Plants are frequently exposed to various abiotic stresses, including drought, salinity, and heavy metal toxicity, all of which significantly limit crop productivity and threaten global food security ([11]; A. [29]). Among these stresses, heavy metal contamination, particularly cadmium (Cd), has become a major environmental concern due to its toxicity, persistence, and widespread occurrence in agricultural soils [3], [56]. Cd contamination primarily arises from industrial discharges, mining operations, sewage sludge applications, and excessive use of phosphate fertilizers, all of which contribute to Cd accumulation in agroecological zones [6], [55]. In Pakistan, phosphate fertilizers may contain Cd concentrations ranging from 3 to 155 mg/kg, resulting in soil Cd levels between 0.1 and 1.5 mg/kg, while industrial effluents from cities like Rawalpindi, Lahore, and Karachi contribute up to 2.5 mg/kg to nearby soils [45]. Cd exposure severely disrupts key plant physiological processes, including nutrient uptake, photosynthesis, and stomatal conductance, ultimately leading to chlorosis, root stunting, leaf necrosis, reduced biomass, and lower grain yields [17], [45]. Furthermore, Cd toxicity negatively impacts plant metabolism, causing oxidative stress due to the overproduction of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), hydroxyl radicals (•OH), and superoxide radicals (O2•−), which damage cellular components including nucleic acids, lipids, and proteins [16], [28]. To counteract oxidative damage, plants activate antioxidant defense mechanisms, involving enzymatic antioxidants like superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), as well as non-enzymatic antioxidants such as ascorbic acid, glutathione, and tocopherols [37], [65].

Wheat (Triticum aestivum L.), a globally important staple crop, is highly susceptible to Cd stress, which not only reduces productivity but also poses severe risks to food safety and human health due to Cd accumulation in edible grains [31]. Wheat is cultivated in diverse soil types and climatic conditions, providing essential proteins, starches, and dietary fibers. However, Cd contamination in agricultural soils, originating from phosphate fertilizers, industrial effluents, and mining activities, disrupts essential physiological pathways in wheat, leading to nutrient imbalances, impaired photosynthesis, stunted growth, and reduced grain yields [46], [63]. Elevated Cd levels in edible plant parts further pose significant health risks, making it imperative to develop effective mitigation strategies [4], [56]. To mitigate Cd-induced damage, various remediation techniques have been explored, including soil amendments, phytoextraction, phytostabilization, and bioremediation [39], [66].

Nanotechnology has emerged as a promising approach for enhancing plant growth and tolearnace against biotic and abiotic stresses [42], [36]. Notably, selenium nanoparticles (Se-NPs) have gained significant attention for their ability to enhance antioxidant defense systems, improve nutrient uptake, and protect photosynthetic machinery, thereby mitigating Cd-induced oxidative stress [43], [8]. Se-NPs modulate plant physiological and biochemical pathways, reducing oxidative damage and promoting growth under Cd-contaminated conditions, offering a sustainable strategy for improving wheat productivity in heavy metal-stressed soils ([40]b) [23]. Studies have shown that Se-NPs enhance Cd stress tolerance in crops such as wheat, rice, maize, and tomatoes by boosting antioxidant activity and improving overall plant performance [12], [26]. Given the rising concerns over Cd contamination in agricultural soils and its detrimental effects on wheat productivity and food safety, it is crucial to explore innovative and sustainable approaches for mitigating Cd stress. The application of Se-NPs presents a promising solution to enhance plant resilience, reduce Cd accumulation, and ensure sustainable agricultural production. This study aims to investigate the role of Se-NPs in alleviating Cd-induced toxicity in wheat, focusing on their impact on physiological, biochemical, and antioxidative responses to promote plant health and yield stability under Cd stress conditions. We hypothesize that Se-NPs could effectively alleviate Cd stress in wheat. This study involves the green synthesis of Se-NPs and their application to the high-yielding wheat cultivar Pak-13 to assess Cd stress alleviation. Agronomic, antioxidant, and nutritional profiling were conducted to understand Cd mitigation in crops. Unlike previous studies focused on model plants or hydroponic systems, this research evaluates biosynthesized Se-NPs under realistic soil conditions, providing novel insights into their role in enhancing wheat tolerance and improving grain quality in Cd-contaminated soils.