The yields, agronomic, and nitrogen use efficiency traits of wheat cultivars in north China under N-sufficient and -deficient conditions

In this study, the yields, yield components, agronomic, and nitrogen use efficiency (NUE) traits of the eighty-four winter wheat cultivars were investigated under nitrogen (N)-sufficient and -deficient conditions. Dramatic variations were observed in the yield and agronomic traits among the cultivars. Based on absolute yields under the N treatments, the cultivars were categorized into N efficiency groups of high, close high, medium, and low, in which the high efficiency group cultivars generally exhibited improved agronomic traits under these contrasting N-supply conditions. Additionally, the wheat cultivars were classified into various N response groups, including toleration, relative toleration, sensitive, and most sensitive based on the ratios of yield under N deficiency to that under N sufficiency. Regression correlation analyses revealed that straw biomass, total biomass, grain N amount, and straw N amount were significantly correlated with yield, suggesting that these traits can be acted as indices in evaluating yield potentials in wheat.