Fig. 6.

Net fluxes of NH₄⁺ and K⁺ at the root surface are dependent on the external concentration of NH₄⁺. Arabidopsis Col-0 plants were grown on agarose plates with NO₃⁻ as nitrogen source and without K⁺ and NH₄⁺. Measurements were done at constant external K⁺ of 0.2 mM in bathing solution (0.1 mM CaCl₂).