CADMIUM UPTAKE BY AND TRANSLOCATION WITHIN RICE (ORYZA SATIVA L.) SEEDLINGS AS AFFECTED BY IRON PLAQUE AND FE2O3

A hydroponics culture experiment was carried out to investigate the effect of iron plaque and/or Fe2O3 on Cadmium (Cd) uptake by and translocation within rice seedlings. Uniform rice seedlings grown in nutrient solution for two weeks were selected and transferred to nutrient solution containing ferrous iron (Fe2+) (30 mg/L) for 24 h to induce the formation of iron plaque on the root surface. Then rice seedlings were exposed to different level of Cd (1.0 mg/L and 0.1 mg/L), and simultaneously Fe2O3 was added into hydroponic system for three days. At harvest Cd content in dithionite-citrate-bicarbonate (DCB) extracts, roots and shoots were determined. The results of this study showed that iron plaque could sequester more Cd on root surfaces of rice seedlings, however, Fe2O3 reduced Cd adsorbed on root surfaces. Both of iron plaque and/or Fe2O3 did not block Cd uptake by and translocation within rice seedlings. Although iron plaque could alleviate Cd toxicity to rice seedlings under low concentration of Cd (0.1 mg/L) the root tissue played more important role in reducing Cd translocation into shoot. And the long period experiment of hydroponic and soil culture was still needed to verify the potential effect of iron plaque and/or Fe2O3 on alleviating Cd toxicity to rice seedlings.