ABSTRACT
Nitrogen (N) is one of the most important nutrients for barley, and at the same time excessive N fertilization can have a negative impact on the environment. A 2-year field study was conducted with the objective to determine the relationship of N Use Efficiency (NUE) and its components N utilization efficiency (NUtE), and N uptake efficiency (NUpE) with N diagnostic tools N nutrition index (NNI) and chlorophyll meter (CM) readings of barley. CM readings were negatively correlated with NUE and NUpE. NNI varied from 0.79 to 1.00 across years and cultivars. This study provides new information about the effect of N application on NUE and its components and its relationship with CM readings and NNI of barley which can be used for proper N management and protection of the environment.