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Soil Science Society of America Journal Abstract -

Role for Potassium in the Iron-Stress Response Mechanism of Iron-Efficient Oat


This article in SSSAJ

  1. Vol. 56 No. 3, p. 830-835
    Received: May 20, 1991

    * Corresponding author(s):
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  1. D. F. Hughes,
  2. V. D. Jolley  and
  3. J. C. Brown
  1. School of Natural Resources, Univ. of Missouri, Columbia, MO 65211
    Dep. of Agronomy and Horticulture, 275 WIDB, Brigham Young Univ., Provo, UT 84602



Adequate soil K enhances the ability of certain Fe-deficiency-stressed monocotyledonous and dicotyledonous plants to obtain Fe. In dicotyledonous plants, this increased capacity to obtain Fe where adequate K is present is associated with specific Fe-stress response mechanisms including H+ ion efflux, reductant release, and reduction of Fe3+ to Fe2+ at the root (Strategy I). A different Fe-stress response mechanism recently identified in Fe-efficient grasses is the release of phytosiderophore (a plant-produced Fe3+ chelator; Strategy II). Our objective was to determine if varied K additions affect either the production and release of phytosiderophores or the uptake of Fe in oat (Avena sativa L.; a Strategy II plant). A series of hydroponic experiments was conducted imposing varying solution K concentrations on Fe-deficiency-stressed ‘Coker 227’ oat, an Fe-efficient cultivar. Significantly more phytosiderophore was released by roots of oat plants grown with adequate K (84 mg K L−1) than by roots of plants grown at low concentrations of solution K (0 and 7 mg K L−1). The diminished phytosiderophore production in the absence of K corresponded significantly with greater Fe-deficiency chlorosis and lower leaf Fe contents. Oat plants grown in adequate K successfully competed with equimolar concentrations of Fe and EDDHA [ethylene-diamine di (O-hydroxyphenylacetic acid)], but did not compete for Fe where excess EDDHA was added, further substantiation of a role for K in the production and release of phytosiderophore.

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