Evaluation of the efficiency of APSIM-Wheat model for simulation of phenology and grain yield of bread wheat (Triticum aestivum L.) in drylands of west and northwest of Iran

Crop simulation models are valuable tools for prediction of crop performance under various weather conditions and allow designing methods to limit the negative impacts of adverse environmental constraints. Agricultural Production Systems sIMulator (APSIM) is a comprehensive model that simulates the performance of a wide range of crops in response to climatic, soil and management factors. In this study, the performance of APSIM-Wheat model in simulating dryland wheat phenology and grain yield was evaluated for the first time in the dryland wheat belt of west and northwest of Iran. Model calibration and evaluation was performed using information of 91 experiments from 11 research field stations in five western and northwestern provinces of Iran from 2001 to 2016. Results showed that the mean observed and simulated days to flowering and physiological maturity were 215 and 218, and 252 and 252 days after sowing (DAS), respectively. These were further supported by an acceptable range of statistical indices of nRMSE (0.29 and 0.16%), CRM (-0.018 and 0.002) and D-index (0.091 and 0.013), for flowering and physiological maturity, respectively. The observed and the simulated mean grain yield were 2245 and 2249 kg.ha-1, respectively. The values of nRMSE (7.21%), CRM (-0.002) and D-index (0.037) showed that APSIM-Wheat performed quite satisfactorily and could be considered in planning to increase dryland wheat production in west and northwest of Iran. The overall results of this study showed that the APSIM-Wheat model can be used to determine the best crop management practices, yield gap analysis, climate change impact assessment and climate change adaptation strategies in dryland wheat fields in western and northwestern of Iran.