Green synthesis of chitosan-stabilized iron oxide nanoparticles using Christia vespertilionis extract for sustainable nano-priming of Brassica rapa subsp. chinensis and Spinacia oleracea seeds.

Agricultural productivity worldwide is increasingly challenged by environmental stresses driven by climate change and rapid population growth. Enhancing seed germination and seedling vigor is crucial to sustaining crop productivity under such stress conditions. This study explores a sustainable nano-priming strategy using chitosan-stabilized iron oxide nanoparticles (CS-IONPs) synthesized via a green approach employing Christia vespertilionis extract. The biosynthesis provided an eco-friendly, cost-effective method, while chitosan functionalization improved nanoparticle colloidal stability and dispersion, ensuring effective interaction with seeds. Characterization confirmed the successful synthesis of stable, well-dispersed CS-IONPs. Nano-priming with CS-IONPs significantly enhanced seed germination rates, achieving 86 % in Pak Choy (Brassica rapa subsp. chinensis) and 83 % in Spinach (Spinacia oleracea), outperforming IONPs, hydropriming, and control treatments. Seedlings treated with CS-IONPs exhibited superior root (3.8 cm in Pak Choy; 3.4 cm in Spinach) and shoot (5.1 cm in Pak Choy; 4.7 cm in Spinach) growth. Physiological analyses revealed notable improvements in chlorophyll content-by 19 % in Pak Choy and 11 % in Spinach-indicating enhanced photosynthetic efficiency. Antioxidant activity was also elevated by 14 % compared to controls, suggesting improved stress resilience. These findings demonstrate the potential of CS-IONPs as an eco-friendly, biocompatible nano-priming agent that can boost seedling establishment and promote sustainable agriculture. Future work, including field trials and long-term environmental impact assessments, will be crucial to fully realize the potential of this innovative approach in large-scale farming systems.