Abstract
We investigated the difference in cadmium (Cd) amounts of caryopses among the positions of rachis-branch in an ear of paddy rice. The Cd amounts accumulated in the hulled grains varied among the caryopses in an ear, and the coefficient of variation of these amounts was more than twice as compared to that of grain weights. A negative correlation between the grain weight and Cd content percentage was observed, and the accumulation of Cd in small grains was greater than that in big grains. Cd accumulation in the rice grain was greatest in the caryopses set on the primary rachis-branch in the lower part of the ear. In a single rachis-branch, Cd was greatest in the caryopses set at the second and third positions in the primary or secondary rachis-branch. These results suggest that the variation of Cd accumulation in caryopses in an ear might be due to the difference of Cd accumulation between inferior and superior caryopses.
