Durum Wheat Grain Quality Traits as Affected by Nitrogen Fertilization Sources under Mediterranean Rainfed Conditions

Abstract: Nitrogen application, environmental variation and particularly water deficit and terminal heat that prevail during post grain filling period could significantly affect not only grain yield ability but also quality related traits of durum wheat. A field trial was conducted to evaluate the effect of two nitrogen sources applied at different rates ranging from 0 to 93.8 KgN^-1 on yield and grain quality of three durum wheat cultivars. Increased N level from both nitrogen sources (ammonium sulfate nitrate: ASN and urea N) appeared to positively improve yield and grain quality. This effect was particularly significant when for N level superior to 40.2KgNha^-1. The average yield increase under maximum N level ranged from 3.23 to 3.37tha^-1for urea and ASN respectively. The cultivar Om Rabia appeared to better valorize nitrogen supply and was found associated with higher yielding ability of 1.78tha^-1, greater test weight 78.90kg/hl, grain protein content 12.43%, and gluten content 15.20%. This cultivar showed reduced yellow berry of 7.43% under N optimum application. Greater improvements were obtained for ASN than urea for all measured traits. The percentage increases were 6.09% for GY, 2.92% for TW, 4.48% for GP, 5.64% for Gl and 6.88% for CP. These results support that nitrogen derived from ASN and when its application rate is superior to 40.2 KgNha^-1 would promote grain yield and quality of durum wheat under rainfall conditions.