| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 105 === The muscadine (Muscadinia rotundifolia) is a dioecious deciduous fruiting vine native to the southeastern U.S. The tropical and subtropical low land may not provide satisfactory chilling hours to most cultivars, thus often leading to uneven budbreak or poor pollination. This thesis investigated the inflorescence initiation and bud responses to chemical forcing in the muscadine to exploit the potential of double cropping system commonly used in grapes. Three-year-old container-grown ‘Carlos’, ‘Jumbo’ and ‘Summit’ vines were used as plant materials. Timing and frequency of inflorescence initiation were observed in 2017. Chemical bud forcing after pruning was performed in the summer of 2016 and in the spring of 2017. Hydrogen cyanamide or hydrogen cyanamide + scarification was applied to examine their efficacy. Bud respiration rates were monitored after bud forcing to evaluate the physiological responses of buds to forcing agents.
In the inflorescence initiation trial, all except for the first bud of ‘Carlos’ on the first to the eighth node of the current shoots developed primordia a month after budbreak. By the end of the second months after budbreak, primordia were visible in all observed buds. However, no further development was observed. Primordia of all the buds did not develop further when examined three months after budbreak.
In the chemical bud forcing trials, 2.5% hydrogen cyanamide or 2.5% hydrogen cyanamide + scarification had little effect on budbreak in ‘Carlos’ and ‘Jumbo’ but had a great effect in ‘Summit’ in the summer trial. In vitro bud respiration increased 1 day after treatment, but declined thereafter. The 2017 spring trial showed that both 5% hydrogen cyanamide and 5% hydrogen cyanamide + scarification advanced budbreak in ‘Jumbo’ and ‘Summit’ as well as increased number of budbreak in ‘Summit’. In vitro bud respiration increased 1 day after forcing and did not decline until a week after forcing. In vivo bud respiration increased 2 days after forcing and did not decrease until two weeks after forcing. Bud respiration dropped to a level similar to the control when approaching budbreak.
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