Nanopriming technology for enhancing germination and starch metabolism of aged rice seeds using phytosynthesized silver nanoparticles

TLDR

Nanomaterials are a relatively new addition to agriculture compared to their established use in biomedical and industrial sectors. The study aims to develop a green‑synthesized, biocompatible silver nanoparticle nanopriming agent from kaffir lime leaf extract to improve germination of aged rice seeds. Nanopriming promotes germination by creating nanopores for water uptake, reactivating ROS/antioxidant systems, generating hydroxyl radicals to loosen cell walls, and acting as a nanocatalyst to accelerate starch hydrolysis. Phytosynthesized AgNPs at 5–10 ppm significantly increased germination, seedling vigor, α‑amylase activity, soluble sugar content, aquaporin expression, and ROS production, confirming their effectiveness as a nanopriming agent for aged rice seeds.

Abstract

Application of nanomaterials for agriculture is relatively new as compared to their use in biomedical and industrial sectors. In order to promote sustainable nanoagriculture, biocompatible silver nanoparticles (AgNPs) have been synthesized through green route using kaffir lime leaf extract for use as nanopriming agent for enhancing seed germination of rice aged seeds. Results of various characterization techniques showed the successful formation of AgNPs which were capped with phytochemicals present in the plant extract. Rice aged seeds primed with phytosynthesized AgNPs at 5 and 10 ppm significantly improved germination performance and seedling vigor compared to unprimed control, AgNO3 priming, and conventional hydropriming. Nanopriming could enhance α-amylase activity, resulting in higher soluble sugar content for supporting seedlings growth. Furthermore, nanopriming stimulated the up-regulation of aquaporin genes in germinating seeds. Meanwhile, more ROS production was observed in germinating seeds of nanopriming treatment compared to unprimed control and other priming treatments, suggesting that both ROS and aquaporins play important roles in enhancing seed germination. Different mechanisms underlying nanopriming-induced seed germination were proposed, including creation of nanopores for enhanced water uptake, rebooting ROS/antioxidant systems in seeds, generation of hydroxyl radicals for cell wall loosening, and nanocatalyst for fastening starch hydrolysis.