Silver nanoparticles as a potential nematicide against Meloidogyne graminicola

Plant-parasitic nematodes cause severe damage to the various agricultural crops, leading to economic losses for farmers. Therefore, identification and development of novel and environmentally benign nematicides is critically important. In this study, a silver nanoparticle (AgNP) formulation was synthesized, characterized, and investigated as a potential nematicide against rice root-knot nematode, Meloidogyne gramnicola, on rice (Oryza sativa). A series of lab assays (water and sand screening) and glasshouse experiments (using soilless system, autoclaved soil, and naturally infested soil) were conducted to examine the nematicidal effects of AgNP. The results from lab assays revealed 0.1 µg/ml as the minimum concentration for 100% irreversible nematode mortality after 12 hr in the water screening test. However, results from the sand screening test indicated 100% nematicidal effect of AgNP at 2 µg/ml after 24 hr of incubation. In glasshouse assays in soilless system of rice cultivation, 1 µg/ml concentration of AgNP applied directly to the trays achieved significant suppression of root gall formation. The effective dosage to kill nematodes in field soil assays was determined to be 3 µg/ml, which is lower than the value of 150 µg/ml reported in the literature. No visible adverse effect of AgNP was observed on seed germination or plant growth in all the experiments. The results indicate that AgNP has effective nematicidal activity against M. graminicola in rice.