Estimation of Potential Yield of Grain Maize in Mahidasht, Kermanshah Using WOFOST, a Crop Growth Simulation Model



WOFOST is a crop growth simulation model which can simulate crop growth and yield components of annual crops dynamically in the various stages of growth period. Some parts of the model outputs (crop yield and crop water requirements) can be used in irrigation planning and management of water resources. In this study, a field research was carried out in a randomized complete block design with three irrigation treatments (Fully Irrigation, 20% and 40% deficit irrigation) in the research farm of Jihad-e-Agriculture and Natural Resources Research Center, located in Mahidasht, Kermanshah. The grain maize (variety 704C) was cultivated in the May 2010. The required phenological stages (emergence, flowering and maturity) for the crop growth model were observed in the field and then thermal time (degree days) required for each of the phenological stages were calculated based on daily weather data. Dry weights of leaf, stem and storage organ as well as LAI were measured eight times during the growing season. The crop parameters of the model were calibrated based on the measured data. The model outputs in the potential situation were compared with the measured data using statistical indicators including the root mean square error (RMSE), coefficient of efficiency (E), index of agreement (d), the maximum error (ME) and the coefficient of residual mass (CRM). The value of these indices were 1174, 0.96, 0.99, 16.67 & -0.02, respectively, for total biomass at the harvest time.