三种菊科入侵植物的生长与化学防御的关系研究

“生活史理论”认为，植物可利用的资源总量是有限的，在植物的不同功能之间存在着此消彼长的权衡关系。入侵植物的生长和化学防御一般优于本地植物，那么其生长与化学防御之间是否存在权衡及其权衡关系怎样，目前尚不清楚。以广东省3种菊科入侵植物三裂叶蟛蜞菊（Wedelia trilobata （L.） Hitchc.）、飞机草（Eupatorium odoratum）和薇甘菊（Mikania micrantha）]为研究对象，并分别以近缘或伴生的本地植物蟛蜞菊（Wedelia chinenses）、华泽兰（Eupatorium chinense）和鸡矢藤（Paederia scandens）]为对照，研究入侵植物的生长特性（相对生长率和比叶面积）与化学防御物质（缩合单宁和总酚）含量，并基于这2种光合碳分配的主要形式，探讨入侵植物生长与化学防御之间的权衡关系。结果表明：3种入侵植物的相对生长率均高于本地对照种；薇甘菊的比叶面积大于对照种，而其他2种无明显优势。薇甘菊和三裂叶蟛蜞菊的缩合单宁显著高于对照种，飞机草的总酚含量高于对照种。我们的结果显示，入侵植物的生长和化学防御均优于本地植物，但它们的碳同化能力相近；因此，入侵植物特殊的内在资源分配与利用机制可能是其成功入侵的关键。

Growth and chemical defense in three Asteraceae invasive weeds in lower subtropical China

A universal theory in ecology is that the allocations of limited resources to growth and defense are trade-off, while this theory appeared not to hold for invasive plants according to the previous studies. In this study, three invasive Asteraceae plant species in the Guangdong province i.e., Eupatorium odoratum, Mikania micrantha, Wedelia trilobata, and their congeneric or co-occurring native plant species i.e., Eupatorium chinensis, Paederia scandens, Wedelia chinensis were used to detect if there is a trade-off between growth and chemical defenses on the basis of carbon allocation, and investigate the trade-off relations between them. All the three invasive Asteraceae had higher relative growth rate （RGR） as compared to their related native counterparts, and M. micrantha had higher specific leaf area （SLA） as well. Two invasive Asteraceae （i.e., M. micrantha and W. trilobata） had higher condensed tannin content, while the other invasive species E. odoratum had higher total phenolics content, as compared to their native species. Our results indicate that the invasive plants have similar carbon assimilation but different carbon allocations between the growth and chemical defense, thus implying that the special underlying carbon utilization mechanism may be a key for their successful invasions.