Nano-priming is an efcient process that can alter seed germination metabolism and signaling pathways, afecting seedling establishment and entire plant life cycle. This study was aimed to investigate the efect of diferent concentrations of titanium dioxide (TiO2) and silicon dioxide (SiO2) nanoparticles (NPs) on germination indices and biochemical traits of marigold and lemon balm seedlings in a split plot experiment based on completely randomized design with three replications (n=3). The main plot treatments consisted of two plant species, and sub-plot treatments include diferent concentrations of TiO2 and SiO2 NPs (0, 250, 500 and 1000 mg/L). Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses confrmed the uptake of TiO2 and SiO2 NPs through root surface of tested seedlings. Results showed that the two plant species were diferentially afected in terms of root and shoot length, vigor index, electrolyte leakage, malondialdehyde content, hydrogen peroxide level, proline, protein and total phenol contents and alpha-amylase activity. The observed results are found to be dose-and species-dependent, with lower concentration being optimum for seed germination features. Such studies could prove the signifcant potential of TiO2 and SiO2 NPs as regulators of germination and seedling growth
