| Summary: | 碩士 === 國立中興大學 === 園藝學系 === 91 === Effects of panicle pruning and plant growth regulation treatments on floral sex expression and fruiting of `Yu Her Pau´ litchi were studied. The results showed that the peak blooming period of female and male flower occurred about 12~20 days and 20~32 days after the first flower opened, respectively. The whole blooming period could last for 36~44 days. The flower number in strong or normal vigorous shoots were higher than that in weak vigorous shoots. Strong vigorous shoot had 12.1% female flowers, while normal and weak vigorous shoot only had 9.5% and 9.2%, respectively. The number of flower at the basal was higher than those at the middle and the distal portions of panicle. The basal portion of panicle had 14.3% female flowers, whereas the middle and distal portions only had 12.3% and 10.2%, respectively. The percentage of female flower was increased and blooming period was prolonged 12~16 days by panicle pruning.
Poor yields often occurred because of poor fruit set in `Yu Her Pau´ litchi. Sixty percent of young fruit abscised in the frist week after fruit set and the total percentage of fruit abscission was over 80% at harvest. The number of fruit set and final harvested fruit were higher in strong vigorous shoots than in normal and weak vigorous shoots. The numbers of fruit set and harvest fruit were increased by the treatment of leaving only 4 paracladiums on an panicle. Retained paracladium at the base of panicle had better fruit set than retained paracladium at the middle and distal portions. The number of harvested fruit increased by twofold when treated with 40 ppm NAA at the time of two weeks after full female bloom. Fresh weight, sizes of fruit and seed, dry weight and total soluble sugar of seed in abscised fruit were lower than those in normal fruit.
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