Impact of simultaneous Cd and Zn substrate amendments on metal accumulation in two Cd/ Zn hyperaccumulating Thlaspi species

Abstract

The impact of simultaneous Cd and Zn amendments in the substrate on the accumulation of Cd and Zn were studied in a recently discovered Cd/ Zn hyperaccumulating Thlaspi praecox (Brassicaceae) and compared to a model hyperaccumulating plant species T. caerulescens. The plants were grown in pots with added Cd or Zn or both for three months in a greenhouse. The addition of Zn in the substrate increased Cd extractability in the substrate significantly without a significant pH change and this increase resulted in increased concentration and content of Cd in the shoots of both species indicating that species have similar abilities to extract Cd from the substrate. In the combined treatment (Cd and Zn) an increase in shoot biomass accompanied with a decrease in Zn concentration in roots and shoots of both species was observed, while no changes in total accumulated Zn in shoots were seen. These results suggest different uptake and translocation systems for Cd and Zn in T. praecox, positioning this plant species in the superior Cd hyperaccumulating league of T. caerulescens Ganges ecotype.