Received for publication 13 Apr. 1987. Salaries and research support provided by State and Federal funds appropriated to the Ohio Agr. Res. and Dev. Center, The Ohio State Univ., and Ohio Fresh Market and Processing Vegetable Research Foundation. Journal article no. 59–87. 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.