土壤施锌对不同镉浓度下玉米吸收积累镉的影响

Effcet of Applied Zinc into Soil on Cadmium Uptake and Accumulation in Maize Plants under Different Cadmium Concentrations

采用盆栽试验研究了土壤施Zn量对不同Cd浓度下2种基因型玉米吉单209、长单374吸收积累Cd的影响。结果表明,土壤添加Cd浓度由6mg·kg-1增加到20mg·kg-1,2种基因型玉米地上生物量显著降低(P=0.016)。Cd6mg·kg-1处理时土壤施Zn提高了玉米生物量,Cd20mg·kg-1处理施Zn240mg·kg-1对生物量有所抑制。随添加Cd浓度的升高,2种基因型玉米植株对Cd的吸收呈线性增加。土壤施Zn降低了玉米植株中的Cd含量,2个品种玉米植株Cd含量在80或160mg·kg-1Zn时达到最低值(P<0.05)。添加Cd含量由6mg·kg-1增加到20mg·kg-1,土壤施Zn使地上部Cd含量降低幅度增加,而使根系的降低幅度减小。土壤外源Cd浓度的升高促进了2种基因型玉米地上部分的Zn含量。

To investigate effects of Zn application into soil on growth of plants and uptake of Cd and Zn under different soil Cd concentrations, a pot experiment was conducted with two genotypes of maize plants （Jidan 209 and Changdan374 used extensively in Northeast China）. Zinc fertilizers were added to soil at four levels, i.e： 0, 80, 160, 240 mg·kg^-1 soil as ZnSO4, at varied soil Cd concentrations： 6, 20 mg·kg^-1 soil. The result showed that shoot biomass of both cuhivars was decreased significantly （P=0.016） with increasing Cd concentration from 6 mg·kg^-1 to 20 mg·kg^-1 soil. Zinc application increased shoot biomass at 6 mg Cd·kg^-1 soil level. Shoot biomass of Changdan374 was generally greater than that of Jidan209 （P〈0.01）. With the increasing of added Cd concentrations from 0 to 20 mg·kg^-1 soil, the total amounts of Cd accumulated by two genotypes of maize were linearly increased （P〈0.001）. Applied Zn generally decreased Cd concentrations in two cultivars, but there were differences between in high and low Cd treatments. In Cd treatment with 6 mg·kg^-1 soil, shoot Cd concentrations reached the lowest value at 80 mg Zn·kg^-1 soil for Jidan209 and 160 mg Zn·kg^-1 soil for Changdan374, respectively（P〈0.05）. However, in treatment at 20 mg Cd·kg^-1 soil, the minima appeared at 160 mg Zn·kg^-1 soil for Jidan209 and 80 mg Zn·kg^-1 soil for Changdan374, respectively （P〈0.01）. The trend in roots was also similar. But Cd concentrations both in shoot and root were elevated by added Zn 240 mg·kg^-1 soil compared with 80 or 160 mg·kg^-1 soil due to the competitive adsorption Cd and Zn for soil colloid sites. When added Cd concentra- tions were increased from 6 to 20 mg·kg^-1 soil, decreasing degree of Cd concentrations by adding Zn was enhanced for the shoots, and reduced for the roots. It indicated that the interaction and transport of Cd and Zn in plants varied in different Cd concentrations and the mechanism needed to be elucidated further. Zn concentrations in shoots of two genotypes were elevated distinctly by increasing soil Cd concentration and no significant effects were observed for the roots.