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Detection technique of glufosinate and its dissipation in soil
|摘要:||有關固殺草除草劑之檢測技術，本研究利用生物檢定法，分別以六種蔬菜種子之胚根生長為指標，發現白莧(edible amaranth)及鳳山白菜(Chinese mustard)之胚根生長較其他蔬菜敏感，處理後3天之ED50約0.2-0.4 mM。進一步以白莧為材料進行分析，發現在0.015-15.08 mM 固殺草範圍內，胚根生長與濃度對數值呈線性負相關。若以六種蔬菜之三葉期幼苗為材料，可發現青江白菜(Ching-Geeng)及油菜心(field mustard)對於固殺草較其他四種蔬菜敏感，根據劑量反應分析可知，處理後三天青江白菜之ED50為 95.3 nM，且在 75-750 nM範圍內，幼苗傷害指數與濃度對數值呈線性關。本研究亦利用銨與glyoxylate作為化學標誌，發現青江白菜、油菜心與水稻三葉期幼苗於0.26 mM 固殺草處理後24小時內，以感性青江白菜之銨累積量達最高，其次為油菜心，而耐性水稻則於12小時後即不再增加。隨著固殺草施用濃度增加，青江白菜銨累積量亦快速增加，在0.0075-1.5 mM範圍內，累積量與施用濃度之對數值呈線性關係。至於glyoxylate之累積量則在0.0075-0.15 mM 固殺草範圍內，累積量與濃度對數值呈線性關係，顯然生物檢定以青江白菜三葉期幼苗之銨累積變化對於固殺草有較大偵測範圍。
本研究分別利用UV及螢光偵測技術配合SAX column建立固殺草之分析方法。以UV偵測標準品固殺草時發現195 nm較210 nm可得到較佳之偵測極限，4.6 vs. 18.85 nmole，其分別在4.6~148及18.85-150.8 nmole固殺草範圍內呈線性關係。若先以FMOC衍生固殺草配合螢光偵測時，可獲極佳之分析效果。偵測極限高至2.3 pmole，且於2.3~18.5 pmole範圍內呈線性關係。利用本分析法證實，土壤中之固殺草在微生物分解下，於三個月內由400 ppb降至0.29 ppb以下，而無微生物活動下，延至7個月後始下降至0.29 ppb以下，此現象不受通氣與否影響。
此外，玉米田間及溫室依推薦用量(每公頃5 L稀釋至600 L)施用下，噴施藥劑一週後發現，玉米田間土壤之固殺草含量於施藥後一週，改由原先98 ppb降至0.29 ppb以下。而溫室盆栽土壤之固殺草則於四週內由43 ppb降至0.29 ppb以下，推測田間可能具有較複雜的微生物相，及開放空間下隨灌溉流失而加速固殺草之消退。|
In order to establish the glufosinate detection system, both direct and indirect techniques were conducted. Bioassay, an indirect technique, based on either the radicle growth inhibition or the injury index of seedlings of 6 vegetables was tested. Dose- response analysis on the basis of the former trait showed that both Chinese mustard and edible amaranth were more sensitive to glufosinate than other 4 plant species. Another bioassay using 3-leaf seedlings as material showed that both Ching-Geeng and field mustard were more sensitive to glufosinate than other 4 tested plants. A linear regression between injury index of Ching-Geeng and the log-transformed concentration of glufosinate ranged from 75 to 750 nM could be obtained 1d after treatment. In this experiment, chemical marker technique based on the accumulations of ammonium and glyoxylate showed that Ching-Geeng accumulated more ammonium than field mustard 24 h after application of 0.26 mM glufosinate, whereas the tolerant rice no more increased from 12 HAT. In addition, ammonium accumulation in Ching-Geeng had a linear regression to the log-transformed concentrations of glufosinate ranging from 0.0075 to 1.5 mM glufosinate. However, although similar relationship between glyoxylate and glufosinate ranged from 0.0075 to 0.15 mM was also obtained, applied concentration of glufosinate more than 0.15 mM resulted in the unexpected decline of glyoxylate. Therefore, the ammonium accumulation in 3-leaf Ching-Geeng is highly recommended as a sensitive chemical marker to detect glufosinate indirectly. Regarding the direct detection of glufosinate, HPLC analysis based on either UV or fluorescence spectrophtometry, coupled with or without FMOC derivatization, was tested. Obviously, UV detection at 195 nm had a higher sensitivity than at 210 nm; and after FMOC derivatization, glufosinate could be detected more efficient by fluorescence detection than by UV detection, the former had a better detection limit at 25 pmol. In this study, we found that the glufosinate in soil degraded from 400 ppb to less than 0.29 ppb within 3 months under the microbial activity, but this dissipation without biodegradation was lasted over 7 months. In field experiment, glufosinate in corn field applied with a recommended dose dissipated from 98 ppb to less than 0.29 ppb one week after treatment, and that in pot soil in greenhouse reduced from 43 to less than 0.29 ppb within 4 weeks, the complicated edaphic microbial activity and climate in field might promote glufosinate dissipation.
|Appears in Collections:||農藝學系|
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