Title: The Extent of Intersubgeneric Cross Compatibility between Japanese Plum (Prunus salicina Lindl.) and Peach (P. percica Batsch.)
Abstract: Intersubgeneric crosses between seven peach cultivars and 22 Japanese plum cultivars were carried out to produce intersubgeneric hybrid plants that were expected to have potential for new fruit cultivars and rootstocks for peach.No hybrid plants were derived from peach X plum crosses, whereas many hybrid plants were derived from the reciprocal intersubgeneric crosses.Among the plum cultivars pollinated with peach cultivars, 'Jinsanto', 'Formosa', 'Kasaharahatankyo', 'Oishiwase' and 'Manzaemon' showed high fruit set rates of more than 300/0.The rates of harvested fruits in the nine crosscs ranged from 5.40/0 to 25.40/0.The rates of perfect seeds ranged from about 700/0 to 900/0 as observed in open-pollinated plum cultivars.In comparison between open pollination and pollination with 'Hakuho' pollen, the size of embryos was almost same in 'Yuko' and 'Oishiwase' and slightly small in 'Sordum' pollinated with 'Hakuho'.All of the perfectly developed embryos and some of the imperfectly developed embryos germinated and grew up to seedlings.The leaves of seedlings showed intermediate shapes between their parental peach and plum cultivars.Flower bud formation occurred in the intersubgeneric hybrid plants.However, most of the hybrid plants did not flower because of underdevelopment of the flower buds.All flowers developing in a few hybrids showed very abnormal morphology and dropped immediately after the anthesis.The meiotic products in the anthers were irregular and showed high sterility.