Search

The trait of long-lasting flower corolla with temporal change of colour exists in Japanese evergreen azalea. This trait called "misome-sho" has been found in several species and cultivar groups from Edo era. For the purpose of application of this trait for breeding, we investigated several characteristics of these cultivars. Wild species of Rhododendron kaempferi, R. indicum and R. macrosepalum and long-lasting flower cultivars were used in this study. All long-lasting flower cultivars have smaller corolla compared to wild types and have stomata in the corolla surface, while wild types do not have stomata in their surface. Pot planted long-lasting flower cultivars kept their corolla more than 100 days and corolla colour was changed from red or purple-red in anthesis to green later. In contrast, wild type plants in pot finished flowering in about 20 days. Microscopic observation of the longitudinal section of flowers revealed that the abscission layer in the basal portion from wild type corollas is not observed in long-lasting flower cultivars. These cultivars have high pollen fertility and stabilized seed set ability. Inheritance of this trait is investigated using cross progenies. The long-lasting trait of corolla would be derived from the sepaloid nature of petals caused by homeotic gene mutation.