1. Dep. of Crop Science; Univ. of Zimbabwe; PO Box MP 167 Mt. Pleasant Harare Zimbabwe
2. School of Agricultural; Earth and Environmental Sciences; Univ. of KwaZulu-Natal; Private Bag X01 Scottsville 3209 South Africa
3. Global Maize Program; International Maize and Wheat Improvement Centre (CIMMYT); PO Box MP 163 Mt. Pleasant Harare Zimbabwe