Effects of Irrigation and Nitrogen Supply on Grain Yield,Water Use Efficiency and Apparent Nitrogen Recovery Fraction of Spring Wheat on No-tillage Farmland with Standing Stubble

A controlled experiment was conducted in oases of the Shiyanghe river basin to investigate the effects of different irrigation and nitrogen supply levels on grain yield,straw yield,harvest index(HI),water use efficiency(WUE) and apparent nitrogen recovery fraction(NF) of spring wheat on no-tillage farmland with standing stubble.A complete randomized block split-plot design was employed with different irrigation regimes,namely conventional irrigation of 327 mm,20% water-saving irrigation of 261 mm,40% water-saving irrigation of 196 mm,and nitrogen fertilizer application rates of 0,140,221,300 kg·hm-2,respectively.Under the experimental condition,the wheat grain yield,straw yield and HI increased with increase of the irrigation volume,and the WUE and NF increased at first and then decreased with the increase of the irrigation volume.The WUE and NF were the highest at 20% water-saving irrigation among different irrigation treatments.When the nitrogen supply level was 221 kg·hm-2,the grain yield of 6 365 kg·hm-2,HI of 0.49,WUE of 14.51 kg·mm-1·hm-2 and NF of 21.8% reached the maximum among different nitrogen treatments.Comprehensively considering for the grain yield,WUE and NF,the treatment of 20% water-saving irrigation combined with nitrogen supply level of 221 kg N·hm-2 was the best choice for wheat production in oases of the Shiyanghe river basin in Gansu Province on no-tillage farmland with standing stumble.