Enhancing cadmium stress tolerance in mungbean through foliar application of selenium nanoparticles by modulating photosynthetic efficiency and antioxidative mechanisms

Cadmium (Cd) contamination has become a major environmental issue and has toxic effects on agricultural crops. Selenium (Se) is an essential trace element that plays an important role due to its impact on several physiological and biochemical processes in plants. This study addresses the mechanistic insights into the role of SeNPs in enhancing Cd stress tolerance, thereby contributing to sustainable nano-agronomic strategies for the soils contaminated with heavy metals (HMs). The current experimental approach involved a pot trial conducted in a greenhouse with two levels of cadmium stress (C₁ = control; C₂ = 20 mg kg^-1 of soil w/w using CdCl₂), and four levels of SeNPs (0, 25, 50, and 75 mg L^-1) in mungbean plants. The findings indicated that cd stressed conditions significantly affected the productivity of mungbean plants. The optimal level of SeNPs significantly enhanced the growth, biomass, and photosynthetic traits of mungbean. This study also indicated that Cd-stressed conditions increased lipid peroxidation and membrane damage. Moreover, SeNPs application increased soluble protein (110.10%), and decreased the proline accumulation (64.45%) and malondialdehyde (MDA) contents (64.25%) in comparison with control (0 mg L^-1 of SeNPs). Furthermore, the SeNPs also decreased the leaf Cd contents by 64.95% and grain Cd contents by 64.88% by reduced Cd uptake. An optimum level of SeNPs offers great potential as an eco-friendly and feasible method for mitigating the effects of Cd stress on mungbean plants. However, long-term environmental impact of Se NPs, including their bioavailability, accumulation, and potential toxicity, is crucial for ensuring their safe and sustainable use in agriculture.