○Keitaro Hirose¹, Yuhei Yajima², Isamu Nakamura³, Atsushi Toyoda^1,2 (1. Col of Agr, Ibaraki Univ, Ibaraki, Japan, 2. United Grad Sch of Agr Sci, Tokyo Univ of Agri and Tech, Tokyo, Japan, 3. Ctr for Med Sci, Ibaraki Pref Univ of Health Sci, Ibaraki, Japan)