Dose-dependent responses to salinity stress in Zea mays following green-synthesized nZVI seed nanopriming

Salinity stress reduced germination, water uptake, seedling vigour, growth, photosynthetic pigments, protein and carbohydrate contents and root metabolic activity, while increasing proline accumulation, antioxidant enzyme activities and relative membrane-associated injury. Green-synthesized nZVI seed nanopriming generally improved these responses, with effects varying among endpoints and salinity levels. 40 ppm frequently performed better under non-saline and moderate salinity, whereas 20 ppm was more effective for several parameters under severe salinity; no single concentration was optimal across all endpoints. AAS showed increased total tissue-associated iron, with greater accumulation generally in roots, but could not establish intact nanoparticle internalization, uptake efficiency, or translocation. Overall, nZVI nanopriming improved several germination, physiological, biochemical and early-growth responses in Zea mays under the tested conditions. These findings are limited to one maize genotype and short-term Petri-dish and pot experiments conducted in a single experimental run; further studies are needed to assess nanoparticle fate, iron speciation, underlying mechanisms, long-term performance and field applicability.