1. Department of Controlled Agriculture, Kangwon National University, Chuncheon, 201-701, Korea
2. Department of Environmental Horticulutre, The University of Seoul, Seoul, 130-743, Korea
3. Protected Horticulture Experiment Station, NHRI, RDA, Hanan, 618-800, Korea
4. Department of Agricultural Sciences, Korea National Open University, Seoul, 110-791, Korea
5. Department of Horticulture, Kangwon National University, Chuncheon, 200-701, Korea