Effects of interaction of water and nitrogen on the yield and component factor of hybrid cotton under mulch drip irrigation during flowering-boll stage.

【Objective】A field experiment,which was conducted to evaluate the effects of interaction of water management and nitrogen fertilizer on yield and water use efficiency of hybrid cotton No.2 Shiza during flowering-bolling stage in National Agricultural Science and Technology Area in Shihhotze in 2008,【Method】included seven water treatments(moderate drought 55% FC,55% field capacity of 0-60 cm profile under drip irrigation before irrigation),mid-drought(65% FC),contrast(75% FC),low irrigation quantity and high frequency(LH)(3 d 18 mm,irrigation with 18 mm every 3 days),high irrigation quantity and high frequency(HH)(3 d 30 mm),low irrigation quantity and low frequency(LL)(5 d 18 mm),high irrigation quantity and low frequency(HL)(5 d 30 mm)) and four nitrogen treatments(0,(fertilizing nitrogen with 0 kg/hm2),150,300 and 450 kg/hm2).【Result】The results showed that cotton yield decreased significantly under mid-water stress and moderate water stress during flowering-bolling stage under the condition of N0 N treatment and increased insignificantly with LL irrigation in each levels of N-application.The cotton yield with N450 kg/hm2 N-application was the highest under 75%FC irrigation condition,and cotton yield under the irrigation with 3 d 18 mm and 5 d 30 mm.When N application,the highest yield of 300 kg/hm2 was given,the seed cotton yield reached the highest level.With nitrogen increasing,the cotton yield decreased significantly in LH water treatment.Therefore,when treated with 5 d 30mm-N 300,the seed cotton had the highest yield,which was 7 426 kg/hm2,the treatment of 3 d 18 mm-N300 with seed cotton yield 7 018 kg/hm2 was the second selection of nitrogen and irrigation strategy.From the perspective of yield components of cotton,boll numbers per hectare,boll weight and lint were decreased significantly when drought or excessive water were used during flowering-bolling stage.【Conclusion】5 d 30 mm-N300 and 3 d 18 mm-N300 were the optimization irrigation strategy and nitrogen for hybrid cotton in Northern Xinjiang.