Determining the Most Suitable Depth of Irrigation Water of Wheat Plant Usingthe AquaCrop Model in Order to Increase Water Use Efficiency

The growth of agronomic plants has a complex process and involves several factors. In field condition, considering the different irrigation scenarios are time-consuming and costly so, the use of models after calibration and validation makes it possible to simulate yield and water use efficiency with acceptable accuracy. This research was carried out in Hamidyeh- Khouzestan region in two years from 2014 to 2016. The results of first year were used for calibration and the results of the second year were used for validation the model. The results showed that with considering the conventional irrigation intervals in the area (4 to 5 irrigation intervals for wheat cultivation) and the depth of application of irrigation water varying from 100 to 120 millimeters, it is possible to increase wheat grain yield by 30 percent and reduce water consumption by about 46 percent than farmer's usual conditions. The water use efficiency of wheat in conventional condition in that region is about 0.32 kg of grain yield per cubic meter of water consumption. This value can be increased by applying irrigation management based on the depth of applied water consumption in the range of 100-120 mm in the amount of 0.78 kg of grain yield per cubic meter. Validation of the AquaCrop model showed that the AquaCrop model in wheat grain yield and water use efficiency simulation, respectively, had a 5 and 13 percent error. Therefore, it can be concluded that this model has the proper performance and accuracy for simulation wheat yield and water use efficiency.