Agronomic and physiological traits related to the genetic advance of semi-dwarf durum wheat: The case of Spain

•Traits associated with genetic gains in yield may inform future breeding strategies.•Genotypic differences exist in modern durum wheat cultivars released in Spain.•Kernels per spike is the main agronomic component determining yield improvement.•Delayed senescence is a negative trait related to limits on sink accumulation of N.•Higher yielding genotypes exhibit better water status across Mediterranean conditions. Knowledge of the agronomic and physiological traits associated with genetic gains in yield is essential to improve understanding of yield-limiting factors and to inform future breeding strategies. The aim of this paper is to dissect the agronomic and physiological traits related to genetic gain and to propose an ideotype with high yield that is best adapted to Spanish Mediterranean environments. Six semi-dwarf (i.e. modern) durum wheat genotypes were grown in a wide range of growing conditions in Spain during two successive years. Diverse agronomic, physiological and leaf morphological traits were evaluated. Kernels spike−1 was the yield component most affected by the genetic gain. While no interaction between genotype and growing conditions existed for grain yield, the more productive genotypes were characterized by a plant height of around 85 cm, small erect flag leaves, more open stomata, a better balance between N sources and N sinks and a higher capacity to re-fix CO2 respired by the grain. Moreover, in general the non-laminar parts of the plants play a key role in providing assimilates during grain filling. The high heritability of most of the studied parameters allows their consideration as traits for phenotyping durum wheat better adapted to a wide range of Mediterranean conditions.