[Phytochrome-dependent ion-transport in pea seedlings].

Five to 6 day old dark-adapted dwarf and tall pea seedlings grown in water culture were illuminated for ten minutes with red light and/or ten minutes with far-red light, and 90 to 170 minutes later their roots were immersed in a 0.2 mM K(+) solution containing labeled (86)Rb(+). After two hours uptake the fresh-weights and radioactivities of the shoot organs were determined. It was found that red light inhibits K(+)uptake into internodes and promotes uptake into the plumula. The red-light effect on K(+)transport precedes the red-light induced growth inhibition of internodes and growth promotion of leaves and is abolished by far-red light given immediately after red. The red-light effect on K(+)transport is independent of the concentration of K(+) given to the roots in the range between 0.2 to 125 mM.