Effects of Zn and Cd Interaction on Cd and mineral elements accumulation in rice seedlings

The accumulative characteristics of Cadmium(Cd) and mineral elements in roots and shoots of Huanghuazhan and IR68144 seedlings under gradient Zinc(Zn) × Cd stress were studied. The results were as follows:(1) With the rising of Cd2 +concentration in nutrient solution, Cd content of Huanghuazhan and IR68144 roots and shoots increased significantly. The absorption of Cd in rice roots was effectively reduced by moderate concentration of Zn2 +at high concentration of Cd stress, but they showed synergistic absorption at low concentration of Cd stress.However, a high concentration of Zn2+promoted the absorption of Cd mainly. Rice shoots Cd accumulation could also be reduced effectively by moderate concentrations of Zn2 +under certain conditions, but its role depended on the concentration of Cd2+and rice genotype. Nevertheless, high concentration of Zn2+promoted the accumulation of Cd in all cases.(2) Zn content of roots and shoots from Huanghuazhan and IR68144 rose along with the increase of Zn2+concentration in the nutrient solution. The effect of Cd on Zn accumulation was related to Zn2+concentration and rice genotype, but in most cases the accumulation of Zn in rice reduced significantly under Cd stress.(3) In the nutrient solution with normal Zn2+concentration(0μM/L), along with the increase of Cd2+concentration, Fe accumulation in Huanghuazhan and IR68144 roots kept relatively stable, but it significantly reduced in shoots of both cultivars. At the same conditions, Mn content of roots from the two varieties increased, but that of Huanghuazhan shoot declined continuously while kept balance in IR68144. Zn ×Cd interaction on Fe accumulation mainly performed promoting effect in the roots, and chiefly showed inhibitory effect in shoots, but their effects on Mn accumulation were related to Cd2+, Zn2+concentration and rice genotype complicatedly. Zn×Cd interaction could effectively control the absorption and transport of cadmium in rice seedlings, but the interaction effects associated with Zn2+and Cd2+concentration in the nutrient solution, and showed a significant genotypic difference. Zn×Cd interaction also changed the Zn, Fe and Mn accumulation in rice seedlings.