1 National Agriculture and Food Research Organization, Kyushu Okinawa Agricultural Research Center, 2421 Suya, Koushi, Kumamoto 861-1192, Japan.
2 National Agriculture and Food Research Organization, Western Region Agricultural Research Center, 6-12-1 Nishifukatsu, Fukuyama, Hiroshima 721-8514, Japan.
3 The Institute of Crop Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8518, Japan.