Irrigation Management For Drip Irrigated Spring Wheat In Northern Xinjiang Province Based On AquaCrop Model

[Object] Knowledge about the water requirement of drip irrigated spring wheat under different environment conditions is able to improve the water use efficiency,providing a theoretical basis for the development of precise water management plan in Northern Xinjiang Province.[Methods] AquaCrop,the FAO recommended crop water productivity simulation model was introduced for drip irrigated spring wheat production in northern Xinjiang province.The experiment data of irrigated spring wheat production under different irrigation regime in 2009 and 2011 was used in model to localize calibration and verification.The model that has been calibrated was used for simulating and analyzing the net drip irrigation requirement of spring wheat under annual precipitation type,planting date,threshold of root zone depletion,soil texture,groundwater level,initial water content in soil profile.And the irrigation regime of drip irrigated spring wheat for different levels of irrigation frequency and irrigation quota under different rainfall year type was simulated.[Results]1.After the calibration and verification,a series of model parameters for the drip irrigated spring wheat production in northern Xinjiang province was obtained: initial canopy cover is 6.65%,maximum canopy cover is 90%,time from sowing to emergence is 101?·d,time from sowing to flowering is 815?·d,length of the flowering stage is 169?·d,time from sowing to maturity is 1910?·d,water productivity normalized for ET0 and CO2 is 18.0 kg/m3,reference harvest index is 42.0%,crop coefficient when canopy is complete but prior to senescence is 1.20.2.The model can accurately simulate the evapotranspiration of drip irrigated spring wheat in this region after calibration.Based on that,the simulated water content in 0.6m soil profile,canopy cover,aboveground dry biomass and grain yield also achieved a good simulation accuracy,the corresponding R2 and RMSE is 0.40,14.34mm;0.88,6.84%;0.96,0.78t/hm2,respectively.3.The simulation of net irrigation requirement for drip irrigated spring wheat showed that: the net amount of irrigation in wet year(2009),normal year(2011),and dry year(2014)is 123,148,197 mm,respectively;the growing period of spring wheat sown on March 21,March 31,and April 10 is 100,98,94 days,respectively;the average leaf expansion water stress when the threshold of root zone depletion is 50%,70%,90% RAW is 7%,28%,36%,respectively;the water drained out of the soil profile when soil texture is sand,loam,silt is 310,28,0mm,respectively;the water moved upward by capillary rise when the groundwater level is 3,5,7m is 156,23,0mm,respectively;when the initial water content in soil profile is 60%,80%,100% TAW,the water moved upward by capillary rise is 208,178,156 mm,and the net amount of irrigation is 220,176,123 mm,respectively.4.The simulation of irrigation regime of drip irrigated spring wheat showed that: with the increase of irrigation quota and irrigation frequency,transpiration,biomass and yield of drip irrigated spring wheat was increasd;While drip irrigation frequency has no obvious influence on harvest index and water use efficiency of spring wheat.The water use efficiency of drip irrigated spring wheat yield was mainly affected by rainfall year type.[Conclusion]It is feasible to apply the localized AquaCrop model to simulation of evapotranspiration of drip irrigated spring wheat,and precision irrigation guidance in arid area;the feature of simulating the net irrigation water requirement in AquaCrop model has the capability to meet the water needs of crops under various environmental conditions;the annual precipitation type significantly influence the net irrigation requirement of spring wheat,the sowing date significantly influence the growing period of spring wheat,the threshold of root zone depletion significantly influence the average leaf expansion water stress of spring wheat,the soil texture significantly influence the water drained out of the soil profile,the groundwater level significantly influence the water moved upward by capillary rise,the initial water content in soil profile significantly influence the water moved upward by capillary rise and the net irrigation requirement of spring wheat.The best irrigation regime in wet year(2009),normal year(2011),dry year(2014)was D2W2,D2W3,D3W3,respectively.