1. The CGIAR Research Program on Roots, Tubers and Bananas (RTB), International Potato Center, Sub-Saharan African Regional Office, P.O Box, 25171-00603, Nairobi, Kenya
2. Agricultural Technology, University of Nairobi, P.O. Box, 29053-00625, Nairobi, Kenya
3. Department of Crop Sciences, Plant Nutrition and Yield Physiology, University of Gottingen, Carl-Sprengel-Weg 1, 37075. Gottingen, Germany
4. School of Agriculture and Enterprise Development, Department of Agricultural Science and Technology, Kenyatta University, P.O Box, 43844 −00100, Nairobi, Kenya
5. School of Life Sciences, University of Applied Science Bingen (TH Bingen) Berlinstrasse 109, 55411, Bingen, Germany