1. Biometrics and Statistics Unit, International Maize and Wheat Improvement Center (CIMMYT)Lisboa 27, Apdo. Postal 6‐64106600MexicoDFMexico
2. Programa de Estadistica (ISEI), Colegio de PostgraduadosMontecilloMexico
3. Biometrics and Statistics Unit, CIMMYTMexico
4. Programa de Estadistica (ISEI) Colegio de PostgraduadosMontecilloMexico
5. Maize Genetic Resources Unit, CIMMYTMexico
6. National Seed Storage Lab., USDA, ARSFort CollinsCO80523