In this study, the effects of different concentrations (0, 200, 400, 800, and 1600 mg/kg) of bare and chitosan(CS)-coated Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) on seed germination and seedling growth of sweet pepper (Capsicum annuum L.) were evaluated. Bare and CS-Fe3O4MNPs in the size range of 3-22 nm were synthesized by co-precipitation and polyelectrolyte complex (PEC) procedures, respectively. Consequently, they were characterized using FT-IR, XRD, VSM, SEM, TEM and DLS techniques. Then, the effects of the prepared nanomaterials were evaluated on physiological parameters such as germination rate and speed, rootlet and shootlet length, fresh and dried weights as well as total iron content. It was found that bare and CS-Fe3O4 MNPs with concentrations of 200 and 400 mg/kg had significant impacts on seed germination and seedling growth. In addition, the higher concentrations of MNPs showed toxic effects. Taken all together, CS-Fe3O4 MNPs had better efficiency on the evaluated parameters in comparison to bare Fe3O4 MNPs
