1. Former PhD student at São Paulo State Univ. (UNESP)College of Agricultural SciencesBotucatu, São PauloBrazil
2. Univ. of Minnesota, Dep. of Soil, Water, and Climate1991 Upper Buford CircleSt. PaulMN55108
3. São Paulo State Univ. (UNESP), College of Agricultural SciencesDep. of Crop ScienceLageado Experimental Farm, P.O. Box 23718610‐034Botucatu, São PauloBrazil
4. São Paulo State Univ. (UNESP)Center of Tropical Roots and Starches (CERAT)Lageado Experimental Farm, P.O. Box 23718610‐034Botucatu, São PauloBrazil
5. Univ. of MinnesotaDep. of Soil, Water, and Climate1991 Upper Buford CircleSt. PaulMN55108