Green-synthesized silver nanoparticles for improved heat stress resilience and germination in potato seeds

Climate change-induced heat stress severely impedes potato (Solanum tuberosum) germination, threatening global food security. Here, we report the application of green-synthesized silver nanoparticles (AgNPs), fabricated using Azadirachta indica (neem) leaf extract, as nanopriming agents to enhance germination and thermotolerance. The green-synthesized AgNPs exhibited a smaller crystallite size (9.7 nm) compared to chemically synthesized AgNPs (20.6 nm), with higher colloidal stability (zeta potential -55.2 mV vs. -35.7 mV). At the optimal priming concentration (5 mg L^-1), green AgNPs increased germination on the 12th day by 19% relative to chemical AgNPs and by 50% over hydroprimed controls. Under elevated temperature (32.2 °C), green AgNP-primed seeds maintained a consistent 10% higher germination rate than controls and showed faster radicle emergence. ICP-MS confirmed greater nanoparticle uptake in primed seeds (144 ppm Ag for green AgNPs vs. 105 ppm for chemical AgNPs, compared to 1.98 ppm in hydroprimed seeds). Enhanced water uptake was also evident, with an 82% increase in seed mass after green AgNP priming compared to 44% in hydroprimed seeds. A preliminary techno-economic analysis confirmed the superior cost-effectiveness of the green synthesis route. Collectively, these findings establish green-synthesized AgNP nanopriming as a cost-effective, sustainable, and biologically superior strategy to improve potato germination and heat stress resilience, offering a promising avenue for climate-smart agriculture.