The influence of chelating ligands DTPA and fulvic acids and of CaCO3 on the kinetics of uptake and translocation of Fe in maize plants was determined in solution culture. The absorption of Fe, as influenced by the chelating agents, varied in the order: FeSO4 > Fe-DTPA > Fe-FA (poultry manure) > Fe-FA (sludge). The absorption of Fe was reduced by CaCO3. Chelating agents counteracted the inhibitory action of CaCO3 to varying degrees. The translocation of Fe from root to shoot was enhanced by DTPA and FA. Translocation of Fe was reduced by CaCO3 but chelating agents minimized such effects. The Michaelis-Menten equation defined the kinetics of Fe uptake by plants. Two phase expression of a single uptake mechanism defined the uptake of Fe by plants. The kinetics data show that the affinity of carriers for Fe at low ambient Fe concentrations varied in the order: Fe-FA (sludge) > Fe-FA (poultry manure) > FeSO4 > Fe-DTPA. At high Fe concentrations however, the carriers did not have any effect.
Chelating agents, DTPA, fulvic acid, Fe, maize
