Abstract
Rhododendron reticulatum is commonly used in landscaping because of its beautiful flowers, and it is also commonly found in abandoned secondary forests in western Japan. In this study, we investigated flowering in the crown and shoot levels of R. reticulatum and assessed the dynamics involved in flowering. We found that flowering rate increased with an increase in the basal diameter of stem. With regard to floral bud formation on the shoot, foliate buds formed on shoots with a large diameter, and floral buds formed on shoots with a small diameter. Floral shoots formed in the previous year did not allow floral bud formation in current year. Dry mass of floral shoots was similar to that of foliate shoots, but the morphological characteristics of lateral shoots, such as length, branching ratio, and cross-sectional growth, were different between floral shoots and foliate shoots. Thus, flowering in the crown is regulated by the basal diameter of the stem, whereas floral bud formation is regulated by the production of floral shoots in the previous year. We found that crowns that grow to a particular size develop flowers and extensive flowering in the crown occurs when all shoots show extensive formation of floral buds.
