HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Oertli, J. J. Articles by Opoku, A. A. Search for Related Content PubMed Articles by Oertli, J. J. Articles by Opoku, A. A. Agricola Articles by Oertli, J. J. Articles by Opoku, A. A.

Effect of Macronutrient Ions on the Availability of Iron from a Chelated Source¹

ABSTRACT

The uptake of Fe from FeEDDHA [ferric chelate of ethylenediamine di (o-hydroxyphenylacetic acid)] during periods of 1 to 2 days was studied with 10- to 11-day-old corn plants (Zea mays L.) grown in nutrient solutions. The Fe in roots and tops was markedly affected by the composition of the nutrient solution. Cations stimulated Fe in plants in the following order: K> Na > Mg > Ca, and anions SO₄ > Cl > NO₃. The stimulation was the greater the more the pH declined during the absorption experiment; hence it was concluded that the effect of nutrient solution composition on Fe nutrition must be attributed to the imbalance of cation and anion uptake rather than to a specific nutrient. The pH decline and, in general, the associated stimulation of Fe uptake were enhanced by increasing concentrations of the interfering ions and by time. However, when the pH fell toward a value of 4, injury to roots occurred and Fe uptake was reduced in spite of a higher supply. The composition of the nutrient solution was also effective in long-term experiments in regulating Fe uptake. A decrease in pH resulting from excess cation uptake favors the formation of less dissociated forms of the free ligand, namely of (ligand-H)^3-, (ligand-H₂)^2-, etc., instead of the reactive ligand, (ligand)^4- and equilibrium can be maintained only if more FeEDDHA dissociates, liberating Fe³⁺ for uptake.

¹ Contribution of the Dep. of Soil Sci. and Agr. Eng., Univ. of California, Riverside 92502.

² Professor of Soil Science and former Graduate Student, respectively, Dept. of Soil Sci. and Agr. Eng., Univ. of California, Riverside.

Received for publication September 26, 1973. Accepted for publication March 18, 1974.