外来入侵植物刺苍耳的繁殖生物学特性研究

Study on reproductive biology characteristics of invasive plant Xanthium spinosum L.

外来种在新栖息地种群建立的成功与否,其繁殖特性起到了决定性的作用。为了揭示外来入侵植物刺苍耳(Xanthium spinosum L.)的入侵机理,本研究测定了刺苍耳的开花物候、传粉媒介、柱头可授性、花粉活力、柱头表面积与花粉粒横截面积的比值、繁殖分配及交配系统等繁殖生物学特征。结果表明:(1)刺苍耳种群花期很长,雄花花期91 d,雌花花期100 d;(2)刺苍耳为风媒传粉植物,即便在风速为0.89 m/s的微风条件下,其花粉散播距离也可达到34 m;(3)柱头具有可授性的时间为11 d,1 d内花粉具有活力的时间为15 h;(4)柱头表面积与花粉粒横截面积的比值为742.08,有利于雌花柱头成功捕获空气中的花粉;(5)繁殖分配比例高达53%,说明该植物将超过半数的母体资源都用于投资繁殖产生种子;(6)刺苍耳既自交亲和,又可以异交结实,从而确保繁殖成功。本研究表明刺苍耳具有很强的有性繁殖能力,这可能是其成功入侵的重要原因之一。

The reproductive characteristics of exotic species play a decisive role in the population establishment in new habitats.In order to reveal the invasion mechanism of the invasive alien plant Xanthium spinosum L.,this study determined the breeding ecological characteristics,including flowering phenology,pollinating agent,stigma receptivity,pollen viability,ratio of stigma surface area to cross-sectional area of pollen grains,reproductive allocation,breeding system,etc.The results showed that:(1)The florescence of X.spinosum population was very long.The male florescence lasted 91 d,and the female florescence lasted 100 d.(2)X.spinosum was pollinated by wind,and the pollen dispersal distance could reach 34 m at a wind speed of 0.89 m/s.(3)The stigma receptive period was 11 days,and the pollen had vitality for 15 hours in one day.(4)The ratio of stigma surface area to maximum cross-sectional area of pollen grains was 742.08,which was conducive to the successful capture of pollen grains in the air by the stigma.(5)The proportion of reproductive allocation was as high as 53%,indicating that the plant uses more than half of the maternal resources for investment in reproduction to produce seeds.(6)The mixture of selfing and outcrossing assured the successful reproduction for X.spinosum.This study shows that X.spinosum has strong sexual reproductive capacity,which may be one of the important reasons for its successful invasion in the study area.