1. Department of Forage Plants and Agrometeorology, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
2. Department of Plant Sciences, University of California, Davis, Davis, CA
3. Department of Soil Science, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
4. Department of Plant Science and Phytosanitation, Federal University of Paraná, Curitiba, PR, Brazil