Grain quality of Durum wheat (Triticum turgidum L. var. durum) varieties as influenced by nitrogen application at Sinana, South-eastern Ethiopia

Abstract

Shortage of improved varieties and low soil nitrogen status are some of the major constraints limiting durum wheat grain quality in Bale Zone in Ethiopia, which is the major wheat producing belt in the country. Therefore, an on-farm experiment was conducted in 2014/15 growing season at Sinana, south-eastern Ethiopia, to assess the effect of nitrogen fertilizer rate on grain quality of durum wheat varieties. Factorial combinations of four durum wheat varieties (Tate, Toltu, Dire and Inglizi) and six rates of nitrogen (0, 35, 70, 105, 140 and 175 kg N ha^-1) were laid out in a randomized complete block design (RCBD) with three replications. Among the cultivars studied Tate was superior in most quality parameters. The highest N level 175 kg N ha^-1 also gave in the standard quality range which is desirable for pasta making. The vitreousity of the cultivars also varied from 68.3% (Inglizi) to 95.4 % (Tate). Grain protein content (12.5 %, mb) of the cultivars ranged from 10.9 % (Inglizi) to 12.2 % (Tate). Other quality parameters studied such as particle size index, gluten index, SDS-sedimentation volume and Chopin alveograph (dough deformation energy, elasticity and extensibility) also varied depending on cultivars and N fertilizer rates used. Variety Toltu was superior to Chopin alveograph and the highest N rate (175 kg N ha^-1) gave the highest dough elasticity and extensibility. Variety Tate had the highest gluten strength (57.4 ml) as determined by SDS- sedimentation test. The maximum gluten index was obtained from Dire (71%) while the lowest was from Inglizi (36%).