アヤメ科植物によるカドミウムの吸収除去に関する研究

抄録

Recently the lower criterion on cadmium (Cd) concentrations for polished rice was suggested in CODEX. It is urgently necessary to find out the most effective phytoremediator to remove Cd from rice fields. We have selected Iris pseudoacorus L. and Iris ensata Thunb. for our study from the following reasons; Iris pseudoacorus L. is known for its high biomass and strong resistance to environmental impacts: Iris ensata Thunb. have been often planted in the rice field in fallow. Both species are recognized by their beautiful flowers, commonness, the low prices and the easiness of planting. This experiment is aimed to evaluate these two species as phytoremediators to remove Cd. These plants are planted into 1ppm, 10ppm, 100ppm Cd hydroponics for 7 days. In general, Cd uptake by plants increases according to the Cd level of the hydroponics. The Cd removal rates of Iris pseudoacorus L. are between 0.64 and 2.00% (g/DW), while those of Iris ensata Thunb. are between 0.48 and 4.33%. Iris ensata Thunb. showed the higher efficiency in the low Cd concentration, whereas Iris pseudoacorus L. indicated an advantage under the high Cd concentration. Both Iris pseudoacorus L. and Iris ensata Thunb. indicate high Cd concentration in their roots but low in their shoots.