Experiment Of Deficit Irrigation Of Forage Crop And Study On Crop-Water Model And Optimizing Decision For Water Management

In recent years, because of lack of water, it cannot assurance normal irrigation, and waste of water is prevalent, therefore irrigation efficiency of the most of irrigation project and irrigation districts is low. Base on above, this paper studies on three kinds of forage crop (Lucerne, silage corn and feed corn) under deficit irrigation in Maowusu desert. Under the different duty, study forage crop sensitive response to water stress; sensitive level in different growing stage; influence of water to physiological indexing and yield. According to the analysis, the model of crop response to soil water of forage crop is confirmed, and we gain the multiple objective irrigation program and optimal management decision. It offers the technical support for livestock production and the sustained development of environment in west north. The main conclusions are below: (1) Analyzing the influence of soil water stress to yield and physiological status (plant height, LAI, leaf water potential and transpiration speed). According to the analysis of leaf water potential and transpiration speed of Lucerne and silage corn in different growing stage and different soil content, find the relationship with environmental factor (temperature, net radiation, saturation deficiency and water content), and establish the quantum relation of leaf water potential, transpiration speed and environmental factor. Besides establishing the dry matter content model base on the study of the component of Lucerne. The incoming PAR and transmission PAR are maximal at noon in sunny day. The linear relation between absorption proportion of radiation and LAI (leaf area index) is fine from bolter branch period until mature period. (2) According to the analysis of the deficit irrigation experiment data, establish the quantum relation between yield and moisture content of whole growing season, moisture content of growing stage. From the result of comparison, to Lucerne, Stewart model can disclosure the numerical relation between yield and water, the most sensitive to water is from squaring stage to florescence; to silage corn, Jensen model disclosure the numerical relation between yield and water, the most sensitive stage to water is from jointing stage to heading stage. At the meantime, establishing the BP neutral network model of Lucerne, it can reflect the numerical relation between yield and water perfectly, and it has high precision. (3) According to water requirement data, analyze soil water content dynamic regulation and water requirement regulation of Lucerne, silage corn and feed corn, and establish insufficient irrigation program. Water need peak value of Lucerne is from the last ten-day of June to the last ten-day of August; peak value of silage corn and feed corn is from the last ten-day of July to the first ten-day of August, its water need intensity of day alter greatly, the minimum value is 1.3mm/d, the peak value is 11.5mm/d. The soil water content dynamic condition influenced by precipitation, irrigation and embedded depth of groungwater. (4) Based on the dynamic programming, we establish insufficient irrigation program: to Lucerne, when the irrigation water is less, water need of squaring stage must be satisfied first; to silage corn, when M≤100m3/mu,water need of jointing stage to heading stage must be satisfied first, if the irrigation water is sufficient, it should irrigate twice. The achievement of this paper provides reference for later deficit irrigation experiment of forage crop.