Cadmium phytoremediation potential of turnip compared with three common high Cd-accumulating plants

Phytoextraction is a phytoremediation technique used for remediating polluted soils and it greatly relies on the plants' capacities to accumulate contaminants. Turnip is a high cadmium (Cd)-accumulating plant. We compared the Cd tolerance, growth, and Cd accumulation characteristics of two turnip landraces with three additional commonly known high Cd-accumulating species to systematically estimate its Cd phytoremediation potential. Results showed that the turnips could tolerate relatively lower Cd concentrations than other plants. Growth characteristics analyses indicated that the turnips initially grew rapidly and then gradually slowed down, and their photosynthetic parameters indicated that biomass accumulation was easily affected by light. However, the Cd uptake and translocation capacities of the two turnip landraces were higher than those of Phytolacca americana Linn. and Bidens pilosa Linn. but close to that of Brassica napus Linn.. Ultimately, large amounts of Cd accumulated in turnips during early growth and slightly increased as the fleshy roots increased in size. Based on these findings, the present turnip landraces have potential for soil remediation, but additional research is needed before these landraces can be practically used. Moreover, turnips are good candidates for studying the molecular mechanism of high Cd accumulation in plants.