圓葉葡萄的花序創始與催芽試驗

Abstract

圓葉葡萄 (Muscadinia rotundifolia) 為雌雄異株的溫帶落葉果樹，原生於美國東南方。熱帶與亞熱帶低海拔地區之冬季低溫常無法滿足多數品種之低溫需求導致春季萌芽不整齊或授粉不良等問題。本論文探討圓葉葡萄之花序創始及其對化學催芽之反應，以了解適用於葡萄的一年二收栽培方式是否也適用於圓葉葡萄。所使用之植物材料為盆栽3年生之‘Carlos’、‘Jumbo’和‘Summit’三品種。花序創始試驗於2017年春季，透過芽體解剖的方式，觀察並記錄芽體內部的花序創始過程及時間。催芽試驗於2016年夏季以及2017年春季進行修剪後，施用氰胺或氰胺+刻傷處理，紀錄萌芽期及萌芽數。同時測量催芽後的芽體呼吸率變化，探討化學藥劑催芽後芽體呼吸率變化與萌芽時間的相關性。 花序創始試驗結果顯示，萌芽一個月後之新生枝條，第一至第八節位的芽體，於萌發一個月後僅‘Carlos’第一節位未形成原基(primordia)，其餘節位均已形成，而‘Jumbo’和‘Summit’則均形成；萌發兩個月後則三個品種的所有節位之芽體皆可見原基，但是並未發展成花穗原體；萌芽三個月後三個品種維持與萌芽兩個月後相似的階段。 催芽試驗顯示，於夏季施用2.5%氰胺或2.5%氰胺＋刻傷對‘Carlos’和‘Jumbo’的催芽效果有限，但對‘Summit’具有良好的催芽效果。而在離體試驗中發現，催芽處理後一天，芽體呼吸率上升，但在第二天便開始下降。於春季施用5%氰胺或5%氰胺＋刻傷對‘Jumbo’和‘Summit’有提早一週萌芽的效果，但僅對‘Summit’有提高總萌芽率的效果。在離體試驗中發現，催芽後一天的芽體呼吸率會上升並持續至一週後才開始下降。而在田間試驗中發現，催芽後第二天的芽體呼吸率上升，持續兩週始開始下降，並於植株萌芽前下降至與對照組相近的數值。

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.