1. School of Agriculture and Enterprise Development, Department of Agricultural Science and Technology, Kenyatta University, Nairobi, Kenya;
2. College of Agriculture and Veterinary Sciences, Department of Land Resource Management and Agricultural Technology, University of Nairobi, Nairobi, Kenya;
3. CGIAR Research Program on Roots, Tubers and Bananas (RTB), International Potato Center, Sub-Saharan Africa Regional Office, ILRI Campus, Nairobi, Kenya;
4. School of life Sciences, University of Applied Science Bingen (TH Bingen), Bingen, Germany