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This article in SSSAJ

  1. Vol. 55 No. 6, p. 1612-1615
    Received: July 23, 1990

    * Corresponding author(s):
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Modeling Magnesium Uptake from an Acid Soil: III. Determination of Root Magnesium Concentration

  1. Z. Rengel 
  1. Dep. of Plant Science, Waite Agricultural Research Inst., Univ. of Adelaide, Glen Osmond, S.A. 5064, Australia



Research on the nutrient interactions in the rhizosphere of soil-grown plants would benefit from a reliable estimate of root-nutrient concentrations. Ryegrass plants (Lolium multiflorum Lam., ‘Wilo’) were grown for 35 d in a greenhouse on an acid Stough soil (coarse-loamy, siliceous, thermic Fragiaquic Paleudult) amended with three rates of CaO and two rates of MgCl2. Careful washing of roots in water was followed by a digestion procedure involving HF. Root Mg concentration was corrected for soil contamination based on Ti content in the root tissue. Titanium-corrected root Mg concentrations were lower than root Mg concentrations calculated by multiplying shoot Mg concentrations of soil-grown plants by the ratio of root to shoot Mg concentrations of solution-grown plants. Regression analysis showed that the Barber-Cushman model overpredicted total Mg uptake when root Mg content was calculated either from Ti-corrected root Mg concentrations (2.88 and 2.39 times for 0 and 36 mg Mg kg−1, respectively) or from root/shoot Mg concentration ratios in solution-grown plants (1.98 and 1.66 times for 0 and 36 mg Mg kg−1, respectively). Partitioning of Mg between roots and shoots of ryegrass may be quite different in soil- and solution-grown plants.

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