Volatilization, one of the most important mechanisms of the allelopathic effects of an exotic noxious weed Mikania micrantha, has not been adequately investigated to date. In this study, laboratory bioassays showed that the effects of volatiles from the leaves and flowers of M. micrantha on seed germination and seedling growth were negative for all four tested plants (Lactuca sativa, Chrysanthemum coronarium, Bidens pilosa, Abutilon theophrasti). Moreover, the inhibitory effect of the leaf volatiles was generally greater than that of the flower volatiles. To assess the reason for the above differences and further explore which compounds played the most crucial roles, the volatiles from the two tissues were absorbed by solid phase microextraction (SPME) and identified by gas chromatography and mass spectrometry (GC–MS). Then, 19 and 10 terpenes were determined respectively. α-Terpineol, β-ocimene, β-myrcene, α-pinene and caryophyllene had the maximum differences in content and concentration, which were selected for further bioassays with B. pilosa. The results indicated that morphological indices and SOD activity decreased with increasing concentrations of chemicals, whereas the contents of chlorophyll, soluble protein and MDA represented adverse changes. In addition, significant responses were observed in the treatments with α-terpineol at 1.0 μL·L⁻¹ and lower concentrations, while similar trends were observed in the treatments with β-ocimene, β-myrcene, α-pinene and caryophyllene at 10 μL·L⁻¹ and higher concentrations. It was concluded that terpenoids released through volatilization have an important role in the allelopathic effect of M. micrantha, and the oxygenated monoterpene α-terpineol played a crucial role in these effects.

挥发是外来有毒杂草薇甘菊化感作用的最重要机制之一，迄今为止尚未得到充分研究。在这项研究中，实验室生物测定表明，对于所有四种受试植物（莴苣、菊花、鬼针草、苘麻），金甘菊叶和花的挥发物对种子萌发和幼苗生长的影响均为阴性。而且，叶挥发物的抑制作用一般大于花挥发物。为了评估上述差异的原因并进一步探讨哪些化合物发挥最关键的作用，通过固相微萃取（SPME）吸收两种组织中的挥发物，并通过气相色谱和质谱（GC-MS）进行鉴定。然后分别测定了19和10种萜烯。 α-松油醇、β-罗勒烯、β-月桂烯、α-蒎烯和石竹烯在含量和浓度上差异最大，选取其进行进一步的B. pilosa生物测定。结果表明，随着化学物质浓度的增加，形态指标和SOD活性下降，而叶绿素、可溶性蛋白和MDA含量则出现相反的变化。此外，在1.0 μL·L ^-1及更低浓度的α-萜品醇处理中观察到显着的反应，而在10 μL β-罗勒烯、β-月桂烯、α-蒎烯和石竹烯处理中观察到类似的趋势。 ·L ^-1及更高浓度。得出结论，挥发释放的萜类化合物在微甘草的化感作用中起重要作用，其中含氧单萜α-萜品醇在这些作用中发挥了至关重要的作用。