Physiological and growth responses of wheat seedlings to green-synthesized Fe 3 O 4 and ZnO nanoparticles: an RSM-based interaction study

Although metal-based nanoparticles have potential to improve plant performance and micronutrient delivery, information on the combined effects of different nanoparticles remains limited. In this study, wormwood (Artemisia absinthium L.) extract was used for the green synthesis of ZnO and Fe3O4 nanoparticles (ZnO-NPs and Fe3O4-NPs). Their combined effects (0–1600 mg L−1) on germination, early development, physiological responses, and micronutrient accumulation in wheat (Triticum aestivum L.) were investigated using Response Surface Methodology (RSM). SEM, XRD, and FTIR analyses confirmed successful nanoparticle synthesis and phytochemical surface functionalization. The results showed that germination percentage remained relatively stable across all treatments, indicating low sensitivity of wheat seeds to nanoparticle exposure during early stages of development. In contrast, root and shoot elongation, plant height and seedling vigor index were significantly influenced by nanoparticle concentration, particularly at elevated Fe3O4-NP levels. ZnO-NPs mainly regulated chlorophyll accumulation, whereas Fe3O4-NPs showed a secondary and interaction-dependent effect. Multiple-response optimization identified the optimum condition as 0 mg L−1 Fe3O4-NPs and 1600 mg L−1 ZnO-NPs. Overall, the results demonstrated that micronutrient balance was more important than maximum nutrient accumulation and highlighted the usefulness of RSM for evaluating nanoparticle interactions and developing sustainable nano-based fertilization strategies.