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This article in AJ

  1. Vol. 85 No. 2, p. 322-328
    Received: June 7, 1991

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The Effect of Citrate and pH on Zinc Uptake by Wheat

  1. P. Chairidchai and
  2. G.S.P. Ritchie 
  1. Soil Science and Plant Nutrition, School of Agric., Univ. of Western Australia, Australia, Nedlands, Western Australia 6009



Zinc uptake by plants may be influenced by its reaction with organic ligands in the rhizosphere. Therefore, four experiments were conducted to examine the effects of an organic ligand (citrate) and pH on the uptake of Zn by wheat (Triticum aestivum L. emend. Thell). Plants were grown for 21 to 28 d in a nutrient solution (containing 0–0.05 μmol L−1 Zn) in a temperature controlled tank, either in the absence or presence of citrate and at constant or variable pH (3.7–7.1). Dry matter weights of plant parts and Zn content in the shoots were determined. The activities of Zn in the nutrient solution were estimated. Shoot dry matter of the wheat plants in each experiment correlated well with either ZnT/[H+] or Σ(moles Zn1charge)/[H+] (ZnT = total Zn, Zn1 = each zinc species). Both parameters could explain the relative shoot dry matter of the plants from all experiments in one equation (y = A + BE−cx; r2 = 0.79 and 0.77, respectively). In the absence of citrate, shoot dry matter as well as Zn content increased with increasing pH and increasing total Zn concentrations in solution. In the presence of citrate, the shoot dry matter of wheat plants that were grown in nutrient solution with constant pH increased with the total Zn concentrations. However, the effect of the total Zn concentrations in the solution containing citrate with variable pH were less important than the effect of pH.

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