Nitrogen and water use efficiencies and yield response of barley cultivars under different irrigation and nitrogen regimes in a semi-arid Mediterranean climate

Abstract

Experiments were conducted to determine barley cultivars (Yousef_six-rowed and Nimrouz_two-rowed) response to different water and nitrogen (N) regimes at Fars Agricultural Research Center using split-split-plot design. There were three levels of water regimes (full-irrigation (I₁₀₀), 75% and 50% of I₁₀₀: I₇₅ and I₅₀, respectively) in 2010. Rainfed treatment (I₀) was included in 2011. Three N levels (0, 60 and 120 kg ha⁻¹) were used. Grain and biomass water use efficiencies (WUE_g and WUE_b, respectively) were positively affected by N supply. The I₇₅ improved WUE_g and WUE_b by 17% and 20% as compared to I₁₀₀, respectively. Two-rowed cultivar showed higher WUE_g and WUE_b than six-rowed. Nitrogen use efficiency (NUE) was negatively affected by water stress and N fertilization. The highest grain yield was achieved by 120 and 60 kg N ha⁻¹ under I₁₀₀ and drought stress conditions, respectively. Two-rowed cultivar showed significantly higher NUE and grain yield than six-rowed cultivar under I₅₀ and I₀; by contrast, six-rowed cultivar had similar or higher performances in terms of these traits under I₁₀₀ and I₇₅. This study showed that optimizing irrigation and N rates and selection of suitable cultivars in semi-arid Mediterranean climate might increase NUE, WUE and produce economic grain yield.

Keywords:

• barley cultivars
• grain yield
• nitrogen use efficiency
• water use efficiency