Detection of glyphosate residue in glyphosate-treated Leucaena leucocephala

• Main Authors: Rong-Fang Chen, 陳榮芳
• Other Authors: 王慶裕
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/53486078330055758965

碩士 === 中興大學 === 農藝學系所 === 95 === 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.