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This article in AJ

  1. Vol. 86 No. 3, p. 523-529
     
    Received: June 14, 1993


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doi:10.2134/agronj1994.00021962008600030013x

Phosphorus and Temperature Effects on Magnesium, Calcium, and Potassium in Wheat and Tall Fescue Leaves

  1. T. M. Reinbott and
  2. D. G. Blevins 
  1. Dep. of Agronomy, 1-40 Ag Bldg., Univ. of Missouri, Columbia, MO 65211

Abstract

Abstract

High K fertilization often reduces leaf Mg and Ca concentration, increasing the incidence of grass tetany, while increased P treatment increases uptake and leaf concentrations of Mg and Ca in winter wheat (Triticum aestivum L.). Since P availability and uptake are often reduced at low soil temperatures, the effects of P and K nutrition on mineral element composition of wheat at two root-zone temperatures were determined. The effects of P and NPK + Mg fertilization on leaf elemental concentrations of tall fescue (Festuca arundinacea Schreb.) grown in the field near Mt. Vernon, MO, on a Creldon silty clay loam (fine, mixed, mesic Mollic Fragiudalf) were determined. Concentration of Mg in wheat shoots was 20% higher when treated with 400 μM P than 50 μM P, and only 9% higher when root-zone temperature was 25°C rather than 15°C. Similarly, shoot Ca concentration was 11% higher with the high P treatment. Total plant Mg uptake was 60% greater and total Ca uptake was 51% greater with high P. The higher root-zone temperature increased total plant Mg uptake 38% and total plant Ca uptake 36%. Increasing K treatment from 400 to 800 μM decreased shoot Mg concentration 13% and shoot Ca concentration 7%. In the field, at soil temperatures <15°C, treatments of 20 or 28 kg ha−1 P increased both Mg and Ca leaf concentration of tall fescue. When leaf Mg and Ca concentrations in control plots were below 2.0 and 4.0 g mg−1 respectively, P fertilization increased Mg and Ca concentration above those thresholds considered likely to cause grass tetany. Fertilization with Mg increased leaf Mg concentration only when P fertilizer was added, but caused a decrease in leaf Ca concentration when no P fertilizer was applied. Leaf concentration and total plant uptake of Mg and Ca were more dependent on P nutrition than root temperature.

Research funded in part by the Missouri Lime and Fertilizer Council and the Foundation for Agricultural Research. Contribution of the Missouri Agric. Exp. Stn. Journal Series no. 11,942.

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