Quality attributes associated with breeding progress in Moroccan durum wheat released between 1984 and 2007

Improving grain quality has become one of the important breeding goals in several Mediterranean countries. This study assesses the changes in the quality of durum wheat developed in Moroccan over 30 years. Six leading varieties were grown under rainfed and irrigated trials during three seasons. Vitreousness, pigment content, test weight, and thousand kernel weight were evaluated as technological traits. Protein content, ash content, and the sodium dodecyl sulfate (SDS) sedimentation test were analyzed as nutritional traits. Except for pigment content, which was shown to be impacted by the period of release, the combined ANOVA revealed highly significant effects of water regime and growing season on all quality attributes. The results revelated that most nutritional traits were better expressed under rainfed conditions, while a marked increase in technological traits was observed in irrigated trials. Protein and pigment contents increased significantly under rainfed conditions with an annual genetic advance of 0.104% year –1 and 0.038 ppm year –1 , respectively. Vitreousness also showed an increasing trend at a rate of 0.497% year –1 under irrigated conditions, and 0.7% year –1 under rainfed ones. SDS volume exhibited a negative linear trend with the year of release in both water regimes. Contrariwise, there were no significant variations in ash content, thousand kernel weight, test weight, and thousand kernel weight between old and modern varieties. These findings suggest that during the last three decades, breeding efforts have improved the quality of durum wheat varieties in terms of protein and pigment content, and vitreousness.