[Effect of CCCP and UO 2 (++) on ion fluxes in roots].

Using the device shown in Fig. 1 of a previous paper (Weigl, 1969) efflux of Rb(+) from preloaded corn roots across the plasmalemma of root cortex cells was stimulated by addition of 5×10(-4) M UO 2 (++) , whereas the flux of Rb(+) into the xylem was inhibited by addition of 5×10(-4) M UO 2 (++) . Efflux of Cl(-) across the plasmalemma was stimulated by 10(-5) M CCCP, the flux of Cl(-) via the xylem was inhibited by 10(-5) M CCCP. The problem of interpreting efflux experiments with roots is stated and discussed.