Responses of maize germination,root morphology and leaf trait to characteristics of lead pollution:a case study

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 mm^(2),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.

Characteristics of heavy metals in soil of lead-zinc mining areas and changes of antioxidant enzyme systems in maize leaf under Pb stress

Pb,Cu,Cd,Zn content of soil in mining areas and abandoned land,flats of the Pijiang River and farmlands were inves-tigated.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 concentra-tion,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.