New insights in to the ameliorative effects of zinc and iron oxide nanoparticles to arsenic stressed spinach (Spinacia oleracea L.)

Abstract

Nanotechnology is capturing great interest worldwide due to their stirring applications in various fields and also individual application of iron oxide nanoparticle (FeO−NPs) and zinc oxide nanoparticle (ZnO−NPs) have been studied in many literatures. However, the combined application of FeO and ZnO−NPs is a novel approach and studied in only few studies. For this purpose, a pot experiment was conducted to examine the plant growth and biomass, photosynthetic pigments, gas exchange attributes, oxidative stress and response of antioxidant compounds (enzymatic and nonenzymatic), sugars, nutritional status of the plant, organic acid exudation pattern As accumulation from the different parts of the plants in spinach (Spinacia oleracea L.) under the different As concentrations i.e., 0 (no As), 60 and 120 μM] which were primed with combined application of two levels of FeO−NPs (10 and 20 mg L−1) and ZnO−NPs (20 and 40 mg L−1). Results from the present study showed that the increasing levels of As in the soil significantly (P < 0.05) decreased plant growth and biomass, photosynthetic pigments, gas exchange attributes, sugars, and nutritional contents from the roots and shoots of the plants. In contrast, increasing levels of As in the soil significantly (P < 0.05) increased oxidative stress indicators in term of malondialdehyde, hydrogen peroxide, and electrolyte leakage, and also increased organic acid exudation patter in the roots of S. oleracea. The negative impact of As toxicity can overcome the combined application of ZnO−NPs and FeO-NPs, which ultimately increased plant growth and biomass by capturing the reactive oxygen species, and decreased oxidative stress in S. oleracea by decreasing the As contents in the roots and shoots of the plants. Research findings, therefore, suggest that the combined application of ZnO−NPs and FeO-NPs can ameliorate As toxicity in S. oleracea, resulting in improved plant growth and composition under As stress, as depicted by balanced exudation of organic acids.