不同品种烟草镉吸收的动力学研究

Kinetic Characteristics of Cadmium Uptake by Different Tobacco Cultivars

通过水培试验研究了不同品种烟草幼苗镉吸收的动力学特征及温度、代谢抑制剂对烟草镉吸收的影响。结果表明,烟草对镉的吸收Michaelis-Menten动力学方程I=Imax·C/(Km+C)描述,不同品种间吸收的最大速率(Imax)为云烟85>G80、贵烟11号>Xanthi、CF965和RG17,Km为Xanthi>云烟85>G80>贵烟11号、RG17和CF965,a(Imax/Km,根系对矿质元素的吸收能力)为贵烟11号≈云烟85>CF965>G80>RG17>Xanthi。低温使各品种烟草镉的吸收量明显降低,代谢抑制使G80,Xanthi和CF965镉的吸收量降低50%以上,使RG17和云烟85镉的吸收量降低24%~44%,使贵烟11号镉的吸收量在营养液镉浓度为0.02mmol/L时降低55%,营养液镉浓度为0.22mmol/L时降低34%。表明G80,Xanthi和CF965对镉的吸收以主动吸收过程为主,RG17和云烟85对镉的吸收以被动吸收过程为主,而贵烟11号镉的吸收在低镉浓度时以主动吸收过程为主,在较高镉浓度时以被动吸收过程为主。

Water cultures were carried out to investigate the kinetic characteristics of cadmium uptake by different tobacco euhivars and the effects of low temperature and metabolic inhibitor on cadmium uptake by tobacco seedlings. The results showed that the kinetic characteristics of cadmium uptake by different tobacco cuhivars could be described by I=I~. C/（Km＋ C）. The Ira, of cadmium uptake followed the order of Yunyan 85〉 G80,Guiyan 11〉Xanthi,CF965 and RG17, the K^followed the order of Xanthi〉 Yunyan 85〉 GS0〉 Guiyan 11, RG17 and CF965,while a, which is the ratio of In to Km and showed the uptake ability of mineral elements, followed the order of Guiyan 11 ~ Yunyan 85 〉 CF965 〉 G80 〉 RG 17 〉 Xanthi. Low temperature significantly decreased cadmium uptake by all tobacco cuhivars tested. Cadmium uptake decreased by more than 50% for G80, Xanthi and CF965, respectively, and decreased by 24%-44% for RG17 and Yunyan 85 at 2~C. Cadmium uptake by Guiyan 11 decreased by was inhibited by 55% at solution cadmium of 0.02mmolCd/L, and by 34% at solution cadmium of 0.22 mmolCd/L when the metabolic inhibitor, 2,4-DNP, was supplied in the solution. The results implied that the active absorption dominated the process of cadmium uptake by G80, Xanthi and CF965, while passive absorption dominated in the process of cadmium uptake by the tobacco cultivars RG17 and Yunyan 85. For Guiyan 11, the cadmium uptake was dominated by the active absorption process at low cadmium concentration in solution, while as dominated by the passive absorption process at high cadmium concentration in solution.