|Budget Amount *help
¥6,500,000 (Direct Cost : ¥6,500,000)
Fiscal Year 1991 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1990 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1989 : ¥5,000,000 (Direct Cost : ¥5,000,000)
We tried to clarify the patterns of sex expression and their regulation in monoecious-type persimmons, and the following results were obtained.
1. The pistillate and staminate floral primordium differentiated in early June and progressed until August when the sepal primordial in pistillate flowers and petal primordial of staminate flowers had become evident. The buds then entered the quiescent, overwintering state. Thus, flower sex of monoecious-type persimmons is determined at a relatively early stage of floral development.
2. The flower type on the current shoots is somehow strongly related to the determination of the flower type, being initiated within the buds on the same shoot. That is, shoots that bore pistillate flowers were differentiating pistillate buds at significantly high rates, while shoots that bore staminate flowers were producing more staminate buds. The bud position on the shoot also corresponded with sex expression, i. e. pistillate flowers emerge from distal mixed bud
s, whereas staminate flowers arise predominantly from basal nodes.
3. Cytokinin spray to flower buds immediately after budbreak was successful in converting male flowers, into hermaphroditic ones. Moreover, cytokinin was also effective at flower differentiating stages to convert sex expression. In this chse, shoots of 'Taiwan- syoshi' were sprayed with BA at 1000 ppm in June, and they produced shoots bearing hermaphroditic flowers when they had second sprouts in the same year, being compared that control 1-year shoots produced only male-bearing shoots in second sprouts.
4. Endogenous cytokinin and inhibitor activity of male- and female-bearing shoots was examined at flower differentiation time. Methanolic extracts were purified with partitions to organic solvents, and injected into HPLC. The fractions from HPLC were bioassayed with Amaranthus test for cytokinins and rice seedling test for inhibitors, respectively. Several active fractions were obtained for both cytokinins and inhibitors, but they had no differences between male- or female-bearing shoots. Less