Effect Of Drip Irrigation Layout,Water And Nitrogen Supply On Yield And Quality Formation Of Winter Wheat In Xinjiang

In recent years,drip irrigation for wheat in Xinjiang has been rapidly developed.However,the relevant theoretical and technical research were scarced in terms of lacking coupled cultivation mode guidance,and the varied drip irrigation layout types with their miscellaneous water and fertilizer operations.For example,water and fertilizer supply is still following the traditional flooding period,which may restrict the advantages of drip irrigation,and eventually limit nutrient use efficiency and the yield.Regarding on this,this study aimed to explore the appropriate layout and amount of drip irrigation and nitrogen,three field experiments were carried out by using randomized block experimental design.The first one was about drip irrigation layout,and four treatments including one pipe for each 3 rows?treatment A?,one pipe for each 4 rows?treatment B?,one pipe for each 5 rows?treatment C?,one pipe for each 6 rows?treatment D?were conducted.The second experiment was about the irrigation amount,and five treatments including 3150 m3/ha?W₁?,3900 m3/ha?W₂?,4650 m3/ha?W₃?,5400 m3/ha?W₄?and 0 m3/ha?CK?.The third one was about nitrogen application rate,and six treatments that 0 kg N/ha?NO?,94.5 kg N/ha?N₁?,180 kg N/ha?N₂?,240 kg N/ha?N₃?,300 kg N/hm2?N₄?,360 kg N/ha?N₅?were designed.The cmain objective was to investigate effects of different treatments on characteristic of winter wheat canopy structure,photosynthetic properties,dry matter accumulation and distribution,uptake and use efficiency of water and nutrient,yield and quality,in order to provide a theoretical basis and technical support for high yield and water,fertilizer use efficiency of winter wheat cultivation.The results are as follow:1.Effect of different drip irrigation layout on winter wheat yield and water use efficiency The drip irrigation layout had significant effect on soil water content.From jointing to maturitystage,soil water content of 0-120 cm layer decreased following increased spacing interval,which was:A>B>C>D,and below 120 cm soil layer no difference in water contents was observed.With increasing spacing interval,spike,grain number,grain weight,yield of winter wheat and water use efficiency increased first and then decreased,with a order:B>A>C>D.Yield in treatment B reached 9381.01 kg/hm2,which was 4.49%,9.75%and 25.81%higher than A,C and D,respectively.2.Effect of drip irrigation amount on growth and development,yield and quality of winter wheatFor all the treatment,the amount of population dry matter accumulation and LAI all followed a order of W₃>W₄>W₂>W₁>CK during the whole growing process.With increasing drip irrigation amount,the assimilates translocation amount first increased and then decreased before flowers,while the assimilates accumulation increased after flowering.Maximal filling rate?Vm?increased first and then decreased,and the maximum was at W₃ in two years,which was 2.16 g/d and 2.59 g/d,respectively.With increasing drip irrigation amount,the grain unit weight,protein content,flour yield,wet gluten,dough stability time,degree of softening,dough extension resistance and draw ratio increased at first and decresed afterward,and the maximum was all showed at W₃.However,the water absorption rate and extensibility decreased initially and then increased,and the minimum value was at W₃.Besides,when the sedimentation value increased,dough development time was shortened.Water use efficiency?WUE?decreased following increasing irrigation amount.Among all the treatments,WUE of W₃ was higher than others,the maximum was 1.18 kg/m3 in 2013.The yield was following as W₃>W₄>W₂>W₁>CK.Overall,yield and quality of W₃ was the best.3.Effect of nitrogen application rate on characteristic of canopy and photosynthesis of winter wheat under drip irrigationWith increasing nitrogen application rate,both plant height and internode length increased first and then decreased,while transmittance at middle and bottom layer of canopy performed reserved trend,in which N₃ had the lowest light transmittance and the highest light interception rate.The canopy temperature of all the treatments consistently decreased from ear to the fourth leaf from flag,and the lowest was observed in N₃.Tendency of population LAI and SPAD after jointing was following a order of N₃>N₄>N₅>N₂>N₁>N₀.With increasing N application rate,the net photosynthetic rate of flag leaf,transpiration rate and stomatal conductance increased first and then decreased,and all of them reached the maximum at N₃,while N₃ had the minimum intercellular CO₂ concentration.4.Effect of nitrogen application rate on dry matter accumulation,yield and quality of winter wheat under drip irrigationUnder different N levels,dry matter accumulation at N₃ was the highest after jointing stage of winter wheat.Before flowering,assimilates translocation amount and rate,and the grain contribution rate all had the maximum at N₃.After flowering,assimilates translocation amount at N₃ was also the highest,but the grain contribution rate followed a trend of N₀>N₁>N₂>N₅>N₄>N₃.The accumulation amount of N?N?,P?P₂O₅?and K?K₂O?of winter wheat under different N levels all presented a trend of N₃>N₄>N₅>N₂>N₁>N₀.With increasing N application rate,grain unit weight,protein content,flour yield,wet gluten all increased first and then decreased;sedimentation value,dough water absorption rate,dough developing time and stabilization time,the maximum extension resistance and extension energy of the dough all followed a trend of N₃>N₄>N₅>N₂>N₁>N₀,while extension area and extensibility decreased gradually.The yield at N₃ was the highest among different N levels,and the average annual yield of N₃ was 8534.21 kg/ha.The agronomic nitrogen use efficiency presented a trend of N₁>N₃>N₂>N₄>N₅.The N harvest index of W₃ was the maximum.In synthesis,for drip irrigation of winter wheat in Xinjiang,we recommend that every 4 rows with a 60 cm space,4650 m3 water per heacter and 240 kg N/ha could be the optimal way to obtain high yield and quality of winter wheat.