[1] Hokkaido Univ, Grad Sch Agr, Kita Ku, Sapporo, Hokkaido 0608589, Japan
[2] Natl Inst Crop Sci, Tsukuba, Ibaraki, Japan
[3] Japan Int Res Ctr Agr Sci, Tsukuba, Ibaraki, Japan
[4] Int Rice Res Inst, Manila, Philippines
[5] Hokkaido Univ, CRIS, Sapporo, Hokkaido 0608589, Japan