Carboxylates and the uptake of ammonium by excised maize roots

H. Breteler

Research output: Thesisinternal PhD, WU


The effect of carboxylates (organic acid anions) on NH <sub><font size="-1">4</font></sub> uptake was studied by changing the carboxylate level of roots prior to uptake experi ments. Succinate was the most effective stimulator of ammonium uptake. The oxocarboxylates (α-oxoglutarate, oxaloacetate and pyruvate) and malate also promoted NH <sub><font size="-1">4</font></sub> entry. Preloading of roots with citrate, acetate, oxalate, glyoxylate or malonate reduced subsequent ammonium uptake. It is concluded that oxocarboxylates are important compounds in both the assimilation and the uptake process of ammonium. All carboxylates tested enhanced K uptake, but repressed NO <sub><font size="-1">3</font></sub> uptake, except citrate which increased nitrate absorption. Carboxylate stimulation of NH <sub><font size="-1">4</font></sub> entry showed metabolic as well as non-metabolic aspects.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Schuffelen, A.C., Promotor, External person
Award date14 May 1975
Place of PublicationWageningen
Print ISBNs9789022005705
Publication statusPublished - 1975


  • assimilation
  • experiments
  • in vitro
  • maize
  • nitrogen
  • organic compounds
  • phosphorus
  • plant physiology
  • plants
  • sulfur
  • zea mays

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