不同光照和水分条件下鬼针草属入侵种与本地种生长、光合特征及表型可塑性的比较

Comparison of growth, photosynthesis and phenotypic plasticity between invasive and native Bidens species under different light and water conditions

为探讨鬼针草属(Bidens)入侵种的入侵性,利用同质园种植实验比较了该属入侵种三叶鬼针草(Bidens pilosa)和大狼耙草(B.frondosa)与本地种金盏银盘(B.biternata)和狼耙草(B.tripartita)在光照与水分交互作用下的形态、生长、生物量分配、光合特征及其表型可塑性的差异。结果表明:入侵种的株高和生物量在低光低水条件下与本地种相似,在有利的光照和水分条件(高光高水)下显著高于本地种,相对生长速率在高光条件下均高于本地种。入侵种在高光处理下增加了对地下部分的资源投入,在低光处理下增加了对叶的投入,且低光低水条件下比叶面积显著高于本地种。这些特性可能提高了入侵种对资源的捕获和利用能力,使其既能耐受不利的环境,又能在有利的条件下表现最大化。入侵种和本地种的形态、生长和光合生理等参数对水分变化的可塑性指数均较小,对光照变化的可塑性指数均较大。入侵种的多数变量对光照响应的可塑性指数大于本地种,较大的表型可塑性可能促进其成功入侵。另外,入侵种和本地种的光合生理参数无显著差异。相对于光合特征,形态、生长、生物量分配和表型可塑性等可能对鬼针草属入侵种的入侵性更为重要。

To explore the traits related to the invasiveness of exotic Bidens species in China, we compared the morphology, growth, biomass allocation, photosynthesis, and phenotypic plasticity of two invasive Bidens species （B. pilosa and B. frondosa） with two native congeners （B. biternata and B. tripartita） under different light and water conditions in a common garden. The results showed that the invasive and native species displayed similar plant heights and total biomass under unfavorable conditions （i.e. low light and low water treatment）. However, under favorable light and water conditions （i.e. high light and high water treatment）, the invasive species showed significantly greater plant height and total biomass than the native congeners. Furthermore, in high light treatments, the relative growth rate of the invasive species was higher than that of the native species. The invasive species allocated more resources to root biomass at high light levels compared to low light levels, while they allocated more resources to leaf biomass at low light levels compared to high light levels. Specific leaf area of the invasive species was greater than that of the native congeners under low light conditions. These traits may enhance the abilities of invasive species to capture and utilize resources, enabling them to withstand adverse environmental conditions or to respond more positively to favorable conditions. The phenotypic plasticity indices of invasive and native species for morphology, growth, and photosynthetic parameters were low for water availability and high for light intensity. However, for most variables, invasive species showed a higher phenotypic plasticity index than native congeners, and this may contribute to their invasion success. In addition, there were no significant differences for photosynthetic parameters between invasive and native Bidens species under any treatment. In conclusion, this study shows that morphology, growth, biomass allocation, and phenotypic plasticity may play more important roles than photosynthetic parameters in the success of invasive Bidens species.