本研究係根據丁基拉草(butachlor)對於感性植物生長之抑制反應建立生物檢定方法。於三種供試蔬菜種子發芽試驗中發現白莧對於10.3 mM丁基拉草最為敏感，於處理後第二天即達到100%抑制效果。分析鳳山白菜、青江菜、白莧、油菜心、蘿蔔等5種蔬菜之下胚軸生長對於藥劑之反應，受抑制程度相似，於處理後2-3天內抑制程度達70-80%。此外，五種蔬菜之胚根以鳳山白菜最敏感，於處理後3天抑制達90%。進一步劑量反應分析顯示白莧種子發芽、白莧與鳳山白菜之下胚軸與胚根生長均與丁基拉草濃度對數值呈現線性迴歸關係。另以有機溶劑萃取配合HPLC分析，在濃度範圍0.02至0.10 mM之間可得到積分面積與濃度之間線性關係，且敏感度高出生物檢定10倍。本試驗利用外加定量丁基拉草之土壤為測試樣品，比較生物檢定與儀器分析方法，顯示白莧與鳳山白菜之初期生長反應，尤其是白莧種子發芽後3天之反應可用於預測土壤中丁基拉草濃度。

A biological method, based on butachlor inhibitory effect on plant growth, wasexamined for its application to detect this herbicide. Analysis of seed germinationinhibition showed that, among the 3 vegetables tested, edible amaranth was the mostsensitive to 10.3 mM butachlor within 3 days after treatment (DAT), with 100%inhibition in 2 days. Analysis of hypocotyl growth inhibition showed that 5 vegetables,including Chinese mustard, Ching-Geeng, edible amaranth, field mustard and radish,expressed a similar and constant sensitivity to 10.3 mM butachlor, with 70 to 80%inhibition 2 to 3 DAT. In addition, radicle growth inhibition analysis showed that,among these 5 vegetables, Chinese mustard was the most sensitive to 10.3 mMbutachlor, with 90% inhibition 3 DAT; and field mustard and edible amaranth weremore sensitive to this herbicide than the remaining 2 vegetables. Further dose-responseanalysis indicated that linear regressions existed between seed germination of edibleamaranth or hypocotyl and radical growth of edible amaranth and Chinese mustard inone to three days and the log-transformed concentrations of butachlor. For theinstrumental detection of butachlor, which organic solvent extraction and HPLCanalysis, a linear regression between integrated peak area of HPLC system andbutachlor concentration in extraction solution was observed ranged from 0.02 to 0.10mM, with a ten-fold higher detection sensitivity than bioassay system. A comparison ofbiological with instrumental methods using a soil spiked with a given concentration ofbutachlor as the test sample showed that bioassay system consisting of early growthresponses of both edible amaranth and Chinese mustard, especially the seed germinationresponse of edible amaranth within 2 to 3 DAT, could be recommended to predictbutachlor concentration, to replace the expensive HPLC system. The latter is harmful toenvironment due to the toxic organic solvents used for instrumental analysis.Nomenclature: Biological marker; butachlor; Chinese mustard, Brassica rapa L.; fieldmustard, Brassica campestris L.; cabbage, Brassica oleracea L. var. Capitata;Ching-Geeng, Brassica chinensis L., ‘Ching-Geeng’; edible amaranth, Amaranthustricolor L.; water convolvulus, Ipomoea aquatica Forsk; radish, Rapanus sativus L..