Mechanism of Ion Absorption by Roots

Abstract

THE absorption of anions by barley roots has been studied in a manner similar to that adopted in a recent study¹ of the absorption of alkali cations. The earlier paper considered the effect on the rate of absorption of varying (1) the concentration of the ion whose absorption was being measured (arbitrarily called the ‘substrate ion’), and (2) the concentration of another alkali cation present (the ‘interfering ion’). The anion was chloride throughout. The results were shown to be consistent with the view^2,3 that the absorption of potassium and rubidium involves the formation and subsequent breakdown of an intermediate labile complex, MR, of the cation, M, with an ion-binding carrier, R. It was assumed that a membrane impermeable to the free ions is traversed by MR. Upon arriving at the inner surface, M is released through a chemical change in the carrier, R.