Evaluation of Fe-N,N′-Bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetate (HBED/Fe3+) as Fe carrier for soybean (Glycine max) plants grown in calcareous soil

The efficacy of N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) as an Fe source in plant nutrition for soybean (Glycine max) plants grown in calcareous soil under controlled conditions was studied. The ability of ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,oEDDHA/Fe-57(3+)) and HBED/Fe-57(3+) at increasing concentrations and the long lasting effect were evaluated. In addition, iron nutrition was studied considering the Fe uptake from the chelates prepared with the isotope Fe-57. Further, the SPAD index, total Fe and Fe-57 content in plant were analyzed and soluble and available Fe-57 fractions in soil were determined over time. Doses experiment indicated that a higher concentration of HBED/Fe-57(3+) as compared to o,oEDDHA/Fe-57(3+) is necessary for obtaining the same Fe-57 absorption by the plant; however, these differences were found to be lower in the second sampling time as compared to the first one. This long lasting effect of HBED/Fe3+ was corroborated in the long term experiment. Moreover, it was found that the load of Fe in the pods was higher when using HBED/Fe-57(3+) than when o,oEDDHA/Fe-57(3+) was used. The soil extract analysis for each sampling time indicated that HBED/Fe-57(3+) presented a higher stability in soil than o,oEDDHA/Fe-57(3+) over time. The HBED/Fe3+ could be a long lasting alternative to EDDHA/Fe3+ for correcting the iron chlorosis of dicotyledonous plants grown on calcareous soils.