Influence of calcium on selectivity of ion absorption process

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Abstract
Ca was found to have the property of markedly altering the ratio of absorption of Na and K by excised roots of barley (Hordeum vulgare). The presence of as little as 10-6 [image] Ca was sufficient to cause a detectable change in absorption rates. The effect of Ca was enhanced in mixtures of Na and K compared to its effect in single salt solutions. The relatively constant sum of the absorptions of Na and K from a mixture of the 2 ions in spite of large changes in the ratio of the 2 absorbed ions caused by the presence of Ca suggests a common metabolic carrier. Several polyvalent cations affect absorption similarly to Ca. It was concluded that the particular mechanism was either non-specific or that the other polyvalent cations interacted with Ca present in the roots. The controlling behavior of Ca was found in the roots of 6 different species of plants.