Nitrogen use efficiency (NUE) in rice links to NH4 toxicity and futile NH4 cycling in roots

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, and transmembrane NH4 + fluxes in the root meristem and elongation zones were determined. Results: We show that W23 possesses great..