1. Dep. of Genetics; Univ. of Stellenbosch; Private Bag X1 Matieland 7602 South Africa
2. Cereal Research Centre; Agriculture and Agri-food Canada; 195 Dafoe Road R3T 2M9 Winnipeg MB Canada
3. Dep. of Plant Sciences; Univ. of the Free State; PO Box 339 Bloemfontein 9300 South Africa