Foliar-Applied Selenium Nanoparticles Can Alleviate Soil-Cadmium Stress Through Physio-chemical and Stomatal Changes to Optimize Yield, Antioxidant Capacity, and Fatty Acid Profile of Wheat (Triticum aestivum L.)

Around the world, large areas of agricultural soils are contaminated by cadmium (Cd), and for safe food production, there is a need for cost-effective and practical methods to manage this contamination. The goal of this study was to investigate the effects of selenium nanoparticles (Se-NPs) on physiological and biochemical attributes of wheat (Triticum aestivum L.) in Cd-contaminated soils. A pot experiment was carried out with different Cd concentrations (0, 10, and 20 mg Cd kg−1 soil) and foliar application of Se-NPs (0, 20, and 40 mg L−1) with respect to measurement of yield, water content, proline concentration, antioxidant enzyme activity, stomatal properties, and fatty acid (FA) profile. The results showed enhanced Cd amount in roots, shoots and grains of wheat under Cd stress; however, Se-NPs alleviated the uptake of Cd by roots. The Cd stress decreased grain yield (GY), thousand grain weight (TGW), and relative water content (RWC), but these negative effects could be reduced by application of Se-NPs. Proline concentration as well as superoxide dismutase (SOD) and catalase (CAT) activities increased compared to the control in plants exposed to Cd-contaminated soil. When experiencing severe Cd stress, plants responded with increase of stomatal density and reduction of stomatal length. However, Se-NPs had no significant effect on stomatal size and density. Increased polyunsaturated fatty acid (PUFA) and decreased saturated fatty acid (SFA) were observed by progressing Cd stress. Twenty to 40 mg L−1 Se-NPs can be recommended to mitigate soil Cd stress in wheat plants.