1. Panhandle Res. & Ext. Ctr., Univ. of Nebraska 4502 Avenue I Scottsbluff NE 69361‐4939
2. Plant Sci. Res. Unit, USDA‐ARS, U.S. Dairy Forage Res. Ctr. (Minnesota Cluster), and Dep. of Soil, Water, and Climate 439 Borlaug Hall, Univ. of Minnesota St. Paul MN 55108‐6028
3. Plant Sci. Res. Unit, USDA‐ARS, and Dep. of Agronomy and Plant Genetics 411 Borlaug Hall, Univ. of Minnesota St. Paul MN 55108‐6028