An improved version of WOFOST for the simulation of quantitative and qualitative aspects of winter rapeseed production

Rapeseed (Brassica napus L.) is one of the most widespread oleaginous crop. Its importance is expected to increase in Europe in the coming years, since the Renewable Energy Directive set for EU Countries the goal of supplying the 10% of transport fuel with renewable sources in 2020 (OECD-FAO, 2011). This aim will likely encourage the cultivation of rapeseed, the most important oilseed crop in Europe for biodiesel production. In this context, crop models can be effective tools in supporting the bioenergy sector, since they can be used to identify the most suitable lands for the cultivation of a specific crop, to optimize the agro-management and to forecast quantitative and qualitative aspect of productions. WOFOST (van Keulen and Wolf, 1986) is a widely used generic crop model appreciated for the high level of detail used to reproduce crop growth and development. On the other hand, it is characterized by a large number of parameters, in turn leading to time consuming parameterization procedures. Moreover, a large part of these parameters are organized in AFGEN (Arbitrary Function GENerator) tables which describe the dependence of parameters on air temperature or development stage. Given their high flexibility, these tables could allow the user to fit unrealistic functions to describe plant processes. Finally WOFOST – being a generic model – is not able to reproduce the specific processes characterizing some crops, especially rapeseed. In order to overcome these limitations, we formalized a specific crop model (i.e., WOFOST_Rapeseed) by improving and extending the original version of the model. The development of the new model targeted (i) the reduction of model complexity via the use of crop-specific functions driven by few parameters with a biophysical meaning to eliminate AFGEN tables, (ii) the improvement of leaf area dynamics within the vertical profile of the canopy and (iii) the implementation of approaches for yield quality. An improved version of WOFOST for the simulation of quantitative and qualitative aspects of winter rapeseed production.