Cerium Improves Growth of Maize Seedlings via Alleviating Morphological Structure and Oxidative Damages of Leaf under Different Stresses

It had been indicated that cerium (Ce) could promote maize growth involving photosynthetic improvement under potassium (K) deficiency, salt stress, and combined stress of K⁺ deficiency and salt stress. However, whether the improved growth is related to leaf morphological structure, oxidative stress in maize leaves is not well understood. The present study showed that K⁺ deficiency, salt stress, and their combined stress inhibited growth of maize seedlings, affecting the formation of appendages of leaf epidermal cells, and stomatal opening, which may be due to increases in H₂O₂ and malondialdehyde levels, and reductions in Ca²⁺ content, ratios of glutathione/oxidized glutathione, ascorbic acid/dehydroascorbic acid, and the activities of superoxide dismutase, catalase, ascorbic acid peroxidase, guaiacol peroxidase, and glutathione reductase in leaves under different stresses. The adverse effects caused by combined stress were higher than those of single stress. Furthermore, our findings demonstrated that adding Ce³⁺ could significantly promote seedling growth, and alleviate morphological and structural damage of leaf, decrease oxidative stress and increase antioxidative capacity in maize leaves caused by different stresses.