1. Centro de Investigaciones Agrarias de Mabegondo Apartado 10 A Coruña Spain
2. Biometrics and Statistics UnitInternational Maize and Wheat Improvement Center (CIMMYT) Apdo. Postal 6‐641 06600 Mexico DF Mexico
3. Dep. of Agronomy and Dep. of StatisticsUniv. of Kentucky Lexington KY 40546‐0091