Effects of irrigation stage and amount on hybrid seed yield of maize and water use of maize in Hexi Corridor of Gansu

A two-year field experiment with hybrid maize variety No. 1 Jixiang was conducted to examine the effects of irrigation amount and stage on seed yield and water use efficiency( WUE) at Liangzhou,Wuwei,Gansu,China. Results indicated that,with rainfall of 128. 2 mm in 2012 and 98. 1 mm in 2013 during growing season of maize,avarage seed yield decreased by 41. 6% as irrigantion amount reduced by 56. 2% ranged from 480 mm to210 mm,and seed yield increased 14. 05 kg·hm- 2when 1 mm additional irrigation water was supplied. Compared with high irrigation treatment of 480 mm,the yield decreased by 0. 47% ~ 8. 26% and 8. 66% ~ 24. 90% in moderate irrigation treatments of 360 mm and 330 mm. There were great differences in effects of irrigation applied at maternal silking and tasselling and middle filling stages,and for yield reduced effects due to irrigation amount decrease were followed by three stages decrease of irrigation at the same time two stages alternating irrigation decrease a stage decrease of irrigation. Seed yield reduction was 6. 5% and 7. 2% with 60 mm irrigation at silking stage in contrasting to taselling and middle grain filling stages,and 11. 2% and 8. 5% with 30 mm irrigation at the same stage,respectively. No matter how the year,water use efficiency( WUE) increased with the increase of irrigation amount and evaportranspiration( ET),and high WUE value was obtained at moderate irrigation treatmentbut not at high irrigation treatment with high yield. Changes of WUE and IWUE( irrigation water use efficiency)values were same to seed yield changes,and the decreased amount of irrigation at maternal silking stage resulted in WUE and IWUE reduction,but did not at tasselling and middle grain filling stages. It concluded that considering of hybrid seed yield and water use changes,reduction of 25% ~ 30% in irrigation amount did not decrease seed yield,and maternal silking stage of maize was most sensitive to irrigation,suggesting reasonable irrigation would be at pre-silking and middle-late grain filling stages to achieving water-saving and yield-increasing.