Spraying Cerium Oxide Nanoparticles to Optimize Morphological Structure and Physiological Response of Fragrant Rice Seedlings Under Cadmium Stress

Fragrant rice is highly valued for its unique aroma but is vulnerable to heavy metal stress, particularly cadmium (Cd). This study investigates the effects of cerium oxide nanoparticles (CeO₂-NPs) on growth, photosynthetic properties, antioxidant enzyme activities, and aroma synthesis in fragrant rice seedlings under Cd stress. Heavy metal contamination in agriculture, particularly cadmium, is exacerbated by its high mobility. Nanotechnology, particularly the application of cerium oxide nanoparticles (CeO₂-NPs), presents a significant yet underexplored potential for mitigating these detrimental effects. Our results demonstrate that CeO₂-NPs significantly enhance the tolerance of fragrant rice seedlings to Cd stress. This is achieved primarily by reducing Cd uptake and suppressing the expression of genes responsible for Cd uptake and translocation. CeO₂-NPs also improve the antioxidant capacity of the seedlings, alleviate the impairment of the photosynthetic system under Cd stress, and promote root and overall plant growth. Additionally, CeO₂-NPs increase the aroma content of fragrant rice by enhancing the activity of aroma-related enzymes, increasing proline content, and subsequently elevating the levels of 2-acetyl-1-pyrroline (2-AP), a key aromatic compound. The study underscores the dual role of CeO₂-NPs in mitigating Cd toxicity and enhancing aromatic quality in fragrant rice. These findings suggest that CeO₂-NPs are a promising tool for protecting and improving the quality of fragrant rice in Cd-contaminated environments, offering a potential strategy for managing heavy metal stress in agriculture.