1. Centre for Crop Systems Analysis, Wageningen University, 6700 AK, Wageningen, The Netherlands
2. Horticulture and Product Physiology, Wageningen University, 6700 AA, Wageningen, The Netherlands
3. Biometris, Mathematical and Statistical Methods Group, Wageningen University, 6700 AA, Wageningen, The Netherlands
4. Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48823