Synergistic effects of glutamic acid and cerium oxide nanoparticles on cadmium phytoremediation efficiency in marigold
摘要
The presence of heavy metals in soil, water, and air is an emerging critical environmental challenge due to their non-biodegradability and toxicity. Therefore, this study was designed to evaluate the phytoremediation of cadmium (Cd) using the combined effect of glutamic acid (GA, 10 mM) and cerium oxide nanoparticles (CeO₂NPs, 150 mgL− 1) in marigold. Over 28 days in a completely randomized design experiment, the effects of CeO₂ NPs and GA on plant growth, photosynthetic pigments, antioxidant enzymes, reactive oxygen species (ROS), electrolyte leakage (EL), SPAD values, soluble proteins, and Cd accumulation in marigold plants were assessed. Exposure to Cd, especially at 5.0 mM, significantly reduces plant growth, chlorophyll content, and protein levels while increasing ROS, EL, and oxidative damage. However, the combined application of GA and CeO₂NPs alleviated Cd toxicity by improving growth parameters, enhancing chlorophyll and protein content, and boosting antioxidant defenses. Notably, the applied treatment also increased Cd accumulation in roots (108%), stems (106%), and leaves (119%) relative to controls. SPAD values and soluble protein levels increased under the combined treatment, thereby improving photosynthetic efficiency and metabolic resilience. The results also showed a substantial reduction in oxidative stress markers such as hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), confirming a strong protective effect. These findings reveal that GA and CeO₂NPs can enhance both Cd tolerance and uptake in marigold, suggesting potential for improving phytoremediation efficiency under controlled conditions.