Tolerance and accumulation of zinc and cadmium in two ecotypes of Thlaspi caerulescens

摘要

The tolerance and accumulation of Zn and Cd were investigated in two ecotypes of Thlaspi caerulesces, Ganges and Prayon. Seedlings were exposed to a nutrient solution containing 10 mu M Zn in the presence of 0,10, 50, 200 mu M Cd for 17 days. The shoot growth was inhibited by 33% and 15% by 200 mu M Cd, respectively, in Ganges and Prayon, suggesting that Prayon ecotype has slightly higher tolerance to Cd than Ganges ecotype. Cd accumulation in both roots and shoots of the two ecotypes increased withincreasing Cd concentration in the external solution. However, the Ganges ecotype accumulated much more Cd in both roots and shoots than Prayon did at either Cd concentration. Zn accumulation in Ganges was much higher than Prayon in the absence of Cd. The Zn accumulation was significantly decreased by the presence of Cd in Ganges, but not in Prayon. The superior capacity of Zn uptake in Ganges in the absence of Cd suggests that this ecotype has an additional Zn uptake system, which is suppressible by Cd.