Seed Priming with Iron Oxide Nanoparticles Modulate Antioxidant Potential and Defense Linked Hormones in Watermelon Seedlings

In the present study, onion extract was used for green synthesis of iron oxide nanoparticles (Fe-NPs). The X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy characterizations demonstrated that the biosynthesized Fe-NPs were mainly of low-crystalline or amorphous Fe2O3 with diameter of 19-30 nm. The effect of seed priming with different concentrations of Fe-NPs (20, 40, 80, and 160 mg L-1) on seedling growth parameters, photosynthetic pigments, antioxidant potential, metabolites and hormonal profiles of diploid and triploid watermelon (Citrullus lanatus (Thunb.) Matsum. u0026 Nakai) varieties were further studied on 3rd and 8th days of seedling development. Seed priming with Fe-NPs was safer compared to its bulk counterparts (FeCl3 and Fe2O3), and had no toxic impact on seed germination, seedling development, and chlorophyll biosynthesis at studied concentrations. Untargeted metabolomics studies showed that different Fe-NPs priming treatments distinctly a...