1. Agriculture and Agri‐Food Canada Harrow ON N0R 1G0 Canada
2. Agriculture and Agri‐Food Canada Fredericton NB E3B 4Z7 Canada
3. Dep. of Crop and Soil Sciences North Carolina State Univ. Raleigh NC 27695‐7620 USA
4. Dep. of Chemical and Biochemical Engineering Western Univ. London ON N6A 5B9 Canada