1 Journal of Agricultural Sciences Vol. 1(1), pp. 1-7 Jan. 2013 Available online at http://www.wynoacademicjournals.org/agric_sciences.html ISSN 2315-9162 ©2013 Wynoacademic Journals Nitrogen Fertilization Effects on Grain Quality of Durum Wheat ( Triticum turgidum L.Var.Durum) Varieties in Central Ethiopia. Gerba Leta 1 , Getachew Belay 2 & Walelign Worku 3 1 Corresponding author, ILRI/IWMI Addis Ababa, Ethiopia, E-mail: g.leta@cgiar.org ; 2 COMESA/ACTESA, Zambia, Email: getab62@yahoo.com & 3 University of Hawassa, Awassa College of Agriculture, Ethiopia: E-mail: walelignworku@yahoo.co.uk Accepted Date: 27 th December 2012 ABSTRACT Four released durum wheat varieties, two medium tall (Arsi-Robe and Kilinto) and two recently released semi-dwarfs (Ude and Yerer) were evaluated under five different N rates (0, 60, 120, 180 and 240 kg ha - 1 ) in 2005/06 growing season at Akaki and Debre Zeit, central Ethiopia. The quality responses of durum wheat varieties to different N-fertilizer rates and the N responses between tall and short durum wheat varieties were assessed. Protein and gluten content, vitreous kernel count, thousand kernel weight, test weight and lodging were considered. Vitreous kernel count, protein and gluten content were higher at Debre Zeit than at Akaki. Unlike Debre Zeit, there were significant relationships between response variables and fertilizer levels at Akaki. Lodging slightly affected the medium tall varieties at Debre Zeit whereas it was not a problem at Akaki. At Akaki, varieties response to each additional N rate was entirely below the quality standard set by ICC, 2000 except for thousand-kernel weight. Therefore, it is unwise to promote durum wheat scaling up/out program for quality durum wheat production at Akaki. Key words: Gluten Content, N-Fertilization, Protein Content, Thousand Kernel Weight, Test Weight and Vitreous Kernel Count. INTRODUCTION Durum wheat (Triticum turgidum L. var. durum) is the second most important wheat species grown in the world next to bread wheat (Triticum aestivum L.). It is the best wheat for pasta products due to its strong gluten, excellent amber color and superior cooking quality (Abaye et al., 1997; Pitz, 1992). It has been cultivated in Ethiopia for thousands of years. However, it has been gradually replaced by bread wheat. Currently, the growing demand for pasta is enhancing durum wheat production. Low volumes and poor quality of the national wheat production compels Ethiopia pasta industries to import the required raw material (Maria Grazia, 2012). As a result, the pasta factories annually import about 0.2 million tons of durum wheat. The quality of durum wheat is also highly dependent on the protein content of the grain, which is largely dependent on genotypes and influenced by environment, especially nitrogen (N) availability of the soil (Gooding and Davies, 1997). In Ethiopia durum wheat is largely grow on central highland vertisols. Vertisols in Ethiopia and other part of Africa generally have soil pH ranging between 7.5- 8.5 in the soil profile (Virman et al., 1982). This high pH content of the vertisols favors gaseous loss of ammonia when urea or ammonium fertilizers are applied to the surface (Terman, 1979; Sahrawat, 1980). On the other hand, the low infiltration rates of vertisols could also create environment favorable for denitrification since O 2 diffusion rate in water is very low (Russel, 1977). Thus, nitrogen fertilization of durum wheat in Vertisols is therefore important to mitigate the risk of N losses and to improve the quality of grain. Although Ethiopia is the largest producer in sub-Saharan Africa, little emphasis was given on improving the quality of durum wheat in the past. Currently, the national research institutes and pasta processing industries are jointly working to improving durum wheat grain quality. Increasing domestic quality produce could mitigate the shortage and substitutes the import of huge industrial raw materials. It also enables resource poor farmers fetch premium price. Therefore, it is vital to study soil fertility management practices across locations to improve the quality and market demand for the crop.