Effect of Nitrogen Rate and Timing on Quality Parameters of Durum Wheat (Triticum turgidum L.var. durum) Varieties in the Highlands of Bale, Ethiopia

Ethiopia is among the major wheat producing countries in Africa.Durum wheat is known for its gluten strength which is used for quality pasta and macaroni making.The gluten complex plays the major role in determining the technological quality of wheat.Wheat gluten proteins have unique visco-elastic properties of threedimensional structures formation.An experiment was conducted in 2007 and 2008 at three sites (Sinana, Selka and Robe) to determine the response of yield and quality parameters of durum wheat to nitrogen rate and timing.The treatments included 60 (30, 30), 60 (30, 30), 90 (30, 30, 30), 120 (30, 60, 30), 120 (30, 30, 60) and 180 (60, 60, 60) at planting, tillering and anthesis, respectively.It was found that there is significant difference between genotypes, locations, year and nitrogen rates and timing for sedimentation volume, vitreousness, dry gluten, wet gluten and gluten index except that there was no significant difference among genotypes for vitreousness and gluten index.Year x location interaction would not influence gluten contents but had significance for other parameters.The interaction of nitrogen by location and year was significant only for vitreousness.Most of the other cross other interactions were found not significant.The year effect was higher in 2007 for vitreousness, dry gluten and wet gluten whereas sedimentation volume and gluten index was higher in 2008.Rainfall during the growing months was higher in 2008 than in 2007 and this shows higher moisture related with lower gluten contents and vitreousness but with higher sedimentation volume and gluten index.The Robe site had higher vitreousness, dry gluten and wet gluten but lower sedimentation volume and gluten index.The Selka site had higher sedimentation volume but lower vitreousness, dry gluten, wet gluten and gluten index.The highest gluten index was obtained at Sinana on-station.Oda variety was found with higher gluten content and Bakalcha was with higher sedimentation volume.Increasing nitrogen levels was related with increasing gluten contents and vitreousness while gluten index decreased as nitrogen levels increase.Sedimentation volume decreased while vitreousness, dry gluten, wet gluten and gluten index increased with later application of N at anthesis than at mid tillering stage.