Effects of Inflorescence Thinning and Types of Reproductive Shoots on Flower Sex Ratio,FruitSetand Fruit Quality of ‘No Mai Taz’ (73-S-20)Litchi(Litchi chinensis Sonn.)

Abstract

Poor yield and unstable of flowering have been reported as the major production problems of‘No Mai Tsz’(73-S-20)litchi in Taiwan. The objective of this study was to document the effect of inflorescences thinning and types of reproductive shoots on the flower sex ratio, fruiting and fruit quality. 1/2 to 2/3 flowers per inflorescences were removed by hand right before 1 and 3 weeks of anthesis (female flower is full blooming). That inflorescence thinning before 3 weeks of full anthesis could affect flower sex ratio, but could not promote fruit set and fruit quality in ‘No Mai Tsz’ (73-S-20) lithci. We investigate the axis length of inflorescences, leaf length, chlorophyll readings and gas exchange rate at 1 week after leaflet unfolding of mixed shoot. In second experiment we investigate the generative shoots, mixed shoots and transition shoots on field growth tree. The gas exchange rate were determined at over fruit growing period. That concluded that photosynthetic capacity comapred within leaflet of leafy inflorescences and generative shoot are no difference, but leaflet of mixed has a samller size than leaflet of generative shoot. Generative shoots had highest flower numbers (588), while mixed shoots (459) and transition shoots (221) followed respectively, suggesting that it had a gradual reduction of flower numbers associated with the attribute of leafy reproductive shoots. No difference was recorded in sex ratio of M1, F and M2 flowers among all types of shoots. The major wave of fruit drop, more than 80%, occurred within 5 weeks after full bloom, regardless of the types of shoots. The number and proportion of fruit retained at harvest in generative, mixed and transition shoots were 1.4、0.7%, 2.3、1.5% and 2.1、2.4%, respectively. There was no difference in fruiting and yield performance among all types of shoots. Most characteristics of matured fruit, including weight of fruit, aril and seed as well as aril sweetness, did not vary with types of shoots, besides the pericarp weight of transition shoots was inferior to that of other two types of shoots. defoliate of mixed shoot on difference inflorescences growth stage, undefoliate on mixed shoot and generative shoot are control. Our results indicated that inflorescences leaf of mixed shoot inhibit inflorescences development, resulting in Total flower number of mixed shoot were much less than that of generative shoot. Whihe inflorescences leaf of mixed shoot have potential of stabilizing fruit set and does not affect fruit quality.結實不良與開花不穩為‘糯米糍’(73-S-20)荔枝生產之重要問題，為瞭解疏花序、花序型態及混合花序除葉是否影響花性、著果及果實品質。分別於盛花前1週及三週進行疏花序，結果顯示盛花前3週疏花序可能改變荔枝花性，但不論盛花前1週或3週疏花序著果數為1.7顆，著果率2.4-2.9%及果實品質均與對照組無差異。於混合型花序(mixed shoot)小葉展開後一週進行花序主軸長度、小葉長、葉綠素讀值及光合作用氣體交換速率之調查，另調查三種花序型態小葉及結果枝葉片之光合作用能力，結果顯示三種花序型態小葉與結果枝葉片能力無異，混合花序小葉於盛花時自身呼吸損耗與碳同化能力達到平衡，雖然光合作用能力與營養梢葉片無異，但其葉片大小僅有營養梢葉片之50%。比較純花序(generative shoots)、混合型花序(mixed shoots)及過渡型花序(transition shoots)等三者單一花軸(panicle)之花性、著果數、著果率及果實品質。結果顯示，總花數以純花序之588最多，混合型花序459次之，過渡型花序221最少，但各型態花序之花性比例並無差異。不論何種花序型態均於盛花後五週內有一明顯之落果高峰(80%以上小花掉落)，純花序最終著果數為1.4，著果率為0.7%，混合花序為 2.3、1.5%，過渡型花序為2.1、2.4%，但三者並無顯著差異，果實性狀除過渡型花序之果皮重低於其它兩者，單果重、果肉重、種子重及糖度亦均無差異，試驗結果顯示，花序型態影響‘糯米糍’(73-S-20)荔枝總花數但不影響花性比例、最終著果數與果實性狀。於混合花序不同生長階段進行除葉，並以未除葉之混合花序及純花序為對照，結果顯示混合花序較早除葉具有較多的小花數，至盛花時方除葉則已無法改變，而不管除葉時期早晚均不影響花性比例。與混合花序相較，純花序具有較高之著果數及著果率，但保留混合花序葉片具有穩定著果之潛力，但仍需進一步確認。而通霄試區因盛花期適逢梅雨，因此處理效益並不顯著，而混合花序葉片並未影響73-S-20之果實品質。中文摘要 i Abstract ii 目次 iv 表目次 vii 圖目次 viii 第一章、緒言 1 第二章、前人研究 3 2.1. 荔枝枝梢生長特性 3 2.2.影響荔枝花芽分化之因子 3 2.2. 花序型態 4 2.3. 花性比例 5 2.4. 花器構造 6 2.5. 胚囊及胚胎發育 6 2.6. 著果及果實發育模式 7 2.7. 碳水化合物供需 8 2.8. 葉片光合作用速率 8 2.9. 疏花序 9 2.10. 研究策略與目的 10 2.11參考文獻 11 第三章、疏花序對‘糯米糍’ (73-S-20)荔枝花性、著果與果實品質之影響 19 3.1. 前言 20 3.2. 材料與方法 22 3.4. 結果 23 3.5. 討論 25 3.6. 結論 28 3.7. 參考文獻 29 Abrstract 32 第四章、‘糯米糍’ (73-S-20)荔枝帶葉花序之生育及光合作用特性之研究 49 4.1. 前言 50 4.2. 材料與方法 51 4.3. 結果 52 4.4. 討論 52 4.5. 結論 53 4.6. 參考文獻 55 Abstract 57 第五章、花序型態對‘糯米糍’ (73-S-20)荔枝花性、著果與果實品質之影響 68 5.1. 前言 69 5.2. 材料與方法 70 5.3. 結果 71 5.4. 討論 71 5.5. 結論 73 5.6. 參考文獻 74 Abstract 76 第六章、混合花序除葉對‘糯米糍’ (73-S-20)荔枝花性、著果與果實品質之影響 83 6.1. 前言 84 6.2. 材料與方法 85 6.3. 結果 86 6.4. 討論 88 6.5. 結論 90 6.6. 參考文獻 91 Abstract 93 第七章、總結 102 附錄 104 石蠟切片製作與染色 104 Studies on Growth of Development and Photosyntheic Characteristics of Leafy Reprodctive Shoots in‘No Mai Tsz’(73-S-20)litchi. 11