Evolution from durum wheat landraces to recent improved varieties in Morocco in terms of productivity increase to the detriment of grain quality

Durum wheat landraces have constituted until the first half of the last century, the main source of Moroccan wheat production. This local germplasm is still cultivated in less favorable environments, particularly in mountains and sub-Saharan regions. In recent decades of the 20th and early 21st centuries, the genetic improvement had led to the release of new durum wheat cultivars highly uniform and more productive. The present paper investigates the evolution of genetic variability in terms of productivity and quality related traits using an historical series of Moroccan durum wheat genotypes grouped according to their period of release into “Landraces/ Old cultivars”, “Intermediate cultivars” and “Modern cultivars”. A significant improvement was achieved in Moroccan durum wheat productivity. Modern cultivars exceeded their predecessors in terms of productivity related traits. The genetic gain was clearly associated with a reduction in plant growth cycle and plant height lowering the straw yield which resulted in an increase of grain yield estimated to 15.4 Kg/ha/year. However, results revealed a reduction in terms of almost all quality related traits; -0.12% per year for protein content, -0.30 % per year for gluten strength, -0.31% per year for yellow pigment content, and -0.19% per year for vitreousness. The results underline the important variability in grain quality attributes among landraces genotypes. This local germplasm may be used as sources of quality–improving attributes in durum wheat breeding program to develop new varieties combining both high productivity and grain quality.