Zinc Oxide Nanoparticles and magneto-priming in Triticale: Environmental Behaviour, Biological Responses, and Risk Implications

The environmental implications of nanoparticle-based agricultural inputs remain insufficiently understood, particularly for zinc oxide nanoparticles (ZnO-NPs), which are increasingly incorporated into fertilizers and agrochemicals. To ensure their safe and sustainable use, it is essential to evaluate both their potential phytotoxic effects and strategies to mitigate them. Magneto-priming (MP) has recently gained attention as a non-chemical, eco-friendly approach capable of enhancing seed germination, stimulating plant metabolism, and improving stress tolerance. In this study, Triticale (X Triticosecale Wittmack) seeds were subjected to two experimental approaches: (i) direct priming with ZnO-NPs at 500 and 5000 mg Zn L⁻¹, with or without MP, and (ii) exposure to soil leachates obtained from an acidic soil previously treated with the same nanoparticle concentrations. Germination percentage, shoot and root length, root number, and the Seedling Vigor Index were evaluated to assess nanoparticle-induced phytotoxicity and the potential mitigating role of MP treatment. Results showed an average 17.5 % reduction in germination in seeds directly treated with ZnO-NPs, likely due to ion release and the high reactivity of nanoparticle surfaces, indicating short-term phytotoxic potential under direct exposure. In contrast, MP treatment enhanced seedling vigour by 28.8%, improving shoot and root elongation and suggesting a capacity to alleviate early stress responses. Seeds exposed to soil leachates showed negligible effects, reflecting a limited mobility and bioavailability of ZnO-NPs within the soil matrix. These findings suggest that under the conditions of our study, soil-applied ZnO-NPs represent a low environmental risk, whereas direct contact with seeds can induce localized phytotoxic effects. In addition, MP treatment appears to modulate plant responses, enhancing root system development and mitigating nanoparticle-induced stress. Overall, the study contributes to environmental impact assessment of nanomaterials, emphasizing the need to evaluate exposure pathways and mitigation strategies for safe nano-enabled fertilizer use.