Supplementary file 1_Cerium-coated Fe3O4 nanocomposite enhances salt stress tolerance in maize by modulating photosynthetic efficiency, antioxidant defense, and cellular ultrastructure.docx

IntroductionSoil salinity, characterized by excessive soluble salts in the root zone, affects over 950 million hectares globally and continues to expand due to climate change, seawater intrusion, and unsustainable agricultural practices. High salinity imposes osmotic and ionic stress on plants, disrupting water and nutrient uptake, inducing ion imbalance, and triggering excessive reactive oxygen species (ROS) production, which leads to oxidative damage and impaired plant growth. Nanotechnology is an emerging strategy for enhancing plant stress tolerance, and combining nanomaterials with complementary properties offers a promising approach to improve plant resilience under such conditions.
MethodsThis study evaluated the efficacy of cerium-coated triiron tetraoxide (Fe3O4@Ce) nanocomposites (NCs) applied at different concentrations to mitigate salt stress in maize. Seedlings were subjected to 150 mM NaCl and treated with foliar-applied NCs. Growth parameters, photosynthesis, oxidative stress markers, ion homeostasis, and ultrastructural changes were analyzed.
Results and DiscussionSalt stress significantly reduced plant growth, biomass, and photosynthetic efficiency while increasing oxidative damage and disrupting cellular ultrastructure. In contrast, NC application enhanced biomass production, chlorophyll content, antioxidant enzyme activities, and osmolyte accumulation, while reducing malondialdehyde (MDA), superoxide (O2•⁻), and hydrogen peroxide (H2O2) levels. The treatment decreased Na+ accumulation and increased K, Ca, and Mg uptake, improving ionic homeostasis and alleviating oxidative stress. Gas exchange parameters and stomatal structure were restored, and ultrastructural analyses confirmed recovery of mesophyll and root cell integrity. These results indicate that Fe3O4@Ce nanocomposites mitigate salt stress through coordinated regulation of antioxidant defense, ion balance, and cellular structure, highlighting their potential as an eco-friendly strategy for enhancing crop resilience.