Metabolism‐linked Binding of Rubidium in the Free Space of Wheat Roots and its Relation to Active Uptake

Components of the initial uptake and active transport of rubidium were studied in potassium‐starved and potassium‐rich wheat plants. A metabolism‐linked component of the initial uptake in the root was identified by means of DNP‐treatment. It was shown that there is a direct proportionality between the magnitude of the metabolism‐linked component of the initial uptake and the rate of active uptake. It is suggested that, in the free space, this metabolism‐linked ion binding represents an initial step of the active ion transport preceding the subsequent carrier‐mediated transport across the plasmalemma.