Nanopriming with zero valent iron (nZVI) enhances germination and growth in aromatic rice cultivar (Oryza sativa cv. Gobindabhog L.).

Engineered nanoparticles are utilized in agriculture for various purposes. They can be used as fertilizer, carrier for macro/micro nutrients or priming agents. Various nanoparticles are reported to have toxicity at very high doses, but at optimum concentration, they can be beneficial for plant growth and development. In the present study, low concentrations of nZVI nanoparticles were evaluated for their growth enhancement potential as seed priming agent in an aromatic rice cultivar, Oryza sativa cv. Gobindabhog. Seeds were primed with different concentrations (10, 20, 40, 80, 160 mg L-1) of nZVI and allowed to grow for 14 days. Seed germination and seedling growth were studied by assessing physiological, biochemical, and structural parameters at different time points. Maximum activities of hydrolytic and antioxidant enzymes, along with root dehydrogenase enzyme were observed in 20 mg L-1 nZVI primed seeds. Priming with low doses of nZVI increased seedling vigour, as expressed by increased root and shoot length, biomass and photosynthetic pigment content. Our study also confirmed that after 14 days growth, the seedling showed absence of membrane damage, reduction in proline level and anti-oxidant enzyme activities. However, seedlings primed with 160 mg L-1 nZVI suffered oxidative stress. SEM micrographs also revealed damage in root tissue at that concentration. AAS study confirmed uptake of nZVI by the rice plants as maximum level of iron was found in the plants treated with highest concentration (i.e. 160 mg L-1 nZVI). Thus, nZVI at low concentrations can be considered as priming agent of rice seeds for increasing plant vigour.