Copper accumulation and tolerance in Chrysanthemum coronarium L. and Sorghum sudanense L.

In the present study, the growth of Chrysanthemum coronarium L. and Sorghum sudanense L. and their copper accumulation were studied using hydroponic experiments. Results showed that the root elongation, dry biomass yield, and chlorophyll content in both plant species decreased significantly with the increasing level of Cu in solution. The concentrations of Cu in the two plants increased greatly with the increasing Cu level in the treatments. However, most of the Cu was accumulated in roots, and only a small portion was translocated into shoots. Compared with S. sudanense, the shoots of C. coronarium had a significantly higher concentration of Cu. The total amount and percentage of water-soluble Cu, and the nonprotein thiol were also higher in the shoots of C. coronarium. In the roots, however, S. sudanense accumulated more Cu than C. coronarium. The treatments with 5 to 50 mu mol L-1 Cu significantly increased the uronic acid content in the roots of S. sudanens, but did not have any significant effect for C. coronarium. Higher concentrations of Cu bound to the cell wall and uronic acid in the roots of S. sudanense were speculated to be the main reason to restrain Cu translocation from roots to shoots.