Evaluating nitrogen use efficiency and grain traits in hulless and hulled barley genotypes using Exhaustive CHAID and GT biplot

Hulless barley has attracted considerable interest due to its nutritional qualities and relevance in the food industry. However, information on the nitrogen use efficiency (NUE) of hulless barley remains scarce. In order to identify optimal nitrogen input strategies for yield and quality of barley, this study evaluated NUE, grain yield (GY), grain nitrogen rate (GNR), and related yield components in 2 hulless and 8 hulled barley genotypes across four nitrogen levels (0, 90, 180, and 270 kg ha−1). Statistical analysis included analysis of variance, Exhaustive CHAID (Chi-square automatic interaction detection), and genotype-by-trait (GT) biplot. Field trials were conducted according to the split block design with three replications in 2020 and 2021 growing seasons. Hulless genotypes Ozen and Yalin underperformed in most traits except GNR. NUE, defined as grain yield gain per unit N applied, did not consistently reflect a higher GY potential since low GY in control plots could inflate NUE. Both GT Biplot and Exhaustive CHAID separated barley genotypes: Larende and Egebeyi genotypes yielded higher GY and NUE under higher N doses when other genotypes leaned toward higher GNR. Selecting barley genotypes with inherently high GY potential would yield optimal results in all N doses in terms of NUE, grain yield and quality. GT Biplot and Exhaustive CHAID analyses proved effective for identifying barley genotypes with higher GY potential and optimizing N input in agricultural systems.