Effect of irrigation amount and water salinity on water consumption and water productivity of spring wheat in Northwest China

Sustainable development of agriculture is restricted by fresh water shortage and water quality deterioration in some arid and semi-arid areas. Therefore, deficit irrigation and saline water irrigation have to be applied for sustaining crop yield. In order to determine the rational irrigation management practice in an arid region of Northwest China, field experiments were conducted in 2008, 2009 and 2010 to study the effects of irrigation amount and water salinity on water consumption and water productivity of spring wheat. Altogether nine irrigation treatments including three levels of irrigation water amount with 375, 300, and 225 mm (w1, w2 and w3) and three levels of irrigation water salinity with 0.65, 3.2, and 6.1 dS m−1 (s1, s2 and s3) were arranged in a randomized split-plot design with three replications for each treatment. In 2008, yield increased with increasing irrigation amount under both fresh and saline water irrigation. However, in 2009 and 2010, the highest yield at the same salinity level under saline water irrigation was obtained by w2. Actual evapotranspiration (ETa) decreased with decreasing irrigation amount. Therefore, w2 got higher water use efficiency (WUE) (1.25–1.63 kg m−3) and irrigation water use efficiency (IWUE) (2.11–2.36 kg m−3) than w1, which indicated that irrigation amount 300 mm is beneficial to yield and water use efficiency at water salinity 3.2 and 6.1 dS m−1. Thus, for the purpose of highest yield and WUE, irrigation amount should be controlled at appropriate level under saline water irrigation. The effect of irrigation water salinity on ETa was significant in 2009 and 2010, while the effect on yield, WUE and IWUE was only significant in 2010. However, the differences of yield, ETa, WUE and IWUE between s2 and s1 were statistically insignificant in the 3 years. It can be concluded that irrigation water salinity 3.2 dS m−1 has no significant effect on wheat yield and water productivity. The interaction effects of irrigation amount and water salinity on yield, ETa and WUE were statistically insignificant in the experiments.

► Water consumption (ETa) under saline irrigation decreased with irrigation amount.
► Effect of salinity on ETa was more obvious under water deficit than sufficient.
► Water salinity 3.2 dS m−1 had insignificant effect on yield and water productivity.
► The maximum yield at 3.2 and 6.1 dS m−1 was obtained by irrigation amount 300 mm.
► Appropriately water deficit can elevate WUE and IWUE under saline irrigation.