INVESTIGATIONS ON THE UPTAKE OF CADMIUM IN HYPERCUM PERFORATUM.L. (ST. JOHN'S WORT)

The cadmium concentration in Hypericum perforatum, grown on different soils resp. locations in Germany, is extremly high. This is caused on one hand by the Cd-content of the soils but on the other hand by the plant itself, because it belongs to the so called, "Cd-accumulation plants", that means the Cd-concentration, calculated on dm base is higher than in the soils measured in an aqua regia extract.

Under these conditions a limit for Hypericum perforatum of 0.5 mg Cd/kg dm is recommended by a commission of the governmental health service.

In the present investigations different origins of Hypericum perforatum grown in field and pot trails with varying Cd-contents in the soil were analyzed.

A strong positive correlation between the Cd-content in soil and the uptake by the plants was found out.

But it was also ascertained, that there are differences in the Cd-accumulation among the proveniences resp. genotypes. In most cases the above mentioned limit could not be kept. So, the selection of low accumulating types may be helpful in solving this problem.