Potassium uptake by rice plants and interaction with other cations

Summary Rice plants were grown in nutrient solutions in which the K supply was varied by stepwise substitution of Na, Mg, or Ca. Curves relating concentrations in the tissues to those in the root medium showed that K uptake depressed the transfer of Na, Mg, and Ca into the shoots even when supplies of the latter were raised at the expense of K. Only when K was depleted did the other cations substitute for K in the shoots with little change in the total cation concentration in the tissue. Uptake appears to be controlled by a single system in which the 4 cations compete for uptake sites and K was the most effective competitor. re]19730507