1. Dep. of Agronomy and Plant Genetics; Univ. of Minnesota; 1991 Upper Buford Cir., 411 Borlaug Hall St. Paul MN 55108
2. Dep. of Crop, Soil, and Environmental Sciences; Univ. of Arkansas; 1366 W. Altheimer Dr. Fayetteville AR 72704
3. USDA-ARS; 3127 Ligon St. Raleigh NC 27607
4. Dep. of Plant and Soil Science.; Oklahoma State Univ.; 368 Agricultural Hall Stillwater OK 74078