1. USDA-ARS Hard Red Spring and Durum Wheat Quality Laboratory, Harris Hall, North Dakota State University, Fargo, ND 58105. Mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.
2. Corresponding author. Phone: 701/231-8069. Fax: 701/239-1377. E-mail: doehlert@plains.nodak.edu
3. Department of Plant Sciences, Loftsgard Hall, North Dakota State University, Fargo, ND 58105.