Course of Cation Absorption by Plant Tissue

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Science  22 Jun 1962:
Vol. 136, Issue 3521, pp. 1051-1052
DOI: 10.1126/science.136.3521.1051


The absorption of rubidium by excised barley roots from solutions containing calcium was a strictly linear function of time for 1 hour and was temperature-sensitive throughout; there was no evidence of an initial nonmetabolic exchange phase of uptake. The rubidium absorbed reached concentrations many times the external concentration without any slackening of the rate of absorption—evidence for a high degree of irreversibility of the overall absorption process. This is discussed in terms of the "enzyme-kinetic" model of ion transport by carriers.