calibration and evaluation of the ceres-maize model in gorgan climatic conditions

sowing date and irrigation are two constrain factors for maize production. these factors can be simulated by using ceres-maize model. for this purpose two experiments (each one at two years) were carried out at agricultural research station of gorgan which is golestan province capital. the model was calibrated using three treatments of optimum irrigation and without stress in 2012 and two treatment of the second experiment in 2007. evaluation was done using planting date treatment (2008), planting date and deficit irrigation in 2012 and 2013. the results of evaluation of the model indicated that the model simulated phonological stages (anthesis day and maturity day) with high accuracy in different sowing date and different irrigation regimes. the values of root mean square for anthesis and maturity dates were 2.5, 2.9 days respectively. therefore this model can be used in field programing management. also the results of evaluation in spring sowing date (2008) and summer sowing date (2012 and 2013) indicated that the model simulated dry matter and yield of maize with high accuracy. on the other hand, the model simulated trend of reduction of dry matter and leaf area index (lai) in different levels of irrigation but hadn’t enough accuracy in terms of model statistical indices. referring to results of this experiment this model can be used in gorgan climatic conditions for simulation of growing stages and grain yield of maize under favorable conditions.