Evaluation of Heavy Metal Toxicity on Radish: Comparison between Soil and Floating Hydroponics Systems

Two plant growing methods, namely use of soil and a floating hydroponic system, were compared in order to determine whether the response of radish to Cd, Cu, Ni and Zn was affected by the cultural system. Seed germination, plant biomass (root, shoot, hypocotyl), and heavy metal accumulation in different parts of the radish plants were monitored. The presence of heavy metals in the germination medium had no effect on seed germination, while the biomass of plants grown in hydroponics was negatively affected by the presence of metals in the nutrient solution. In both cultural systems, the amount of metals in roots, hypocotyls and shoots increased significantly with the increasing metal concentration in the growth media; the highest concentrations of heavy metals were found in the roots. The bioconcentration factor (BCF) and translocation factor (TF) values for the four metals were found to be considerably different between both growing systems. The different responses of plants suggest that in contaminated soils the plants are in the presence of lower quantities of available metals than those found in the corresponding substrates of the hydroponic system.