Rubidium and Potassium Absorption by Bean‐leaf Slices Compared to Sodium Absorption

Abstract

Abstract At salt concentrations of 0.1 m M as well as of 5.0 m M , the 22 Na + absorption capacity of bean ( Phaseolus vulgaris L. cv. ‘Brittle Wax’) leaf tissue increased during the period of leaf expansion and decreased rapidly after leaf maturation. The absorption capacity for 86 Rb + and 42 K + was highest in very young leaves and decreased continuously in expanding and in mature leaves. The 86 Rb + absorption capacity of mature leaves was not increased by detopping the plants; this senescence‐retarding treatment more than doubled 2 Na + absorption. The absorption of 22 Na + by bean‐leaf slices was not enhanced by light, whereas 86 Rb + and 42 K + absorption was much affected. Previously absorbed 86 Rb + and 42 K + were more available for exchange than 22 Na + .