1. Department of Agronomy, Bayero University, Kano, Nigeria
2. Department of Plant Sciences, Faculty of Agriculture, Ahmadu Bello University, Zaria, Nigeria
3. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Kano, Nigeria
4. Centre for Dryland Agriculture, Bayero University, Kano, Nigeria
5. Department of Horticulture and Crop Science, The Ohio State University, Wooster, OH, USA