1. Alberta Agriculture and Rural Development, Dep. of Agricultural, Food, and Nutritional Sci. Univ. of Alberta Edmonton AB T6G 2P5
2. Dep. of Agronomy Univ. of Wisconsin Madison WI 53706
3. Dep. of Plant Sci. Univ. of Manitoba Winnipeg MB R3T 2N2
4. Dep. of Plant Agriculture Univ. of Guelph Guelph ON N1G 2W1