Iron (III) oxide nanoparticles alleviate arsenic induced stunting in Vigna radiata.

Iron nanoparticles (NPs) are widely used for the removal of arsenic from water. In this study, we evaluated the interaction between arsenate (AsO) and FeO-NPs on early seedling growth of Vigna radiata. Seedlings were raised in AsO and FeO-NPs, alone and in combination. While FeO-NPs slightly promoted seedling growth, AsO reduced seedling growth drastically. AsO-induced decline in the seedling growth was recovered by FeO-NPs. In contrast, equivalent concentrations of FeCl, alone and together with AsO, inhibited seed germination completely. Lower arsenic content in seedlings raised in the presence of FeO-NPs indicated that FeO-NPs restricted arsenic uptake. Ability of FeO-NPs to restrict the arsenic uptake of the seedlings was due to adsorption of AsO, as revealed by transmission and scanning electron microscopy. Non-toxic levels of iron in seedlings were due to restriction of FeO-NPs to root-surface. AsO enhanced the ferric chelate reductase activity of root which was recovered by FeO-NPs. The AsO-induced oxidative stress, evident from high levels of proline, HO and malondialdehyde, and lowered root oxidisability was ameliorated by FeO-NPs. AsO-induced enhancement in total antioxidant capacity, superoxide dismutase and catalase activity, and decline in guaiacol peroxidase activity were antagonized by FeO-NPs. Our findings reveal that FeO-NPs provide effective resistance/amelioration to arsenic toxicity by reducing arsenic availability to plants.