Plant materials and growing conditions: A total of 300 durum wheat genotypes comprising native cultivars and landraces as well as advanced lines and cultivars from International Maize and Wheat Improvement Center (CIMMYT) / International Center for Agricultural Research in the Dry Areas (ICARDA) were used in this study. The study was conducted in 1997-98 and 1998-99 growing seasons at two sites of Abarkoh (North latitude 31-degree 8 minutes and East longitude 53-degree 17 minutes, 1510 m asl) and Isfahan (North latitude 32-degree 32 minutes and East longitude 51-degree 23 minutes, 1630 m asl) located in central region of Iran. Abarkoh region is located in the marginal of Kavir desert and has always a warm and dry weather, particularly at grain filling period of autumn-grown cereal crops. An unreplicated trial with three-replicated-check cultivars (Shova, Altar84 and Aconchi89) was used at each of the locations. Fertilizer application was based on local practice of a rate of 40 kg ha^-1 of N and 60 kg ha^-1 Of P₂0₅ at all locations. The seed rate was 400 seeds m^-2 , and the harvested plot size was 6.25m² (5 rows, 5 m long, 25 cm apart).
Grain quality: Two grain samples were taken for each genotype from each of the successive years (1998 and 1999), combined into a single one and used in the present study. Hence, a total of 600 grain samples belonging to the two sites was evaluated for grain quality.

Weight per hectoliter (test weight), grain hardiness, protein content, wet and dry gluten contents and sodium dodecyl sulfate (SDS)-sedimentation volume were determined. Total grain nitrogen of flour was measured by the standard American Association of Cereal Chemists (AACC) Kjeldahl method (AACC 1962, 1983) and corrected to a 14% moisture basis. Grain hardiness was measured using Instron instrument.

The samples were tempered overnight to 16% moisture content and milled into semolina using a modified Buhler laboratory mill (Black and Bushuk 1967) with an extended mill flow to increase semolina yield. Semolina was milled into flour and the flour (10g) was mixed by hand for 20 s with deionized water to form dough ball. The dough ball was wrapped in an 1r silk sieve and hand washed under a flow of water for 50 s. The gluten ball was then worked between the fingers until it became sticky (about 5 min). Percent wet gluten content was determined by weighing the wet gluten ball after pressing it as dry as possible between the palms of hands for 30 s. Percent dry gluten was determined after drying the wet gluten ball by an oven at 70C for 48 h.

The sodium dodecyl sulfate (SDS)-sedimentation volumes were determined according to Preston et al. (1982) with some modifications suggested by Kovacs (1985) for durum wheat.