Role of green synthesized nano iron oxide in alleviating the cadmium toxicity in Brassica oleracea var. italica seedlings

This work accounts for the green synthesis of iron oxide nanoparticles using Moringa oleifera leaf extract as a stabilizing and reducing agent. The preliminary confirmation of synthesized Fe₃O₄NPs was done by UV–visible spectroscopy in the wavelength range of 190–900 nm. The crystalline nature of Fe₃O₄ NPs was established via X-ray diffraction analysis. FT-IR studies reveal the bioactive phytochemicals present in the Moringa leaf extract based Fe₃O₄ NPs. A DLS particle size analyser was used to determine the size of green synthesized Fe₃O₄ NPs and its spherical morphology was determined by using SEM and TEM techniques. The growth of Brassica oleracea var. italica seedlings was measured by analysing biophysical and biochemical parameters in two concentrations of Fe₃O₄ NPs i.e. 15 mg/L and 30 mg/L alone and in combination with cadmium. Treatments were designated as control C, NP₁, NP₂, Cd+NP₁, Cd+NP_2, and Cd. Fe₃O₄ NPs treated broccoli seedlings showed noteworthy improvement in shoot length, root length, plant biomass, total chlorophyll content, carotenoid content, total soluble sugars, protein content, and nitrate reductase activity, while decline in electrolyte leakage, lipid peroxidation, proline content, superoxide dismutase activity and catalase activity was reported as compared to control. Exposure of iron oxide nano-treatments was found efficacious in reducing cadmium accumulation at a concentration of 30 mg/L. The seedlings exposed to NP₂ (30 mg/L) concentration of green synthesized nano iron oxide increased nutrient uptake and thus stimulating plant growth, and also improved morphological and physiological characteristics of Brassica oleracea seedlings. Therefore, the present study reported that bio-based iron oxide nanoparticles were significantly useful for plant growth, by enhancing the plant defense mechanism in response to cadmium induced toxicity.