KHAN, T. A., NADEEM, F., GAO, Y., YANG, Y., WANG, X., ZENG, Z., and HU, Y.
Nitrogen (N), an essential macronutrient for crop growth and development, is well known for its economic losses and environmental hazards due to imbalanced application. Oat (Avena nuda L.), a food and fodder crop, is well adapted to marginal soils and requires minimum water and nutrients to produce biomass. A hydroponic experiment was conducted in China Agricultural University, Beijing, China to evaluate the morphological and physiological adaptations of oat to organic N (ON) and low N (LN) with respect to chemical N (CK as control). The results have shown that oat responded to different nitrogen supplies with response to LN having been the dominant one. Lowest SPAD value, net photosynthesis rate, transpiration rate, gas exchange and stomatal conductance showed that the oat was under LN stress. Highest level of root dry mass, as indicated by increased R/S ratio and C/N ratio, was at the cost of minimum nitrogen utility as depicted by increased nitrogen utilization efficiency in roots under LN. Accumulation of total soluble proteins and sugars elaborated the carbon allocation to nitrogen deprived roots. As a result of sufficient biomass provision in LN root, total root length increased which was coupled with increased concentrations of indole-3-acetic acid, gibberellic acid and zeatin riboside whereas decreased concentration of abscisic acid. Overall, oat is found to be a nitrogen use efficient crop which responded to LN through enhanced root system through biomass accumulation by the provision of nitrogen metabolites. [ABSTRACT FROM AUTHOR]