Abstract
Aims Rice is known as an ammonium (NH4)-tolerant
species. Nevertheless, rice can suffer NH4 toxicity,
and excessive use of nitrogen (N) fertilizer has raised
NH4 in many paddy soils to levels that reduce vegetative biomass and yield. Examining whether thresholds of NH4
toxicity in rice are related to nitrogen-use
efficiency (NUE) is the aim of this study.
Methods A high-NUE (Wuyunjing 23, W23) and a
low-NUE (Guidan 4, GD) rice cultivar were cultivated
hydroponically, and growth, root morphology, total N
and NH4 concentration, root oxygen consumption,