Floral Ontogeny and Sex Determination in Monoecious-type Persimmons

Patterns of floral differentiation were studied in two monoecious-type Japanese persimmon (Diospyros kaki L.) cultivars Hana-gosho and Kakiyama-gaki. In both cultivars, the pistillate and staminate floral primordium started to differentiate in early June, and differentiation progressed until August, when the sepal primordia in pistillate flowers and petal primordia of staminate flowers had become evident. The buds then entered a quiescent, overwintering state. Thus, flower sex of monoecious-type persimmons was determined at a relatively early stage of floral development. Moreover, in both cultivars, sex differentiation was associated with previous history of the current season's shoots. Current season's shoots that bore pistillate flowers differentiated pistillate buds (mixed buds from which pistillate flowers emerge) at significantly higher rates than for shoots that bore staminate flowers. Similarly, shoots that bore staminate flowers produced staminate buds (mixed buds from which staminate flowers emerge) at a higher percentage than shoots that had borne pistillate flowers. With `Hana-gosho', the flower type was also predictable with fair accuracy by bud position on the current season's shoot, i.e., pistillate flowers emerged from distal mixed buds, whereas staminate flowers arose predominantly from basal buds.