外来植物黄顶菊根、茎、叶的化感作用初探

对黄顶菊［Flaveria bidentis (L.) Kuntze］营养器官进行了解剖学观察，发现其根、茎、叶均存在分泌结构或分泌物。以白菜（Brassica pekinensis Rupr.）作为受试植物，从白菜种子发芽率、幼苗的简化活力指数、幼苗下胚轴及胚根伸长、幼苗中叶绿素、丙二醛（MDA）及可溶性糖（WSS）含量等指标对黄顶菊根、茎和叶水浸提液的化感作用进行了探讨。研究发现，根、茎、叶的浸提液降低了白菜种子发芽率和幼苗胚根长度；幼苗中叶绿素a及总叶绿素随浸提液浓度的升高最终呈下降趋势；MDA和WSS含量随叶片和茎的浸提液浓度升高相应增加。白菜种子萌发及幼苗生长对黄顶菊不同器官浸提液反应有差异，其对叶片浸提液的浓度响应最明显。

Preliminary studies on allelopathy of the aqueous extracts of an alien plant, Flaveria bidentis

The possible allelopathic effects of the aqueous extracts of Flaveria bidentis (L.) Kuntze on seed germination, seedling growth, chlorophyll and total chlorophyll, melondialdehyde (MDA) and water soluble sugar (WSS) content of Brassica pekinensis Rupr. Jinqing 60 were investigated. The results showed that the germination percentage and root length were significantly reduced when applied with the aqueous extracts of different organs of F. bidentis. The contents of chlorophyll and total chlorophyll in B. pekinensis seedlings were gradually decreased as the concentration of the extracts became higher; the content of MDA and WSS in the seedlings were more sensitive to the extract concentrations of leaves and stems. Our findings were also supported by the secretory structures or secretions in the roots, stems and leaves of F. bidentis under light microscope. The results suggested that the allelopathy of F. bidentis might be the causative factor responsible for the observed reduction in seedling growth of B. pekinensis. Moreover, more allelochemicals existed in the leaves than in other organs of F. bidentis.