Phytotoxicity study of silver nanoparticles on the germination of water spinach (Ipomoea aquatica Forsk.) and mustard green (Brassica rapa L.) seeds

Silver nanoparticles (AgNPs) are metal nanoparticles used in many applications in the healthcare and industrial fields. The use of AgNPs worldwide can reach 500 tons annually, potentially increasing. The release of silver metals into the environment causes pollution in the aquatic environment and bioaccumulation in organisms. Our previous research successfully synthesized AgNPs through a biosynthetic method using Diospyros discolor Willd. (velvet apple) leaf extract. Therefore, this study aimed to determine the phytotoxic effects of biosynthetic AgNPs on water spinach (Ipomoea aquatica Forsk.) and mustard greens (Brassica rapa L. var. caisin) seeds. This study includes five groups, i.e., distilled water as a negative control, 10 mM AgNO3 as a positive control, and biosynthesized AgNPs at concentrations of 30, 40, and 50 mg/L. The seeds were soaked for 24 h in the AgNPs and germinated for 14 days to observe the symptoms of phytotoxicity. Seeds germination was assessed according to the germination rate (%), germination rate index, fresh and dry weight, and plant height. The results showed that the AgNPs had a toxic effect on B. rapa. Meanwhile, exposure to AgNPs did not affect I. aquatica germination. The result showed that each type of plant could have different responses to the exposure of AgNPs.