入侵植物剑叶金鸡菊的繁殖特征及其与入侵性之间的关系

入侵植物剑叶金鸡菊(Coreopsis lanceolata)既可进行有性繁殖,又能进行克隆繁殖,其繁殖特征可能对其入侵性具有重要影响,然而目前相关研究较少。通过观测剑叶金鸡菊的花序开花动态、交配系统、种子萌发特性等有性繁殖特征及克隆繁殖特征,研究了上述繁殖特性及其与入侵性之间的关系。结果表明,剑叶金鸡菊每年4月下旬开始现蕾,5–11月为花果期。单个花序的花期为5–6天,至果实成熟开裂约18天。单个花序自交及同株异花授粉不亲和,为异株异花授粉的异交型,其花粉-胚珠比(P/O比)为103549.40±7162.44。花序高花粉活力及本地蜂传粉行为保障了花粉资源,因而结实率高达12000粒.株–1。自然条件下其种子的萌发率高达50%以上,且2–3天即可萌发。剑叶金鸡菊克隆繁殖能力非常强,整个生长季节均可见从根蘖长出的密集型克隆分株,8月下旬开始出现游击型克隆生长,通过密集型和游击型克隆生长,剑叶金鸡菊排斥其他物种形成单优种群。上述研究结果说明,剑叶金鸡菊的入侵性与其繁殖特征密切相关。

Reproductive traits associated with invasiveness in Coreopsis lanceolata

Aims The invasive plant Coreopsis lanceolata can reproduce sexually and clonally, but the relative importance of these remains largely unknown. Our objective was to determine if reproductive characteristics affect the invasiveness of C. lanceolata. Methods We observed the flowering dynamics of inflorescence, self compatibility, germination traits of seed and clonal reproductive traits of C. lanceolata. Important findings Most C. lanceolata flowered and fruited between April and November. The florescence of a single capitulum persisted approximately 5 to 6 days, and the fruits matured after 18 days. Bagged capitula showed there were no seed set in single capitulum, and they were geitonogamous, which indicated self-incompatibility. The pollen-ovule (P/O) ratio was 103 549.40 ± 7 162.44. There was high pollen viability during flowering, and pollinator movement ensured endogamy, which improved the rate of out-crossing. Under natural conditions, the germination percentage is >50%, and germination occurs within 2–3 days. Coreopsis lanceolata has strong asexual capacity; there were many phalanx ramets from roots during the growing season, and the guerrilla ramets only occurred beginning in the last ten days of August, which is beneficial to C. lanceolata in excluding other species and forming mono-culture populations. These results suggest that the invasiveness of C. lanceolata is closely related to its reproductive traits.