Characters of Zn and Cd Accumulation and Distribution in Leaves of Sedum plumbizincicola at Different Ages
不同生境下锌镉在伴矿景天不同叶龄叶中的富集与分布特征

Field plot experiment, pot trial and hydroponics culture were conducted to study the accumulation and distribution characters of Zn and Cd in the leaves of Sedum plumbizincicola at different ages. The results showed that young leaves had higher Cd concentrations than mature one when grew at field plot, but the situation was opposite for Zn. Glass house pot experiment results showed that for fourth extraction season, Zn concentrations appeared to be higher in mature leaves than young ones when Sedum plumbizincicola grew at low Zn and Cd contaminations soil (S1), Zn concentrations in young leaves were higher than in mature one when plants grew at high Zn and Cd contamination soil (S4). For the sixth extraction season, Zn concentrations in mature leaves were significantly higher than in young ones at both S1 and S4. For both seasons, Cd concentrations in young leaves were significantly higher than in mature ones, except for the sixth extraction season of S1. Under hydroponics culture condition, Zn and Cd concentrations in young leaves were all higher than in mature ones. Cd and Zn concentrations in both mature and young leaves increased with incubation time, peaked at day 56 d, in mature and young leaves the highest concentrations of Zn were 43 107 and 33 774 mg/kg (DW) (600 mmol/L Zn) while and the highest concentrations of Cd were 15 057 and 9 060 mg/kg (DW), respectively. These results showed that accumu- lation and distribution characters of Zn and Cd in young and mature leaves were related to Zn or Cd concentrations in growth medium, especially to soil available Zn or Cd concentrations, treated time of heavy metals, plant growth stage. Sedum plumbizincicola has preferential allocation habit of Zn and Cd into shoots, especially into young leaves.