Department of Plant Sciences

For years the absorption and translocation of Fe in the plant from iron fertilizers have been studied using different approaches. In this work the advantage of the use of chelates enriched in the stable isotope 57Fe has been studied. Prior to biological assay, an interaction experiment with 57Fe chelates was performed to test whether isotopic exchange occurs between native Fe (mainly 56Fe) from soil and the 57Fe from the chelates using two stable chelate: o,oEDDHA/57Fe3+ and HJB/57Fe3+, and two less stable ones: o,pEDDHA/57Fe3+ and DCHA/57Fe3+. In this soil conditions a quite slow isotopic exchange could be observed, being the more stable chelates those that present the lower exchange. These results may be used to distinguish the source of the Fe in the biological experiment.

Soybean seeds (Glycine max L. cv Klaxon) were grown in a calcareous soil in a growth chamber. Two different experiments are presented in this work. In the first experiment 2.5 mg 57Fe/kg of soil as o,oEDDHA/57Fe3+; o,pEDDHA/57Fe3+, HJB/57Fe3+ and DCHA/57Fe3+ were applied. In the second one, different dose of o,oEDDHA/57Fe3+ and HBED/57Fe3+ were assayed. With the results obtained in both experiment we can concluded that the use of the isotope 57Fe allow studying the absorption pattern from the chelate and differences among the treatments assayed can be better observed. In conclusion, this technique can be used to evaluate the efficacy of new chelates as iron sources for plants grown in soils, since it allows confirming the origin of the Fe uptake by the treated plants.