铜污染对玉米幼苗的毒性及其机制研究

用不同质量浓度的Cu处理玉米幼苗，分析了Cu毒性对幼苗生长的影响和体内氧化损伤情况，并采用分步提取技术研究了玉米幼苗地上部分中Cu的化学形态分布。结果表明加Cu处理明显抑制了玉米的生长和发育，并引起肉眼可见的伤害。铜胁迫导致玉米幼苗叶片中抗氧化酶系统中酶活性的变化，在本研究的Cu处理质量浓度范围（5~160mg/L）内，随着Cu质量浓度的增加，幼苗叶片中的超氧化物歧化酶(SOD)、过氧化物酶(POD)活性升高，过氧化氢酶(CAT)活性先升高后下降。铜胁迫还会导致植物体内的氧化损伤，丙二醛含量随Cu处理质量浓度提高而增加。玉米幼苗累积的Cu在体内以不同的化学形态分布，通过体内结合机制降低体内Cu的移动性是玉米幼苗抵抗Cu污染危害的重要机制之一。

Toxicity of copper to maize seedlings and its mechanism of action

Hydroponics experiments were used to investigate the toxic effects of copper(Ⅱ) on maize seedlings and the mechanism responsible. When treated with different concentrations of copper(Ⅱ), the growth and the oxidative damage of maize seedlings was monitored and a sequential extraction technique was used to study the distribution of chemical forms of Cu²⁺ in the shoots of maize seedlings. The results showed that the growth inhibition of maize seedlings increased with increasing Cu²⁺ concentration and the presence of Cu²⁺ led to macroscopic scars. Copper(Ⅱ)induced stress leads to changes in enzyme activity in the antioxidant enzyme system of maize seedling blades. In the mass concentration range of Cu²⁺ employed (5-160mg/L), the activities of superoxide dismutase (SOD) and peroxidase (POD) increased and the activity of catalase (CAT) initially increased and then decreased with increasing Cu²⁺ concentration. Copper(Ⅱ) also results in oxidative damage in the plants, and the content of malondialdehyde increased with increasing concentration of Cu²⁺. The Cu²⁺ accumulated in maize seedlings in different chemical forms, and one of the main mechanisms to resist Cu²⁺ pollution is by decreasing the mobility of Cu²⁺ in plants by means of the binding mechanism.