Visiting Professor. Permanent address: Agronomy Division, Korean Ginseng and Tobacco Research Institute, P.O. Box 59, Suweon, Korea.
Received for publication 9 Aug. 1984. This research was supported by Operating Grant No. A6697 of the Nat. Sci. and Eng. Res. Council of Canada held by John T.A. Proctor, and by the Korean Sci. Foundation. We are indebted to R.J. O'Hara Hines, and O.B. Allen, Dept. of Mathematics and Statistics, Univ. of Guelph, for advice and discussions on the statistical analyses, and to Dean Louttit for technical assistance. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.