The Effect of pH and Temperature on the Absorption Of Potassium and Bromide by Barley Roots2

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Abstract
PH and temperature markedly influenced the absorption of K+ and Br~ by excised barley (Hordeum vulgare) roots even over the physiological range. The results obtained were consistent with the general formulation for the absorption reaction involving H+ for cation uptake and OH" for anion uptake. In view of the pH and temperature dependency of absorption, the significance of Q10 values was questioned. Apparent free space ions were shown to be of relatively small magnitude compared to absorbed ions when the latter was large compared to the solution concentration. Absorption behavior was found to vary with different varieties of barley, different seed batches of the same variety and different storage ages of the same seed. Because of the observed variability of absorption behavior, it appeared doubtful that any mechanism of absorption based on similarities to known kinetic models and dependent upon restricted experimental data would be generally applicable.
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