Durum wheat is a good source of protein. A grain protein content of 13% for durum is a standard in quality throughout the grain industry (Riley et al. 1998). Protein content like other traits in wheat is known to be affected by genetic and environmental factors mainly location (Bement et al. 2003). In this study we evaluated a set of 25 genotypes comprising introduction from CIMMYT and advanced lines developed through hybridization by the Ethiopian National Durum Wheat Research Project (NDWP) for protein content over six testing locations, representing the wheat agro-ecologies in the country. The experiments were conducted in a randomised complete block design (RBD) with three replications each. Plot size was kept at 2 m
. Grain protein content was analyzed following Kjeldahl method (A.A.C.C. 1983). Stability analysis was done according to Eberhart and Russel (1966) model and effect of locations and its interaction with genotypes were estimated following additive main effects and multiplicative interaction (AMMI) model. The mean grain protein content varied from 11.61 to 13.52% among the genotypes. Only three genotypes, namely CD98206, DZ3117 and DZ-04-118 attained higher grain protein content than standard 13.00%. Stability analysis revealed that all but three genotypes were observed to be predictable. DZ 2212-1BS was found suitable for favorable environments. Genotype CD97383 was found sensitive to change in environment. Eight genotypes were identified as stable. Genotypes DZ3117 was found to be the best having maximum protein content recorded at AlemTena location and higher yield with stable performance across locations. AMMI analysis revealed that the first two significant IPCA scores together explained 73.55% of the total interaction variance. Biplot graphical analysis showed Alem Tena as the best location followed by Debre Zeit and Minjar in terms of average protein content of genotypes. Genotype DZ1669-1AK scored zero and could be considered as stable and wide adaptable having protein content higher than the general mean. The graphical analysis of IPCA 1 and IPCA 2 further revealed that this genotype was relatively close to origin zero. Genotype DZ-04-118 was adapted to Debre Zeit and Minjar while a large numbers of genotypes with negative IPCA score were adapted to Akaki and Chefe Donsa locations. Genotype DZ3117 had specific adaptability to Alem Tena location. High protein but low grain yield at Alem Tena may be due to the drought occurrence during grain filling period.