Figure 3.

Interaction between NO₃ ^– and NH₄ ⁺ fluxes on root surfaces of B. campestris. (A) Influence of NO₃ ^– on net NH₄ ⁺ fluxes after adding 1 mmol L^–1 NH₄ ⁺ to the bathing solution with or without 1 mmol L^–1 NO₃ ^–. (B) Influence of NH₄ ⁺ on net NO₃ ^– fluxes after adding 1 mmol L^–1 NO₃ ^– to the bathing solution with or without 1 mmol L^–1 NH₄ ⁺. Changes in net NH₄ ⁺/NO₃ ^– fluxes in roots at 30 s intervals are presented. The vertical arrow indicates the point at which 1 mmol L^–1 NH₄ ⁺ or NO₃ ^– was added. t1–t4 represent the stages of net NH₄ ⁺/NO₃ ^– fluxes after adding NH₄ ⁺/NO₃ ^– to the bathing solution. The data represent the mean ± SE (n = 4–6) during the measurement period.