Abstract:

Water cultures were carried out to investigate the kinetic characteristics of cadmium uptake by different tobacco cultivars 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 cultivars could be described by I=Imax?C/(Km+C). The Imax of cadmium uptake followed the order of Yunyan 85>G80,Guiyan 11>Xanthi,CF965 and RG17，the Km followed the order of Xanthi> Yunyan 85> G80> Guiyan 11,RG17 and CF965,while ?, which is the ratio of Imax to Km and showed the uptake ability of mineral elements, followed the order of Guiyan 11? Yunyan 85＞CF965＞G80＞RG17＞Xanthi. Low temperature significantly decreased cadmium uptake by all tobacco cultivars 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℃. Cadmium uptake by Guiyan 11 decreased by was inhibited by 55% at solution cadmium of 0.02mmolCd?L-1, and by 34% at solution cadmium of 0.22 mmolCd?L-1 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.