1. Kansai Regional Breeding Office, Forest Tree Breeding Center, Forestry and Forest Products Research Institute, 1043 Uetsukinaka, Shoo, Katsuta, Okayama 709-4335, Japan
2. Department of Forest Science, Faculty of Agriculture, Utsunomiya University, 350 Mine-machi, Utsunomiya, Tochigi 321-8505, Japan
3. Department of Forest Environmental Science, Faculty of Agriculture, Kyushu University, 6– 10–1Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
4. Research Division, The University Forests, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1– 1–1Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan