Evergreen Azalea Cultivars and Breeding Trends in the Taisho Era Inferred by Discovered “Azalea Research Notes” of Kanagawa Agricultural Research Station

Abstract

“Azalea Research Notes 1917 & 1918” of Kanagawa Agricultural research station were discovered at Kanagawa Prefectural Ofuna Botanical Garden in 2006. The notes described not only detailed morphological characters of 338 evergreen azalea cultivars and 7 species, but also their breeding records. From our investigations, 170 of these cultivars are extant, and there is evidence of a breeding trend for greater variation in flower colors and shapes, mainly of Kurume azalea in the Taisho era. These results are valuable because of the sparse information available about morphological features of extinct cultivars and the lack of studies of genetic separation of flower colors and shapes of azalea hybridization in Japan and elsewhere including Europe.