1. SETREM–Sociedade Educacional Três de Maio, Três de Maio 98910-000, Brazil
2. Department of Economics and International Relations–DERI, Faculty of Economics–FCE, Interdisciplinary Center for Research and Studies in Agribusiness–CEPAN, Bioeconomics Research Group, Universidade Federal do Rio Grande do Sul–UFRGS, Porto Alegre 90040-000, Brazil