1. Department of Agricultural Economics, Obafemi Awolowo University, Ife, Nigeria
2. Department of Agricultural Economics, Ahmadu Bello University, Zaria, Nigeria
3. International Crop Research Institute for the Semi-Arid Tropics, Kano, Nigeria
4. Center for Dryland Agriculture, Bayero University, Kano, Nigeria
5. International Maize and Wheat Improvement Centre, Nairobi, Kenya