Breeding effects on the genotype × environment interaction for yield of durum wheat grown after the Green Revolution: The case of Spain

This study evaluates the changes caused by breeding in the genotype by environment (G × E) interaction of the durum wheat varieties most widely cultivated in Spain after the Green Revolution. A set of 12 cultivars was tested in 27 environments, which are understood as the combination of different sites, years, and treatments (water regime and planting dates), representative of the durum wheat growing conditions in Spain with average grain yields (GY) ranging between 2.8 and 9.1 Mg ha⁻¹. The most important environmental factors affecting the G × E interaction for yield were themaximum and the mean temperature during the entire crop cycle. An improvement in genetic yield was observed in warm environments and under optimal water conditions that resemble those where the germplasm originated (essentially as advanced lines) before its release in Spain. Therefore, the adaptation of semi-dwarf durum in Spain has shown a tendency to specific adaptation rather than large-scale adaptation. Two different patterns of selection have been reported due the G × E interaction and changes in the ranking of genotypes: in the high yielding environments (GY > 5 Mg ha⁻¹), plants favor increased water uptake, with higher levels of transpiration and more open stomata (more negative values of carbon isotope composition, δ¹³C, and higher canopy temperature depression, CTD), whereas, in low yielding environments (GY < 5 Mg ha⁻¹) plants close their stomata and favor greater water use efficiency (less negative δ¹³C values and lower CTD values).