1. Instituto Nacional de Investigaciones Agropecuarias (INIAP) Estaciόn Experimental Santa Catalina Panamericana Sur km 1 Quito Ecuador
2. USDA ARS 2150 Centre Ave. Fort Collins CO 80526 USA
3. Dep. of Agricultural and Applied Economics Virginia Polytechnic Institute and State Univ Blacksburg VA 24061 USA