1. School of Agriculture, Utsunomiya University, Utsunomiya, Japan
2. United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
3. Forest Tree Breeding Center, Forestry and Forest Products Research Institute, Hitachi, Japan
4. Forestry Research Institute, Chiba Prefectural Agriculture and Forestry Research Center, Sanbu, Japan
5. Faculty of Education, Chiba University, Chiba, Japan
6. Tochigi Prefectural Forestry Research Center, Utsunomiya, Japan