Light sensitivity of na, rb, and k absorption by different tissues of bean leaves.

Autoradiographs of (22)Na-loaded bean (Phaseolus vulgaris L. cv. ;Brittle Wax') leaf slices showed that most of the tracer was concentrated in vascular tissue. Rubidium-86 was uniformly distributed in slices that had been incubated in darkness; after incubation in the light many small dark spots appeared on the autoradiographs, apparently corresponding with the stomata. Autoradiographs of (42)K-loaded slices showed a rather uniform distribution of the tracer, whether the slices had been incubated in light or in darkness.