小蓬草精油化感作用的生物测定

Bioassay of allelopathy of essential oil from Conyza canadensis

采用水蒸气蒸馏法从小蓬草〔Conyza canadensis (L.) Cronq.〕地上部分分离出精油,利用GC-MS技术对该精油的主要化学成分进行了鉴定,结果显示:精油提取率为0.07%;该精油主要含有2,3-二甲基-4(3H)-喹唑啉酮、α-佛手柑油烯、柠檬烯二醇、反式-β-金合欢烯和α-姜黄烯等成分,其中,2,3-二甲基-4(3H)-喹唑啉酮的相对含量最高,达到54.41%。以青菜(Brassica chinensis L.)、白菜〔B. pekinensis (Lour.) Rupr.〕、小麦(Triticum aestivum L.)和高粱〔Sorghum bicolor (L.) Moench〕为供试植物,采用培养皿法对不同质量浓度(0.75、1.5、3.0和6.0 g.L-1)小蓬草精油的化感效应进行了生物测定,结果显示:经不同质量浓度小蓬草精油处理后4种供试植物的种子最终发芽率和发芽指数以及幼苗的根长和株高等4个生物测定指标总体上均低于对照,且随精油质量浓度的提高不断降低,其中,0.75 g.L-1精油处理组的4个生物测定指标均与对照无显著或极显著差异,而6.0 g.L-1精油处理组的4个指标与对照则有显著或极显著的差异。4种供试植物的4个生物测定指标的化感效应敏感指数几乎均为负值,且随精油质量浓度的提高敏感指数的绝对值逐渐增大,说明小蓬草精油对供试植物的化感作用为抑制作用,且抑制作用的强度与精油质量浓度有关。在4种供试植物中,小蓬草精油对青菜种子的最终发芽率的抑制作用最明显,其半抑制浓度(IC50)约为3.0 g.L-1;在4个生物测定指标中,种子最终发芽率以及幼苗根长对小蓬草精油的化感作用较敏感。研究结果表明,小蓬草精油具有一定的化感活性,可将其作为植物源除草剂原料进行开发利用。

Essential oil was obtained from above-ground part of Conyza canadensis（L.） Cronq.by steam distillation method,and main chemical components in the essential oil were identified by GC-MS technology.The result shows that the extraction rate of essential oil from C.canadensis is 0.07%.And main components are 2,3-dimethyl-4（3H）-quinazolinone,α-bergamotene,limonene glycol,（E）-β-farnesene and α-curcumene,in which,the relative content of 2,3-dimethyl-4（3H）-quinazolinone is the highest with a percentage of 54.41%.Taking Brassica chinensis L.,B.pekinensis（Lour.） Rupr.,Triticum aestivum L.and Sorghum bicolor（L.） Moench as tested species,the allelopathic effect of essential oil with different concentrations（0.75,1.5,3.0 and 6.0 g·L-1） was bioassayed by culture dish method.The results show that four bioassay indexes including seed final germination rate,seed germination index,seedling root length and seedling height of four tested species treated by essential oil with different concentrations are generally lower than those of the control and gradually decrease with rising of essential oil concentration.In which,four bioassay indexes in the treatment group with 0.75 g·L-1essential oil have no significant or highly significant differences with those in the control,but in the treatment group with 6.0 g·L-1 essential oil have significant or highly significant differences.The allelopathic effect indexes of four bioassay indexes of four tested species almost are negative values and their absolute values gradually enhance with rising of essential oil concentration,showing that the allelopathic effect of the essential oil is an inhibition role and the inhibition intensity relates to essential oil concentration.Among four tested species,the essential oil has an obvious inhibition effect on seed final germination rate of B.chinensis,and its half-inhibitory concentration（IC50） is about 3.0 g·L-1.In four bioassay indexes,seed final germination rate and seedling root length are more sensitive to the allelopathic effect of the essential oil.It is concluded that essential oil of C.canadensis has a certain allelopathy,and it can be used as botanical herbicide material to exploit and utilize.