1. ETH Zurich, Institute of Agricultural Sciences , Universitätstrasse 2, 8092 Zurich , Switzerland
2. Agroscope, Earth Observation of Agroecosystems Team, Division Agroecology and Environment , Reckenholzstrasse 191, 8046 Zurich , Switzerland
3. University of Hohenheim, Institute for Crop Science, Biostatistics Unit , Fruwirthstrasse 23, D-70593 Stuttgart , Germany
4. Wageningen University and Research, Biometris , PO Box 16, 6700 AA Wageningen , The Netherlands