Abstract
Two field experiments were conducted to investigate the effects of three drip irrigation regimes (G(1): 120% crop evapotranspiration (ETc), G(2): 100% ETc, and G(3): 80% ETc) and four nitrogen (N) source treatments (S-0: non-fertilized; S-1: urea, S-2: ammonium nitrate, and S-3: ammonium sulfate on water consumption use, water utilization efficiency, chlorophyll, yield and tubers quality of potato (Solanum tuberosum L.; cv Diamond) under a drip irrigation system during two successive winter seasons (2015/16 and 2016/17)). Nitrogen fertilization was applied at 380 kg ha(-1) as standard application for potato in the investigated area. The highest tubers yield was obtained from potato grown with G(1) S-2 (65.8 Mg ha(-1)), G(1) S-3 (63.6 Mg ha(-1)), G(2) S-2 (64.1 Mg ha(-1)), and G(2) S-3 (62.4 Mg ha(-1)), while the lowest tubers yield was obtained from potato grown with G(3) S-0 (10.1 Mg ha(-1)) and G(2)S(0) (17.4 Mg ha(-1)). Different treatments of N source resulted in a significant increase for water use efficiency (WUtE) compared with unfertilized treatment. For the interaction effect, the highest WUtE was obtained from potato grown with G(3) S-2 (18.1 kg m(-3)), followed by G(3) S-3 (17.6 kg m(-3)), while the lowest WUtE was obtained from plants grown with G(3)S(0) (3.0 kg m(-3)). However, the highest chlorophyll content was obtained from plants grown with G1 and any N source, followed by G(2)S(1-3), while the lowest chlorophyll content was obtained from those grown with G(3)S(0). The highest N, S, protein, and P contents in tubers were obtained from plants grown with G(3)S(3,) G(3)S(2), and G(2)S(2), while the highest K content in tubers was obtained from plants grown with G(1)S(1) and G(1)S(2). In concussion, the integrative effects of G(1) or G(2) with S-2 or S-3 is recommended for high productivity, while the integrative effects of G(3)S(3) and G(3)S(2) are recommended for high quality tubers.