Genetic improvement effects on yield stability in durum wheat genotypes grown in Italy

In durum wheat (Triticum durum Desf.) the improvement of yield stability represents an important component for agricultural progress worldwide. This work reports on the evaluation of the yield performance of 65 durum wheat genotypes (landraces, old and new cultivars with different years of release and advanced breeding lines), in a range of Italian environments to assess the changes in adaptation and yield stability achieved over the last century as results of the genetic improvement. The Additive Main effect and Multiplicative Interaction (AMMI) analysis was used to capture a large portion of the Genotype × Environment interaction (GE) sum of squares and to separate main and interaction effects. The breeding strategies adopted during the last decades have contributed to reduce the interaction of genotypes with environments selecting genotypes with better stability across a wide range of locations and years and modern genotypes outperformed the old ones in all test environments with a strong adaptability to improved fertility. The old cultivars were characterized by a minimal responsiveness to improved environmental conditions, showing an almost stable nominal yield in agreement with the concept of “biological” or “static” stability. In contrast, the modern cultivars were highly responsive to fertility improvements and showed a pronounced adaptation to high-input environments. Notably, within the group of modern cultivars two of them, Tiziana and Giusto, showed a high-yield stability in biological terms and a high nominal yield across the tested environments. Giusto and Tiziana were the best cultivars in terms of both nominal yield and minimal GE interaction, indicating that selecting for improved yield potential may increase yield in a wide range of environments.