[Effects of irrigation mode on winter wheat yield and water- and nutrient use efficiencies under maize straw returning to field].

In 2008-2010, a field experiment was conducted to study the effects of different irrigation modes on the grain yield, dry matter translocation, water use efficiency (WUE), and nutrient use efficiency (NUE) of winter wheat under maize straw returning to the field in a semi-arid and semi-humid monsoon region of Linfen, Shanxi Province of Northwest China. Irrigation at wintering time promoted tillering, irrigation at jointing stage increased the total tiller number and the fertile spike rate per tiller, whereas irrigation at booting stage promoted the dry matter accumulation in spike and increased the 1000-kernel mass. When the irrigation was implemented at two growth stages and the second irrigation time was postponed, both the dry matter translocation to leaf and the kernels per spike increased. Irrigation twice throughout the whole growth season induced a higher NUE and higher dry matter accumulation in spike, as compared to irrigation once. The irrigation amount at wintering time and the total irrigation amount had lesser effects on the tillering and the dry matter accumulation in spike. Increasing irrigation amount at jointing stage or booting stage more benefited the nutrient uptake, dry matter accumulation and translocation, and grain WUE, which in turn made the yield-formation factors be more balance and the grain yield be higher. It was concluded that to guarantee the irrigation amount at wintering time could achieve stabilized yield, and the optimal irrigation mode was irrigation at wintering time plus an additional irrigation at jointing stage (900 m3 hm(-2)), which could satisfy the water demand of winter wheat at its mid and later growth stage and increase the WUE of grain, and realize water-saving and high-yielding cultivation.