1. Russell Research Center, USDA-ARS, P.O. Box 5677, Athens, Georgia 30604; Pee Dee Research and Education Center, Clemson University, Florence, South Carolina 29501; Chemistry Department, University of Georgia, Athens, Georgia 30602; Department of Crop Science, North Carolina State University, P.O. Box 1555, Oxford, North Carolina 27565; and U.S. Vegetable Laboratory, USDA-ARS, 2875 Savannah Highway, Charleston, South Carolina 29414