Migration and Distribution Characteristics of Cadmium in Sphagneticola trilobata, S. calendulacea and Their Hybrid

Abstract:

In order to understand the migration and absorption characteristics of cadmium, the differences in absorption, migration and distribution of cadmium were studied in Sphagneticola calendulacea (indigenous congener), S. trilobata (alien invasive species) and their hybrid treated with Hoagland solution containing 200 μmol/L CdCl₂. The results showed that the cadmium concentrations in stems and leaves of three species gradually increased with the time extension of cadmium treatment, and the cadmium concentrations in leaves gradually matched that in stems, while that in roots of three species was always the highest. For the whole plant, cadmium concentration of the hybrid was also the highest under stress. After recovery growth, the cadmium concentrations in roots of hybrid, S. calendulacea, and S. trilobata declined by 50.4%, 35.8%, and 33.7%, respectively. Distribution pattern of cadmium in leaves of three species had not significant change treated with/without CdCl₂. The hybrid tended to accumulate cadmium in young and mature leaves. The cadmium concentrations gradually decreased from vein, internal vein and leaf edge of three species, which in internal vein of S. trilobata was the highest (2 766.3 μg/kg). Therefore, the hybrid displayed stronger ability to absorb, transport and transfer cadmium than its parents, suggesting that it had greater potential in phytoremediation in the future.

Key words:Cadmium;Sphagneticola;Hybrid;Phytoremediation;Heavy metal