Accumulation and radial transport of ions from potassium salts by cucumber roots.

Accumulation of K(+) is insensitive to the anion supplied with it at a solution concentration below 1 mm. Rates of K(+) transport to the xylem from the same solutions are, however, dependent upon the anion present and decrease in the order NO(3) (-) >> Cl(-) > SO(4) (2-). Parallel effects on rates of exudation and anion transport result from kind and concentration of anion supplied and time of exposure to the solution. When high K salt concentrations are used, only linear relationships are found between solution concentrations and transport rates. However, ion concentration in the exudate increases more than external solution concentration, while exudation rate is unaffected. It is suggested that some of the ions transported are from compartments within the cells. At high solution concentrations KNO(3) results in more exudation and in higher ion concentration in the exudate than is found with KCl.