Introduction a result an increased emission of greenhouse gases (Ceotto 2005 David et al. Thus, selection in early generations can be done under high nitrogen fertilizer conditions as these provide a stronger differentiation, but the final selection in later generations should be conducted with a nitrogen fertilization as in the target environment. Nevertheless, the best performing genotype was always a different one.
High correlations of each trait between N levels and the rather low genotype-by-N-level interaction variance showed that generally the same genotypes perform well over different N levels. Furthermore, the effect of some QTL was dependent on the nitrogen fertilization level. Genome-wide association mapping revealed a complex genetic architecture with many small-effect QTL and a high level of pleiotropy for NUE-related traits, in line with phenotypic correlations. Analysis of temporal trends revealed that modern cultivars are better in exploiting the available nitrogen. For this, we evaluated 450 different triticale genotypes under four nitrogen fertilization levels in multi-environment field trials for grain yield, protein content, starch content and derived indices. The aim of this study was to evaluate nitrogen use efficiency (NUE) of triticale, investigate long-term genetic trends and the genetic architecture, and develop strategies for NUE improvement by breeding. Abstract Breeding high-yielding, nitrogen-efficient crops is of utmost importance to achieve greater agricultural sustain - ability. Key message The comparably low genotype-by-nitrogen level interaction suggests that selection in early generations can be done under high-input conditions followed by selection under different nitrogen levels to identify genotypes ideally suited for the target environment. Trini, Johannes Maurer, Hans Peter Würschum, Tobias Do lower nitrogen fertilization levels require breeding of different types of cultivars in triticale? Do lower nitrogen fertilization levels require breeding of different types of cultivars in.