Assessing performance of European elite bread wheat cultivars under Mediterranean conditions: Breeding implications

Context or problem: Identifying traits conferring high yield in target environments has become a main concern of wheat breeders. This is particularly relevant for the current Mediterranean conditions as well as for the expected scenarios driven by climate change for central and northern Europe.Objective or research question: The objective of this study was to identify breeding traits conferring adaption of high-yielding European wheat cultivars to actual Mediterranean conditions.Methods: Twelve elite winter wheat cultivars from different European (northern, central and southern) regions were grown under Mediterranean continental conditions across three consecutive crop seasons and three different topdressing nitrogen fertilization levels. Phenology was assessed throughout the crop cycle. At maturity, grain yield (GY), grain number and thousand kernel weight (TKW) were determined. Further, carbon (delta C-13) and nitrogen (delta N-15) stable isotope compositions and nitrogen concentration (N) were analyzed in mature grains as proxies for water and nitrogen status, respectively.Results: The nitrogen fertilization effect was minor for GY compared with the season and genotypic effects. Concerning genotypic performance, the effect of phenology varied across seasons, with longer crop durations being associated with higher GY under the wettest season (2017-2018), no effect under mildly wet conditions (2019-2020) and being negatively associated with GY under dry conditions (2018-2019). Furthermore, the relative duration of each phenological stage had an effect on genotypic performance, particularly during the dry season (2018-2019). Moreover, regardless of the season considered, the highest-yielding genotypes were associated with better water status (lower delta C-13). Under wet season conditions, northern European genotypes had 6 % higher yields, whereas in the dry season, southern European genotypes had 2 % higher yields.Conclusions: The differences in GY among the top wheat cultivars originating from different European regions were fairly minor across the seasons and across the N fertilization levels recommended in the region. Implications or significance: The study suggests that, depending on the season, selection for the high-yielding conditions of central and northern Europe also delivers genetic increases in grain yield under Mediterranean conditions.