| To evaluate the nitrogen use efficiencies (NUE) and their relationships with nitrogen nutritious characteristics of naked oats with eight different genotypes, a field experiment was conducted. Samples were collected at different growth stages and were then separated according to the tissue origins. After being dried, the samples were weighed and the nitrogen concentration was determined using semi-micro Kjeldahl method. The main results showed that the genotypes had significant effects on NUE (CV 11.98%～26.65%) but not on NHI (CV 5.04%). Additionally, NFE, as an integrated index reflecting the differences of grain yield and nitrogen utilization among different oat varieties, was significantly (P<0.05; P<0.01) correlated with NRE, NPP, indicating that it could be more useful in evaluating NUE. Moreover, NFE could be improved by increasing N assimilation and translocation after anthesis to effectively increase the N utilization in oat (r=0.7233**, r=0.7053**). Also, it was found naked oat could endure soil impoverishment (r=0.484*). However, excessive nitrogen was harmful (r=-0.701**). This research indicated that top-dressing nitrogen before anthesis could improve NUE effectively. At the same nitrogen levels, significant genotype effects of NRE and NFE caused remarkable differences among varieties, providing a rich variation basis for oat breeding. |