不同土壤养分水平下2种外来鬼针草和近缘本地种的比较研究

【背景】鬼针草属白花鬼针草和三叶鬼针草原产于热带美洲,入侵我国后给生态环境、农业经济等造成严重的危害和影响。目前,关于它们的研究主要针对单个物种。为了更好地理解这2种外来鬼针草的入侵能力和入侵机制,本文开展了这2种入侵种与近缘本地种之间的比较研究。【方法】通过盆栽试验,设置低肥和高肥2个养分水平,测量和计算2种外来鬼针草与近缘本地种金盏银盘在不同土壤养分水平下的形态和生长参数、生物量及其分配、繁殖持续期、单株种子产量以及表型可塑性指数等。【结果】在低肥条件下,除了繁殖持续期和种子产量外,2种外来种和本地种的大多数参数均无显著差异。但在高肥条件下,外来种白花鬼针草的总叶面积、比叶面积、叶面积比、繁殖持续期和种子产量明显高于本地种,而三叶鬼针草总叶面积、比叶面积、总生物量、相对生长速率却显著低于本地种。在对土壤养分的可塑性方面,白花鬼针草在株高、总叶面积、比叶面积、总生物量、叶面积比、相对生长速率、平均叶面积比和种子产量方面的可塑性均高于其他2种植物;三叶鬼针草与金盏银盘相比,大多数参数的可塑性指数较接近。【结论与意义】白花鬼针草是一种入侵能力很强的外来种。长的繁殖持续期和高种子产量是白花鬼针草和三叶鬼针草有别于本地种金盏银盘的重要入侵性状。本研究可为揭示三叶鬼针草和白花鬼针草的入侵机制和影响因素提供依据,并为入侵预测和控制提供基本资料。

Bionomics of two invasive weeds,Bidens alba and B.pilosa,and their native congeners grown under different nutrient levels

Background] Bidens alba and B.pilosa var.radiata（Compositae） are native weeds from tropical America,that have recently invaded roadside,cropland,waste ground etc.in South China,causing losses to local agriculture and the environment.Mechanisms facilitating their invasion are not well understood.We conducted comparisons between these two alien weeds and their native congener,aimed to know better the invasive ability and invasiveness.Method]Morphological and growth parameters,biomass and its allocation,the duration of reproductive phase and seed production per plant,as well as phenotypic plasticity index of B.alba and B.pilosa var.radiata were measured and compared to those of the native congener B.biternata,grown under different soil nutrient levels.Result]Most growth parameters except the duration of reproductive phase and seed production per plant had no significant difference between two alien weed and native weed under low soil nutrient level.At high soil nutrient level,the total leaf area as well as specific leaf area,leaf area ratio,duration of reproductive phase and seed production of B.alba were significantly higher than those of native B.biternata.However,the total leaf area,specific leaf area,total biomass and relative growth rate of alien weed B.pilosa var.radiata were significantly lower than those of B.biternata under high soil nutrient levels.The plasticity indexes of plant height,total leaf area,specific leaf area,total biomass,leaf area ratio,relative growth rate,mean leaf area ratio and seed production in B.alba were higher than those either in B.biternata and in B.pilosa var.radiata.Most plasticity indexes were similar between in B.pilosa var.radiata and in B.biternata.Conclusion and significance]B.alba was an alien weed with strong invasive ability.Long reproductive phase and high seed production in B.alba and B.pilosa var.radiata which were different from those in native weed B.biternata,were some of the important characters for invasiveness.This research provide evidence for revealing the invasive mechanisms and influence factors of B.alba and B.pilosa var.radiata,as well as provided basic data for prediction and control of invasions.