Evaluation and comparison of aquacrop and FAO models for yield prediction of winter wheat under environmental stresses

In this research, two agro-hydrological models: AquaCrop and FAO were evaluated and compared to predict of winter wheat grain yield under water and salt environmental stresses. A field experimental was conducted under factorial split plot design with three salinity levels of irrigation water include: S1, S2 and S3 corresponding to 1.4, 4.5 and 9.6 dS/m and four irrigation levels include: I1, I2, I3 and I4 corresponding to 50, 75, 100 and 125% of crop water requirement based on the FAO Penman-Monteith method. Experimental was conducted for two varieties of winter wheat: Roshan and Ghods, with three replications in an experimental field of Birjand University during 2005-2006. Based on results, the average mean relative error (MRE) of the AquaCrop and FAO models in grain yield prediction for Roshan were obtained 2.96 and 9.20%, respectively and for Ghods were obtained 6.79 and 26.11%, respectively. The average normalized root mean square error (NRMSE) of the AquaCrop and FAO models were calculated 3.44 and 9.94% for Roshan and 6.02 and 22.10% for Ghods, respectively. The AquaCrop model predicted yield prediction with an appropriate precision in entire range of water and salt Stresses. The FAO model in grain yield prediction of winter wheat showed significant error under high water stress (S1I1, S2I1 and