Physiological and biochemical processes related to ammonium toxicity in higher plants

Conference item

Nitrate and ammonium have different effects on many biochemical and physiological processes in plants, and at high concentrations this can lead to markedly different growth responses. Most plant species show reduced growth, smaller leaves and a stunted root system when exposed to high ammonium concentrations, and in severe cases this leads to chlorosis. Although well known, ammonium toxicity is poorly understood and is generally considered to be the result of one or more of the following effects: (i) ammonium-induced mineral nutrient deficiency, arising from the impaired uptake of metal ions; (ii) secondary growth inhibition arising from the acidification of the rooting medium; (iii) alterations in intracellular pH and osmotic balance; (iv) uncoupling of photophosphorylation from electron transport, following the accumulation of ammonium in leaves; and (v) altered polyamine and phytohormone metabolism. These hypotheses are reviewed in the light of the available literature and experimental evidence from own experiments. It is concluded that no mechanism on its own provides an adequate explanation of the available data. © VCH Verlagsgesellschaft mbH, 1997.

Authors: Gerendas, J; Zhu, Z; Bendixen, R; Ratcliffe, R; Sattelmacher, B

• Publication status: Published
• Host title: ZEITSCHRIFT FUR PFLANZENERNAHRUNG UND BODENKUNDE
• Volume: 160
• Issue: 3
• Pages: 239-251
• Publication date: 1997-06-01
• DOI: 10.1002/jpln.19971600218
• EISSN: 1522-2624
• ISSN: 0044-3263