Study On The Deficit Irrigation Of Winter Wheat Based On Jensen’s Model

The increasing shortage of water resources is the main limiting factor of agriculture inarid areas. In response to the contradiction between water stress and high crop yield, it is aneed for deficit irrigation. The deficit irrigation experimental of winter wheat was carried outin the experimental field which mainly through controls the designed limit of soil moisture indifferent growth stage. Through the observation of yield and agronomic traits, irrigationquantity and the variable quantity, we calibrated Jensen model. The relationship betweenwinter wheat yield and water consumption can be determined, then the critical stages of waterdeficit can be identified, so that we can ensure the use of water in the critical stages in thecase of water shortage and work out the optimized irrigation system, which can provideguidance for the deficit Irrigation of winter wheat in Tianjin. The he main conclusion obtainedin this paper:1. Stage of crop water requirement, water requirement rate and water consumption ineach treatment are quite different due to different growth stages duration and climaticconditions. the amount of daily water consumption is very small before returning green stage,and increasing as the time going, enters the rapid increasing after jointing stage until headingstage during which the amount gets maximum, and then getting decrease during maturitystage but the water consumption is also keeping a large amount, what mainly because of hightemperature and the strong light intensity which resulting in larger evapotranspiration; Wateruse efficiency is not the highest yield point or the least water using point.2. Discussing the effects of different irrigation treatments on yield using Jensen Model.Through multiple correlation coefficient test method to verify the correctness of the Jensenmodel. The result shows that winter wheat’s key water requirement periods are heading,filling and jointing stage while green stage and maturity are less sensitive to water. Under thecondition of water deficit, it should be ensured to supply on heading, filling and jointing stagefirstly, because appropriate water stress on the green stage and maturity does not cause a greatimpact on the yield.3. Use the Jensen models’ formal structure for the purpose of estimating the relationshipbetween water consumption and agronomic traits.①Panicle weight is most sensitive to waterat heading and filling stages.②Irrigation during heading stage can significantly improve The grain number per spike of winter wheat.③Irrigation during filling stage and heading stagecan significantly increase thousand grain weight of winter wheat.④Water consumption ofmaturity has little impact on panicle weight.⑤Irrigating during mature would have a negativeeffect compensation to grain weight.⑥Winter wheat enters the rapid growth stage afterreturning green stage, height and leaf area are increasing, and then they get into jointing andheading stages which are the rapid growth period. The leaf area gets largest in heading stagewhile plant height continues to grow until stable in grain filling stage. But leaf area hasdeclined during filling stage while rapidly decreases with aging leaf area in mature stage⑦thedeficit irrigation has slight influenced of the height and leaf area because of the short durationof deficit irrigation and compensation effect after rehydration, but continuous water stress hasgreat influence on height and leaf area.4. Jensen is a very good model to predict yield, which can truly reflect the function ofwater consumption and the final production. Jensen model structure used in the agronomictraits had certain regularity, but the precision is not high. So the next study could beconsidered to optimize or deform the Jensen model structure to seeking relationship betweenagronomic traits and water consumption.5. Determine the optimal irrigation system by resulting water production function’sJensen model. Using Crop water production function’s Jensen models as an objective functionand using available water and soil moisture as the constraints, carrying out an optimizationcalculation, then the optimization of irrigation system is obtained which is high crop yield andcan save water under different water supply in Tianjin area.