Use of the staminate flowers of ‘Saijo’ persimmon

‘Saijo’ persimmon (Diospyros kaki Thunb.) is a local cultivar in western Japan. Its origin is said to be in Hiroshima during the period of Heian and Kamakura eras (794~1333) in Japan. ‘Saijo’ fruit has excellent eating quality with rich sugars and smooth/melting flesh texture, which is highly appreciated by the market and consumers. It is generally known that ‘Saijo’ normally has only female flowers which are pistillate flowers without stamens. Hence, the breeding program to create succession cultivars using ‘Saijo’ as a pollen parent is impossible. Thanks to the careful observations by the orchard managers, the spontaneous bud sports of ‘Saijo’ forming male flowers (androgenic mutation branches) have been found in several commercial orchards in the Izumo area of Shimane Prefecture which lies to the north of Hiroshima. That male flower with functional stamens was able to develop normal pollen. However, the viability of the pollen of ‘Saijo’ was low. The pollen lost its germination capacity even though after temporal storage for a few days. Fortunately, the artificial pollination for the crossbreeding using the ‘Saijo’ pollen had just enough success by using the fresh ones soon after the dehiscence. Seeds derived from self- or pseudo-self-cross of ‘Saijo’ strains were obtained. Most of them were germinated in vitro to grow the progeny plants securely. When the seeds were germinated in the soil, it was difficult to establish the seedling because of the abortion of the hypocotyl tip. In a couple of established seedlings, the symptoms of inbreeding depression, such as less growth vigor and aberrant leaf development, were observed. We provide a record of discoveries of male flowers in ‘Saijo’, and a progress report about the self-cross breeding of ‘Saijo’ × ‘Saijo’.