1. National Institute of Agricultural and Livestock Researches (INIAP-Ecuador), Santa Catalina Experimental Station, Quito, Ecuador; and Colegio de Postgraduados (CP), Campus Montecillo, Montecillo, Texcoco 56230, State of México, México
2. Campo Experimental Valle de México INIFAP, 56230 Chapingo, State of México, México
3. International Maize and Wheat Improvement Center (CIMMYT), 56237 México, DF, México
4. Colegio de Postgraduados (CP), Campus Montecillo, Montecillo, Texcoco 56230, State of México, México