Xu Lina, Xue Xing, Yan Yan, Zhao Xiaotong, Li Lijie, Sheng Kun, Zhang Zhiyong
College of Agriculture, Henan Institute of Science and Technology, Xinxiang 453003, China.
School of Hydraulic Engineering, Yellow River Conservancy Technical Institute, Kaifeng 475004, China.
Plants (Basel). 2023 Oct 11;12(20):3537. doi: 10.3390/plants12203537.
Cadmium (Cd) is one of the most toxic and widely distributed heavy metal pollutants, posing a huge threat to crop production, food security, and human health. Corn is an important food source and feed crop. Corn growth is subject to Cd stress; thus, reducing cadmium stress, absorption, and transportation is of great significance for achieving high yields, a high efficiency, and sustainable and safe corn production. The use of silicon or melatonin alone can reduce cadmium accumulation and toxicity in plants, but it is unclear whether the combination of silicon and melatonin can further reduce the damage caused by cadmium. Therefore, pot experiments were conducted to study the effects of melatonin and silicon on maize growth and cadmium accumulation. The results showed that cadmium stress significantly inhibited the growth of maize, disrupted its physiological processes, and led to cadmium accumulation in plants. Compared to the single treatment of silicon or melatonin, the combined application of melatonin and silicon significantly alleviated the inhibition of the growth of maize seedlings caused by cadmium stress. This was demonstrated by the increased plant heights, stem diameters, and characteristic root parameters and the bioaccumulation in maize seedlings. Under cadmium stress, the combined application of silicon and melatonin increased the plant height and stem diameter by 17.03% and 59.33%, respectively, and increased the total leaf area by 43.98%. The promotion of corn growth is related to the reduced oxidative damage under cadmium stress, manifested in decreases in the malondialdehyde content and relative conductivity and increases in antioxidant enzyme superoxide dismutase and guaiacol peroxidase activities, as well as in soluble protein and chlorophyll contents. In addition, cadmium accumulation in different parts of maize seedlings and the health risk index of cadmium were significantly reduced, reaching 48.44% (leaves), 19.15% (roots), and 20.86% (health risk index), respectively. Therefore, melatonin and silicon have a significant synergistic effect in inhibiting cadmium absorption and reducing the adverse effects of cadmium toxicity.
镉（Cd）是毒性最强、分布最广的重金属污染物之一，对作物生产、粮食安全和人类健康构成巨大威胁。玉米是重要的食物来源和饲料作物。玉米生长易受镉胁迫影响；因此，减轻镉胁迫、吸收和转运对于实现玉米高产、高效以及可持续安全生产具有重要意义。单独使用硅或褪黑素可减少植物体内镉的积累及其毒性，但硅和褪黑素联合使用是否能进一步减轻镉造成的损害尚不清楚。因此，开展盆栽试验研究褪黑素和硅对玉米生长及镉积累的影响。结果表明，镉胁迫显著抑制玉米生长，扰乱其生理过程，并导致植物体内镉积累。与单独施用硅或褪黑素相比，褪黑素和硅联合施用显著缓解了镉胁迫对玉米幼苗生长的抑制。这体现在玉米幼苗株高、茎粗和特征根参数增加以及生物积累量增加。在镉胁迫下，硅和褪黑素联合施用使株高和茎粗分别增加了17.03%和59.33%，总叶面积增加了43.98%。玉米生长的促进与镉胁迫下氧化损伤减轻有关，表现为丙二醛含量和相对电导率降低，抗氧化酶超氧化物歧化酶和愈创木酚过氧化物酶活性增加，以及可溶性蛋白和叶绿素含量增加。此外，玉米幼苗不同部位的镉积累量和镉的健康风险指数显著降低，分别达到48.44%（叶片）、19.15%（根系）和20.86%（健康风险指数）。因此，褪黑素和硅在抑制镉吸收及减轻镉毒性的不利影响方面具有显著的协同效应。
