Parameterization and Evaluation of a Simple Simulation Model (SSM-iCrop2) for Potato ( Solanum tuberosum L.) Growth and Yield in Iran


Crop models can be used to estimate yield, water requirements and plant nutrition requirements under different conditions. This study examines the performance of the SSM-iCrop2 model in terms of predicting tuber yield, phenological stage and water requirement of potato (Solanum tuberosum L.) under changing climate circumstances in Iran. Simulation of potato growth, tuber yield and water requirement for cultivars commonly grown in Iran (Agria, Marfona, Sante and Arinda) was performed using the SSM-iCrop2 model. Data from different field experiments in major potato-producing provinces were used for parameterization and evaluation. The parameterization results of the SSM-iCrop2 model showed that two maturity groups (early and late maturity) were determined with thermal units of 1100 and 1500 °C day−1, respectively, in the important potato-producing provinces. The model was evaluated based on independent experimental data which were not used for parameterization step. The observed tuber yield and water requirement ranged between 2013 and 5902 g m−2 and 3523 and 8547 m3 ha−1 with an average of 3542 g m−2 and 6178 m3 ha−1, respectively. The simulated tuber yield and water requirement varied in the range of 2489 to 5881 g m−2 and 2200 to 7149 m3 ha−1 with an average of 3607 g m−2 and 5901 m3 ha−1, respectively. Also, the evaluation results indicated that the correlation coefficient (r), root mean square error (RMSE) and coefficient of variation (CV) for the simulated versus observed tuber yield and water requirement were 0.80, 543 g m−2 and 14% and 0.85, 944 m3 ha−1 and 15%, respectively. Therefore, the model can be used to estimate potential tuber yield, yield gap and the effects of climate change.