Production of high-quality cut flowers of Oriental hybrid lilies during winter in warmer regions of Japan

Production of cut flowers of Oriental hybrid lilies in Japan has expanded markedly since 1990, because the importation of bulbs from Holland has increased rapidly following reduction in the quarantine regulations between the two countries. Oriental hybrid lilies can be marketed year-round through long-term storage of bulbs at temperatures below freezing point of pure water (usually -1.5 to -2.0degC). Bulbs harvested in Holland in November are shipped to Japan under precooled conditions at 1-2degC and arrive in mid-January. When planted after arrival and forced in plastic houses maintained at a minimum temperature of 15degC, the bulbs flower in mid-April to June depending on planting time. On the other hand, bulbs are also transferred and stored at -1.5 to -2.0degC for retarding culture in Holland and Japan. For these bulbs, flowers are harvested 2-3 months after planting, depending on the cultivar and growing season. In warmer regions of Japan, as in Kochi Prefecture, with longer sunshine hours in winter, continuous cut flower production of Oriental hybrid lilies is desired during the period from November to May, especially from February to early April. In order to harvest good-quality cut flowers from February to early April, bulbs ready for planting in November to January are required, but imported bulbs from Holland cannot be used due to the limited storage period at -1.5 to -2.0degC of 6-9 months. This study was carried out to establish a procedure to achieve winter production of high-quality cut flowers.