1 Kenya Agricultural Research Institute, National Horticultural Research Center, P. O. Box 01000 220, Thika. 2 Department of Botany, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 00200-62000, Nairobi. 3 Department of Horticulture, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 00200-62000, Nairobi. 4 Kenya Agricultural Research Institute, Biotechnology Cen...