A regional implementation of WOFOST for calculating yield gaps of winter wheat across the European Union

Wheat is Europe’s dominant crop in terms of land use in the European Union (EU25). Most of this wheat area is sown in autumn, i.e., winter wheat in all EU25 countries, apart from southern Italy, southern Spain and most of Portugal, where spring wheat varieties are sown in late autumn. We evaluated the strengths and limitations of a regional implementation of the crop growth model WOFOST implemented in the Crop Growth Monitoring System (CGMS) for calculating yield gaps of autumn-sown wheat across the EU25. Normally, CGMS is used to assess growing conditions and to calculate timely and quantitative yield forecasts for the main crops in Europe. Plausibility of growth simulations by CGMS in terms of leaf area, total biomass and harvest index were evaluated and simulated yields were compared with those from other global studies. This study shows that water-limited autumn-sown wheat yields, being the most relevant benchmark for the largely rain fed wheat cultivation in Europe, are plausible for most parts of the EU25 and can be used to calculate yield gaps with some precision. In parts of southern Europe unrealistic simulated harvest index, maximum leaf area index and biomass values were found which are mainly caused by wrong values of phenology related crop parameters. Furthermore CGMS slightly underestimates potential and water-limited yields, which calls for a calibration using new field experiments with recent cultivars. Estimated yield gap is between 2 and 4 t ha-1 in main parts of the EU25, is smaller north-western Europe and highest in Portugal