Effect of Fe₃O₄ nanoparticles on seed germination in tobacco

Many studies on the toxicity of nanoparticles (NPs) have reported different levels of toxicity for various types of NPs. This study aimed to examine the morpho-ultrastructural impact of iron oxide (Fe₃O₄) NPs on seed germination in tobacco (Nicotiana tabacum var. Turkish) using different sizes and concentrations of nanoparticles. Seeds were allowed to germinate in the presence of (Fe₃O₄) NPs of three different sizes (5, 10, and 20 nm) at three different concentrations 3, 10, and 30 mg/L for each size. Seeds were assessed using light and transmission microscopy. Radical lengths and seed germination rate were significantly affected (positively or negatively) in all NPs-treated seeds compared to control seeds. The radical lengths in 5 nm-treated seeds (30 mg/L concentration) and 10 nm-treated seeds (10 and 30 mg/L concentrations) were significantly shorter than control seeds. In contrast, the radical lengths in 10 nm-treated seeds (3 mg/L concentration) and 20 nm-treated seeds (10 mg/L concentration) were significantly longer than control seeds. Most NPs-treated seeds exhibited significant higher seed germination except for seeds treated with 5 nm NPs (3 mg/L concentration). Moreover, thick and thin micrographs of radicles and leaflets of 5 nm NPs-treated seeds (30 mg/L concentration) and 10 nm NPs (30 mg/L concentration) showed structural and ultrastructural deformation. Thus, these findings confirm that the toxicity and the bioaccumulation of (Fe₃O₄) NPs were size and concentration dependent.