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Crop Science Abstract -

Potassium Absorption by Excised Barley Roots in Relation to Antecedent K, P, N, and Ca Nutrition1


This article in CS

  1. Vol. 15 No. 1, p. 7-10
    Received: May 20, 1974

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  1. K. Ohki and
  2. A. Ulrich2



In absorption studies with excised roots, the nutritional status of roots in relation to root growth has been difficult to assess prior to the absorption period. Since the antecedent nutrition greatly influences the subsequent K absorption, it is important to assess the nutritional status of roots undergoing ion absorption. Therefore, this study was initiated to determine the influence of antecedent nutrition of K, P, Ca, NO3-N, and overall salt status of excised barley (Hordeum vulgare) roots on K absorption.

Assessment of the nutritional status of the plants was made by comparing the analytical results of the excised roots to the corresponding critical nutrient value of 13.5 meq, 4.5 mmol, 2.9 meq, and 2.5 meq kg-1 fresh wt, for K, P, Ca, and NO3-N, respectively.

Under severe K deficiency, excised barley roots absorbed less K than comparable roots slightly deficient in K. Losses of K to the absorbing solution occurred from roots with high endogenous K. Excised roots from Pdeficient plants, low in endogenous K, absorbed less K than roots low in endogenous K with adequate P. Nitrogen deficiency alone did not increase the capacity for K absorption. Calcium deficiency suppressed K uptake primarily as a result of high endogenous K in Ca deficient roots. A combination of N deficiency and low endogenous K increased the capacity for K absorption. Low salt plants however, had the largest capacity to absorb K.

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