Affiliation: | (1) Research Institute of Seed Production, 6–6-3, Minamiyoshinari, Aoba-ku, Sendai, 989–3204 Japan e-mail: hatake@tree.or.jp Tel. +81–22–279–4731; Fax +81–22–279–4755, JP;(2) Faculty of Agriculture, Tohoku University, Aoba-ku, Sendai, 981–8555, Japan, JP |