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Passive uptake of K + ( 86 Rb + ) in sunflower roots at low external K + concentrations
Author(s) -
Pettersson Sune
Publication year - 1981
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1981.tb02712.x
Subject(s) - helianthus annuus , sunflower , chemistry , diffusion , helianthus , passive transport , analytical chemistry (journal) , radiochemistry , membrane , physics , horticulture , biochemistry , environmental chemistry , biology , thermodynamics
Passive fluxes of K + ( 86 Rb) into roots of sunflower ( Helianthus annuus L. cv. Uniflorus) were determined at low K + concentration (0.1 and 1.0 mM K + ) in the ambient solution. Metabolic uptake of K + was inhibited by 10 −4 M 2,4‐dinitrophenol (DNP). K + ( 86 Rb) fluxes were studied both continuously and by time differentiation of uptake. In high K + roots passive uptake was directly proportional to the K + concentration of the uptake solution, indicating free diffusion. This assumption was supported by the fact that passive Rb + uptake was not affected by high K + concentrations. In low K + roots the passive uptake of K + was higher than in high K + roots. The increase was possibly due to carrier‐mediated K + transport. As K + effluxes were quantitatively similar to influxes, it is suggested that passive K + fluxes represent exchange diffusion without relation to net K + transport.