Effects of Cd2+ ions on root anatomical structure of four rice genotypes.

Root anatomical structures of four rice breeding materials (maintainer lines YixiangB and E2B, restorer lines R892 and Mianhui725), grown under different Cd2+ levels, were observed and the root resistance to Cd2+ ions was evaluated. Under low Cd stress, the new roots appeared in the cortex of four rice genotypes. The diameter of the new root in YixiangB was larger than that of E2B. The restorer line R892 generated more roots than Mianhui725. Under high Cd2+ stress, broken epidermis, damaged cortex and black spots appeared in both maintainer and restorerlines. In general, anatomical damages in the restorer lines (R892 and Mianhui725) were slighter than those of the maintainer lines (YixiangB and E2B). Thus, the restorer lines had more adaptive ability to Cd2+ stress than maintainer lines.