1. Dep. of Biological Sciences Federal Univ. of Paraná (UFPR) Curitiba Paraná Brazil
2. Dep. of Rural Engineering and Exact Sciences, School of Agricultural and Veterinarian Sciences São Paulo State Univ. (Unesp) Jaboticabal São Paulo Brazil
3. Univ. of São Paulo, College of Agriculture “Luiz de Queiroz”, Soil Science and Plant Nutrition Dep. Piracicaba SP Brazil
4. Brazilian Agricultural Research Corporation (EMBRAPA SOJA) Londrina Paraná Brazil