1. Agricultural Systems Research Team Embrapa Pesca e Aquicultura Palmas TO 77008–900 Brazil
2. Agronomy Dep. Univ. of Florida Gainesville FL 32611‐0500 USA
3. North Florida Research and Education Center Univ. of Florida 3925 Hwy. 71 Marianna FL 32446 USA
4. Range Cattle Research and Education Center Univ. of Florida 3401 Experiment Station Ona FL 33865 USA
5. CIMMYT Texcoco CP, 56237 Mexico