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- 160 mg / 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.