Pb, Cu, Cd, Zn content of soil in mining areas and abandoned land, flats of the Pijiang River and farmlands were investigated. On this basis of soil heavy metal pollution, the changes of antioxidant enzyme system in maize (Qiandan 88) under different Pb concentrations (0, 20, 40, 60, 80, 100, 150, 200, 500, 1000, 2000, 3000 mg/L) stress were studied. The results show that the content of Pb, Cu, Cd, and Zn in soil is the highest in mining areas and abandoned land, followed by flats of the Pijiang River > farmlands, and that the variation range of Pb, Cu, Cd in mining areas and abandoned land are 106.40–2564.72, 14.83–490.88, 22.57–712.77 mg/kg, respectively, which are higher than that of the other land use types. When maize is under stress of 20–500 mg/L Pb concentration, T-SOD activity of maize leaves increase with the increase of Pb concentration and the highest value is 50.21 U/mg prot, but under Pb concentration > 1000 mg/L stress, T-SOD activity of maize leaves decrease gradually. The activity of POD decreases with the increases of Pb concentration, and the lowest POD activity of leaves in maize with the value of 93.24 U/mg prot is appeared in Pb 1000 mg/L concentration treatment group. MDA content in leaves of maize increases with the increase of the Pb concentration and the highest value is 101.98 nmol/mg prot, then the content of MDA decreases gradually when the Pb concentration is more than 500 mg/L, which indicates that the membrane lipid peroxidation of maize leaves under high concentration of Pb stress is serious and leads to the cell damage.

On base of the content of Pb in the soil under different land use patterns in Lanping Lead-zinc mining area, Yunnan in southwest China, the root morphology and leaf traits of maize in different concentration Pb (20, 40, 60, 80, 100, 150, 200, 500, 1000, 2000, 3000 mg/L) were analyzed. The results showed that maize germination rate, germination vigor and growth index decreased with the increase of Pb concentration. The root length, surface area of maize increased by 0.21%–81.58%, 8.99%–73.43%, 1.50%–77.37%, respectively, under 20–500 mg/L Pb concentration. However, these parameters under 1000–3000 mg/L Pb concentration decreased by 37.86%–553.54%, 44.99%–766.16%, 55.99%–92.81%, respectively, and these lowest value appeared in 3000 mg/L Pb treatment. The root volume of maize increased by 4.57%–89.25% in 20–80 mg/L Pb concentration, and it decreased with the increase of Pb concentration when the Pb concentration was higher than 80 mg/L and decreased by 94.13% in 3000 mg/L Pb. The root surface area and length of 0.50–1.00 diameter class were higher than those of other diameter classes, and these value of maize under 500 mg/L Pb were higher than those of other concentrations. The length and perimeter of maize leaves with the highest value of 220.36 and 962.68 mm, respectively appeared in 60 mg/L Pb treatment. The leaf width and area of maize with the highest value of 15.68 mm and 2448.31 mm2, respectively, appeared in 40 mg/L Pb treatment, which indicated that the leaf traits of maize were promoted by low concentration Pb and inhibited by high concentration Pb.

Reducing the bioavailability of Pb in soil is the key to alleviate the toxicity of Pb to plant. Maize were exposed to Pb 100 mg/kg of soil with three fertilizer levels of control (T1), nitrogen, phosphorus and potassium of 204 mg/kg (T2) and nitrogen, potassium of 204 mg/kg (T3). The phosphate supplement lead to the reduction by 24.92%, 29.73% and 25.31% respectively in activity of total superoxide dismutase (T-SOD), peroxidase (POD) and concentration of lipid peroxidation (MDA) in maize leaves, and reduced Pb accumulation in above- and below-ground biomass of maize by 39.20% and 37.58%. In T2 treatment group, the water soluble Pb, ionic fraction and carbonate fraction Pb in rhizosphere soil decreased by 37.57%, 36.36% and 43.24%, and organic fraction Pb and residual fraction Pb was the highest with the value of 11.67 and 18.57 mg/kg; the soil aluminum bound (Al-P) and iron bound phosphate (Fe-P) were the highest with 93.53 mg/kg and 230.32 mg/kg, indicating that the phosphate supplement increases the soil ionic P and transforms the chemically mobilized P (such as O-P, Ca-P) into the bioavailable P. Moreover, the soil organic fraction and residual fraction immobilized Pb was positively correlated with the bioavailable Al-P and Fe-P, indicating that the ionic fraction P (Al-P and Fe-P) react with Pb and produce residual P-Pb compounds. Therefore, phosphate supplement to Pb contaminated soil could transfer unstable fraction Pb into stable fraction Pb by P-induced Pb immobilization, reduce the bioavailability of Pb and alleviate the toxicity of heavy metal to plant.