1. Field Science Center, College of Agriculture; Ibaraki University; Ami 4668-1 Ami, Inashiki Ibaraki 300-0331 Japan
2. Faculty of Agriculture; Gadjah Mada University; Yogyakarta 55281 Indonesia
3. College of Agriculture; Ibaraki University; 3-21-1 Chuo Ami, Inashiki Ibaraki 300-0393 Japan
4. Graduate School of Environmental Studies; Nagoya University; Chikusa, Nagoya Aichi 464-8601 Japan
5. National Institute of Vegetable and Tea Science, National Agricultural Research Organization (NARO); Kusawa 360 Ano, Tsu Mie 514-2392 Japan