Improvement of durum wheat yield and associated effects on morpho-physiological characters

Six durum wheat ( Triticum turgidum var. durum check for this species in other resources ) cultivars released in the central highlands of Ethiopia from 1967 to 1992, were evaluated to estimate progress in improving grain yield, and to determine changes in crop morphological and physiological attributes. The six durum wheat cultivars differed in all crop parameters studied. Over the 25 year period represented by the varietal releases, grain yield increased by 68 kg ha-1y-1 (1.58%y-1). Grain yield of durum wheat was positively correlated with harvest index, grains m-2, grains spike-1, grains spikelet-1, and thousand grain weight, all of which increased significantly over time. Spike density (ie., spikes m-2) decreased slightly while the other parameters did not exhibit significant temporal trends. Protein yield increased over time along with grain yield, while grain protein was unchanged. The national durum improvement programme has substantially improved the grain yield of rainfed durum wheat by increasing the magnitude of the grain sink and the efficiency of assimilate partitioning into grain. Durum breeders in Ethiopia should emphasise spike fertility and kernel size as reliable selection criteria for continued improvement in yield potential.