1. Field Crops Research Institute, Hai Duong and Hanoi University of Agriculture, Gia Lam, Hanoi, Viet Nam
2. Applied Plant Research, Wageningen University and Research Centre, P.O. Box 430, 8200 AK Lelystad, The Netherlands
3. Plant Research International, Wageningen University and Research Centre, Wageningen, The Netherlands
4. Centre for Crop Systems Analysis, Wageningen University, Wageningen, The Netherlands