Nano-FeO as a tool to restore plant growth in contaminated soils - Assessment of potentially toxic elements (bio)availability and redox homeostasis in Hordeum vulgare L.

This work aimed to evaluate the potential of FeO nanoparticles (nano-FeO) to alleviate potentially toxic elements (PTEs) - induced stress in barley plants (Hordeum vulgare L.), focusing on bioaccumulation patterns and on plant growth and redox homeostasis. To achieve this goal, plants grew in two agricultural soils, contaminated by different levels of PTEs, collected from an industrial area, previously amended, or not, with 1% (w/w) nano-FeO. After 14 d of growth, biometric parameters were evaluated, along with the analysis of PTEs bioaccumulation and biochemical endpoints. After exposure to contaminated soils, plant development was greatly affected, as evidenced by significant decreases in root length and biomass production. However, upon co-treatment with nano-FeO, lower inhibitory effects on biometric parameters were observed. Regarding the oxidative damage, both soils led to increases in lipid peroxidation and superoxide anion concentration, though hydrogen peroxide levels were only increased in the most contaminated soil. In general, these changes in the oxidative stress markers were accompanied by an upregulation of different antioxidant mechanisms, whose efficiency was even more powerful upon soil amendment with nano-FeO, thus lowering PTEs-induced oxidative damage. Altogether, the present study revealed that nano-FeO can protect the growth of barley plants under contaminated soils.