1. Dep. of Plant Science; Nova Scotia Agricultural College; P.O. Box 550 Truro NS B2N 5E3 Canada
2. Dep. of Plant Sciences; Univ. of Saskatchewan; Saskatoon SK S7N 0W0 Canada
3. Atlantic Food and Horticulture Research Centre; Agric. and Agri-Food Canada; 32 Main Street Kentville NS B4N 1J5 Canada
4. SCPFRC; Agric. and Agri-Food Canada, 43 McGilvray St.; Univ. of Guelph; Guelph ON N1G 2W1 Canada