1. Bayer Crop Science, Coxilha 99145-000, RS, Brazil
2. Department of Agronomy, Iowa State University, Ames, IA 50011, USA
3. Department of Agronomy, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand
4. Department of Statistics, Iowa State University, Ames, IA 50011, USA