克隆整合对入侵杂草空心莲子草和本土莲子草生长及光合性能的影响

目的 在我国，外来入侵植物空心莲子草Alternanthera philoxeroides常与本地莲子草 A. sessilis同域分布且占据生态优势。本文探讨克隆整合与空心莲子草强竞争力间的关系。方法 通过同质园试验，对空心莲子草和莲子草先端与基端匍匐茎的连接处进行保持连接(克隆整合)与剪断处理(无克隆整合)，分别测量不同克隆整合处理下2种植物先端分株、基端分株及整个克隆片段地上部分及根系的生长、光合性能及生物量分配情况，比较2种植物克隆整合能力的大小。结果 克隆整合处理下，空心莲子草先端分株的茎长、基端分株的叶片数及整个克隆片段的叶片数及茎长显著增加，细根数、总根数及一些光合指标(如光补偿点、气孔导度等)也显著提高；莲子草先端分株、基端分株及整个克隆片段的地上(下)生物量、总生物量、粗(细)根数及总根数也显著增加。克隆整合处理下空心莲子草先端分株、基端分株或整个克隆片段的地上(下)生物量、总生物量及一些光合指标(如净光合速率、蒸腾速率、气孔导度)显著高于莲子草。结论 空心莲子草和莲子草均能在一定程度上从克隆整合中受益，但空心莲子草的克隆整合能力要显著强于本地莲子草，能通过克隆整合作用挤占莲子草的空间生态位，从而形成自然生境中的竞争优势。

Effects of clonal integration on growth and photosynthesis of invasive weed Alternanthera philoxeroides and native A. sessilis

Objective The alien invasive plant Alternanthera philoxeroides is often sympatric with native congener A. sessilis, but occupies an ecological advantage over A. sessilis in China. This study aimed to explore the relationship between clonal integration and the strong competitiveness of A. philoxeroides.Method In a common garden experiment, the stolon connection between the apical and the basal ramets of A. philoxeroides and A. sessilis were left intact (clonal integration) or disconnected (without clonal integration), and the growth, photosynthesis, and biomass distribution of the apical ramets, the basal ramets, and the whole fragments of the two plants under different clonal integration treatments were examined to compare the clonal integration abilities of the two plants.Result The stem length of the apical ramets, the number of leaves of the basal ramets as well as the leaf number and the stem length of the whole fragment of A. philoxeroides all significantly increased under clonal integration treatment. Moreover, the number of fine roots, total roots, and some photosynthetic indicators (such as light compensation point, stomatal conductivity, etc.) of A. philoxeroides all significantly increased under clonal integration treatment. Similarly, the aboveground/belowground biomass, the total biomass, the number of coarse/fine roots, and total number of roots of the apical ramets, the basal ramets, and the whole fragment of A. sessilis also significantly increased under clonal integration treatment. However, the aboveground/belowground biomass, the total biomass, and some photosynthetic indicators (such as net photosynthetic rate, transpiration rate, and stomatal conductance) of the apical ramets, the basal ramets, and the whole fragment of A. philoxeroides were significantly higher than those of A. sessilis under clonal integration treatment.Conclusion Both A. philoxeroides and A. sessilis can partly benefit from clonal integration, and A. philoxeroides has a stronger clonal integration ability than A. sessilis. A. philoxeroides might occupy the spatial niche through clonal integration, thus forming competitive advantage in natural habitats.