銀合歡於恆春地區嚴重蔓延，根據林試所恆春研究中心以嘉磷塞注射樹幹方式獲致良好控制效果，本研究進ㄧ步進行嘉磷塞不同濃度處理效果，及嘉磷塞施用後在樹體及土壤之殘毒監測。研究結果顯示不同濃度嘉磷塞處理下，施藥後ㄧ週於注射孔上方約350 cm之銀合歡小葉快速凋萎。整株植株於處理藥劑後其傷害在施藥後1個月最為嚴重，雖然施藥後2個月受害植株開始萌新芽，但新芽多呈褐化畸形。檢測藥劑殘留量顯示藥劑隨時間逐漸消褪，施藥後五個月藥劑殘留量降至施用量的10%，根部則於施藥後三個月偵測出較高殘留量但亦隨時間迅速下降。進ㄧ步以HPLC及放射性同位素分析藥劑流向，研究結果顯示施藥初期藥劑可能於木質部藉擴散方式向周圍轉運，其中大量藥劑累積於兩注射孔中間之韌皮部，並隨時間進行雙向運輸，推測韌皮部為藥劑轉運之主要通道。施藥後45天發現注射孔上方韌皮部有較高之藥劑殘留，於60天後各部位藥劑濃度均隨時間下降，根據放射性同位素活性偵測亦顯示相似變化，然而60天後注射孔上方之放射活性降低而下方放射活性反而增加。探究原因推測由於苗木施藥後於注射孔下方逐漸萌新芽，可能因同化物質source-sink關係改變，使嘉磷塞及其代謝物經由韌皮部重新分配至植體下方，而配合TLC及放射活性分析可以確認此時嘉磷塞除了降解為少部分已知的AMPA、及較多量之sarcosine之外，尚有大量之未知代謝物。Leucaena leucocephala, an exotic species widely spread in Hengchun peninsula, Taiwan, was controlled efficiently by a herbicide of glyphosate . In this study, effects of glyphosate with three different concentrations but an equal amount of dosage were compared, and changes of glyphosate residues in plants and soil environment were also detected. Experimental results showed that rapid wilting of leaflets at height of 350 cm away from glyphosate injection site on basal trunk one week after treatment was found, and serious injury of whole plant occurred within one month. Although newly-formed buds appeared on basal trunk with time, subsequent bud growth was retarded and leaflets were small, chlorotic and deformed. Glyphosate detection showed that residues in plants dissipated rapidly in 3 months, and decreased to 10% 5 months after treatment. Further experiment to study glyphosate translocation in L. leucocephala with HPLC and 14C-glyphosate radioactivity assessment, suggested that most glyphosate residues in xylem likely diffused to surrounding tissues initially, and then temporarily accumulated in phloem located between two injection sites before translocating out subsequently. Therefore, it is implicated that phloem is a primary translocation channel of glyphosate. Glyphosate dissipation analysis revealed that more residues were found in upper phloem 45 days after treatment (DAT) and decreased significantly thereafter. Althrough glyphosate in whole plant including upper, middle and lower parts, was decreased after 45 DAT, radioactivities of 14C-glyphosate and its derivatives in lower phloem accumulated dramatically 90 DAT. The redistribution of 14C-glyphosate and its metabolites to lower phloem of basal trunk is partially resulted from an alteration of source-sink relationship of photosynthate due to the formation of newly-formed leaflets on basal trunk.目次
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中文摘要 ……………………………………………………………i
英文摘要 ……………………………………………………………ii
目次 …………………………………………………………………iii
圖目次 ………………………………………………………………iv
第一章 緒言…………………………………………………………1
第二章 前人研究……………………………………………………4
第三章 材料與方法……………………………………………… 17
第四章 結果與討論…………………………………………………28
ㄧ、嘉磷塞控制銀合歡之效果…………………………… 28
二、嘉磷塞於環境中之消褪……………………………… 35
三、嘉磷塞之轉運研究…………………………………… 52
四、嘉磷塞代謝物變化…………………………………… 60
五、藥劑殘留重新分配之可能原因……………………… 64
六、結論…………………………………………………… 69
參考文獻………………………………………………………… 70
附錄……………………………………………………………… 7
