Interactions Between Chloride and Nitrate Uptake in Citrus Leaf Slices

Abstract

Uptake of Cl into Citrus leaf slices is decreased by external NO₃. With 0.5 mM external CI, the decrease is smaller than that produced by equivalent amounts of Br, but with 10 mM external Cl the effects of NO₃ and Br are similar. Uptake of NO₃ is decreased by external Cl.

When slices are pretreated in KCl, KNO₃ or KHCO₃, giving high intracellular K salt concentrations, uptake of Cl and NO₃ again decreases. Effects of internal Cl and carboxylates can be distinguished, and uptake appears to be altered by internal ion levels in a manner analogous to that previously demonstrated with other plant tissues. The suggestion that leaf cells may lack some of the regulatory systems present in roots is discussed.