Study On Winter Wheat Irrigation Decision-Making By Using Crop Simulation Model Under Limited Irrigation

Based on the data from field experiment, CERES-Wheat 2.0 model was selected to study its potential application in field water management and irrigation decision-making in winter wheat under limited irrigation in Hebei province. Weather data, soil data, cultivar genetic coefficients and crop management was inputted to run the model. The main purpose of this paper was to daily simulate growth and development, yield formation, soil moisture, plant transpiration and soil evaporation of winter wheat under limited irrigation and predicted water status of plant and soil in time to aid water management and irrigation in irrigation date and irrigation amount.CERES-Wheat model was sensitive to irrigation level and performed well in reflecting the impact of irrigation level on wheat growth and development. In this paper, CERES-Wheat model was run to simulate leaf area index, aboveground biomass, stems per square meter, phenology and growth duration of winter wheat under water-limited condition and the simulated data was compared with the observed data. The simulation results indicated that CERES-Wheat model underestimated leaf area index and aboveground biomass of wheat under water stress and the difference between simulated and observed value was relatively significant.CERES-Wheat model performed well in simulating stems per square meter of wheat under different irrigation level and the result was accurate. The model can accurately predict wheat phenology and growth duration under full irrigation. However, the model cannot reflect the impact of irrigation level on growth stage because the model by itself did not account for the difference in growth stage due to water stress.The model could well reflect the response of wheat yield to irrigation level. With the irrigation amount increasing, wheat yield increased gradually, which accorded with the relationship between wheat yield and water. The model underestimated the yield under water stress and the predicted yield was lower than observed value. In order to interpret the predicted yield, we analyzed the aboveground biomass partition among leaf, stem and grain. The results suggested that CERES-Wheat model overestimated leaf weight and underestimated stem weight and grain weight, which may be helpful to explain thepredicted yield.CERES-Wheat model could daily simulate soil moisture by layer and could well reflect its response to irrigation level. Compared with observed value, the simulated soil moisture is reliable. In addition, CERES-Wheat model was run to simulate PESW (Plant Extractable Soil Water), potential evapotranspiration, crop transpiration and soil evaporation. Because of absence of measured data, the simulated values were not well evaluated. However, the simulated value could well reflect the impact of irrigation on them.CERES-Wheat model could be used to assess the impact of water stress on wheat by calculating CSD1 (cumulative water stress factor affecting photosynthesis at respective stages) and CSD2 (cumulative water stress factor affecting leaf expansion and growth at respective stages) in different growth stage. The two water stress indexes could well quantify water stress degree on different growth stage.Based on the research results, the potential application of CERES-Wheat model in wheat irrigation decision-making under limited irrigation was discussed. CERES-Wheat model performed well in assessing wheat growth and development, yield formation, dynamic predict soil water status under different irrigation treatment and determining crop water requirement and water deficit amount, which may be helpful to aid water management and irrigation decision-making. CERES-Wheat model was a useful tool to devise irrigation practice and optimize irrigation schedule.In addition, by using simulated transpiration, evaporation, evapotranspiration and PESW, WMRIs (Water management response indicators) were calculated to evaluate irrigation efficiency of different irrigation treatment. The results suggested that the impact of different water management scenarios o...