Kinetics of iron absorption by excised rice roots.

Studies on the rate of iron absorption by excised rice roots from solutions of different concentrations of FeSO4 showed the presence of two patterns, one in the low (0.005-0.5 mM) and the other in the high (1-30 mM) concentration range. The presence of CaSO4 or MnSO4 at 0.5 mM enhanced Fe(++) absorption in the low concentration range, while CaSO4 at 10 mM inhibited Fe absorption in the high concentration range in a competitive manner. Fe(++) absorption at both low and high concentrations was sensitive to metabolic inhibitors. The isotherm for Fe(++) absorption at O° exhibited an initial absorption shoulder in both low and high concentrations and was suggestive of a latent ion-transport capacity for Fe(++) in rice roots.