 μg mL−1 AgNP for 12 or 24 h significantly improved seedling emergence and height of G. fujikuroi-infested seeds. Adverse effects on germination rate and seedling growth were not observed with any of the AgNP treatments (≤150 μg mL−1 for up to 48-h exposure) tested in this study. The antifungal effect of AgNP against G. fujikuroi attested in this study suggests that AgNP is a new antifungal ingredient that can be used for managing important seedborne fungal pathogens of rice.