1. Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843-2474, USA
2. Conselho Nacional do Desenvolvimento Científico e Tecnológico (CNPq), 70750-901 Brasília, DF, Brazil
3. Texas AgriLife Research, David Wintermann Rice Research Center, Eagle Lake, TX 77434, USA
4. BASF Corporation, Agricultural Products Division, 6583 Main Street, Winnsboro, LA 71295, USA