Can Fe2O3 nanomaterials improve crop tolerance to contaminated soils?

Resumo

As a result of anthropic pressures, soil contamination is increasing and, consequently, compromising soil functions and impacting crop yields worldwide. Among all contaminants, potentially toxic elements (PTEs) are some of the most common and important, being able to negatively affect the growth and development of plants. Nanotechnology, an emerging field in technological sciences, offers multiple tools that can be used for this purpose. In this way, this work aimed to evaluate the potential of Fe2O3 nanomaterials (nano-Fe2O3) to alleviate metalinduced stress in barley plants (Hordeum vulgare L.), focusing on bioaccumulation patterns and on the redox homeostasis. To achieve this goal, plants grew under two agricultural soils, contaminated with different levels of PTEs, collected from an industrial area, and previously treated or not, with 1% (w/w) nano-Fe2O3. After 14 days of growth, biometric parameters, PTE bioaccumulation and biochemical endpoints, especially those related to the induction of redox disorders, were evaluated. The effectiveness of nano-Fe2O3 to reduce available PTEs in soil solution was also assessed. After exposure to contaminated soils, plant development was greatly affected, as evidenced by significant decreases in root length and fresh weight of roots and leaves. However, upon co-treatment with nano-Fe2O3 this phytotoxicity was partially recovered, with less inhibitory effects on biometric parameters, especially on the less contaminated soil. This pattern was also noticed for levels of total chlorophylls and carotenoids. Regarding the oxidative damage, both soils led to increases in Lipid Peroxidation (LP), though H2O2 levels were only increased in the most contaminated soil. In response to the co-treatment with nano- Fe2O3, barley plants exhibited less oxidative damage, which is evidenced by the decrease of H2O2 and LP in both soils. The present study revealed that nano-Fe2O3 can enhance the tolerance of barley plants to contaminated soils, possibly by limiting the occurrence of oxidative stress, through a set of modifications in the PTE (bio)availability.