Study On Wheat Crop Coefficient And Irrigation Schedule Optimization Of Drip Irrigation In Yili River Irrigation Area

Object:The south bank of the Ili River is a newly reclaimed irrigation area with problems such as irrational water use and damage to drip irrigation belts caused by wind during the planting season.This thesis investigates the effects of mulching depth and drip irrigation amount on the growth,physiology and yield of drip irrigated wheat.This thesis investigates the effects of mulching depth and drip irrigation on the soil moisture dynamics,water consumption characteristics and crop coefficient Kc values at each stage of wheat fertility.The optimal irrigation interval was determined by establishing a water production function model and a quadratic function model of yield and evapotranspiration for the whole fertility period.The optimum irrigation system for drip irrigated wheat at different mulching depths was developed to provide a theoretical basis for the promotion of shallow mulched drip irrigation technology.Methods:Field trials will be conducted in 2020-2021 at the joint experiment station of the management station of the south bank of the Ili River irrigation area of the fourth division of the Xinjiang production and construction corps and Shihezi University,China.In 2020,"Ningchun 16"will be used in the trial area,and in 2021,"New Winter 41"will be used as the trial area.A completely randomized combinatorial design experiment was used to set two factors,mulch depth and drip irrigation amount.The depth of the cover soil was 0 cm(D0),5 cm(D5),and 10 cm(D10).The drip irrigation levels were 270 mm(W1),315 mm(W2),360 mm(W3),and 405 mm(W4).Though drip irrigation amount W4 was a new treatment in 2021,and each treatment was repeated three times.The actual irrigation of the field in the experimental area was used as a control group of 450 mm(CK).Irrigation was applied eight times throughout the fertility stage,with fertilizer entering with the water.Results:(1)At the same soil cover depth,the height and leaf area of wheat plants show a parabolic pattern of variation with the fertility process,and the leaf area reaches its peak at the tassel stage.The ratio of dry matter distribution among leaves,stems and ears at maturity was 1:2:4.The trend of wheat plant height and leaf area index increasing and then decreasing with increasing drip irrigation in both seasons.From jointing stage to 20 d after flowering,flag leaf chlorophyll SPAD values showed a"decreasing-increasing-decreasing"trend,with the maximum values in each drip irrigation treatment at the flowering stage.The SPAD values,net photosynthetic rate,transpiration rate and stomatal conductance of the flag leaf showed an increasing and then decreasing trend with increasing drip irrigation,and were all maximum in the W3 treatment.The original initial light energy conversion rate,PSII potential activity and photochemical burst coefficient values of wheat flag leaves increased with increasing mulch depth and then decreased with increasing drip irrigation,and the mulch treatment was significantly higher than the surface drip irrigation treatment.The effective number of harvested ears,1000-grain weight and yield of wheat were significantly affected by the mulch depth and drip irrigation amount.The effective number of harvested ears,grain size,1000-grain weight and seed yield of drip irrigated wheat tended to increase and then decrease with increasing drip irrigation amount,with the maximum in the W3 treatment.The optimum wheat yield for both years was reached at 360 mm(W3D5),with seed yields of 6829.32 kg/hm~2(2020)and 9315.50 kg/hm~2(2021).(2)Shallowly buried drip irrigation increases soil moisture in the 20-40 cm soil layer,and the change in soil moisture content in the 40-60 cm soil layer is relatively stable,which is a stable water absorption layer for wheat.The mulch shallowly buried drip irrigation can increase the width of the wetting layer after irrigation,but the width of the wetting layer gradually becomes narrower with increasing distance in the horizontal direction.(3)In 2020(Ningchun 16),water consumption of wheat with shallow mulch drip irrigation was mainly concentrated in the heading and jointing stages.The daily water consumption at the heading stage ranged from 4.25-7.00 mm/d,with a modulus of 29.35%-35.04%,and at the jointing stage ranged from 5.52-10.39mm/d,with a modulus of 14.54%-17.40%.In 2021(New Winter 41),water consumption during the fertility of wheat with shallow drip irrigation was mainly concentrated in the grouting and jointing stages.The daily water consumption was 5.13-6.41 mm/d with a modulus of 25.56%-30.71%at the grouting stage,2.20-3.62mm/d with a modulus of 23.99%-25.52%at the jointing stage and 3.97-5.41 mm/d with a modulus of 16.88%-19.04%at the heading stage.(4)The crop coefficient of high-yield wheat field in the irrigation area on the South Bank of Yili River,"Ningchun 16",seedling stage(0.57),tillering(0.83),jointing(1.50),heading(1.02),grouting(0.80)and maturity(0.77)."Xindong 41",seedling stage(0.64),tillering(0.87),overwintering(0.59),rejuvenation(0.78),jointing(0.88),heading(1.00),grouting(1.17)and maturity(0.81).(5)A water production function was established by using wheat yield and irrigation quota and yield and evapotranspiration to determine the appropriate irrigation quota interval for the test year.2020(Ningchun 16)had an irrigation quota interval of 382 to 386 mm for drip irrigated wheat,from which an irrigation quota of384 mm was selected.2021(New Winter 41)had an optimal irrigation quota interval of 389 to 390 mm,from which an irrigation quota of 390 mm.Conclusion:The covering depth of drip pipe had the significant effects on the height,leaf area and dry matter re-accumulation and photosynthetic fluorescence parameters of drip irrigated wheat,with the highest wheat yield and water production appearing at 5 cm of covering depth.The optimum irrigation amount for drip irrigated spring wheat in the Ili River irrigation area is 384 mm,with 1,1,2,2 and 2 irrigations for seedling,tillering,jointing,heading and filling,respectively.And the single irrigation amount is 48 mm.The optimum irrigation amount for winter wheat is 390 mm,with 1,3,2 and 2 irrigations for tillering,jointing,heading and filling,respectively.And the single irrigation amount is 48.75 mm.Our study provides a theoretical basis for the application of buried drip irrigation technology in the Ili River irrigation area.