加拿大一枝黄花繁殖性状对其入侵性的影响

Impact of reproductive traits on the invasive ability of Solidago canadensis L.

加拿大一枝黄花(Solidago canadensis L.)是一种危害严重的外来入侵植物.为探究其强入侵性,明确繁殖特征在种群迅速扩散蔓延过程中的作用机理,测定了加拿大一枝黄花的开花动态与杂交指数、花粉胚珠比、花粉活力、结实率、单花花期以及访花昆虫等有性繁殖特性.结果表明,加拿大一枝黄花为头状花序,单株植物的头状花序数量为3 199.50±459.64,花序的中央管状花数量为3.57±0.86,边缘舌状花数量为9.30±2.14,单株植物具有产生4万多粒种子的潜能;种群花期一般为10—11月,其中单个花序的平均花期为(10.90±2.93)d,管状花具有活性的花粉比为(93.56±8.99)%,随着开花时间的增加保持基本稳定;加拿大一枝黄花的杂交指数、花粉胚珠比以及自交亲和性等结果表明其为兼性异交植物,蜜蜂(Apis mellifora)是主要的传粉昆虫,在自然状态下加拿大一枝黄花的结实率高达78.51%.本研究从加拿大一枝黄花的繁殖特性较深入地分析了其种子量大和结实率高的原因,为研究加拿大一枝黄花的迅速扩散蔓延提供理论依据,也为其他菊科杂草种子的相关研究提供借鉴.

Solidago canadensis L. is one of the most important invasive weeds causing serious threats to native plants. In order to explore the flower characteristics and the reproductive system of S. canadensis natural populations, the flowering dynamics of inflorescence, the outcrossing index, the pollen-ovule ratio, the pollen viability, the seed set percentages, the florets flowering time and the visiting insects of S. canadensis L. were observed. Results showed that the average number of S. canadensis eapitulum per ramet was 3199. 50 ± 459.64, and the inflorescence central tubiform floret number was 3.57± 0.86, and the margin ligulate flower number was 9.30± 2. 14. The flowering time of population was from October to November, of which theaverage flowering period of a single inflorescence was （10. 90±2. 93） d. The average pollen viability of an individual inflorescence tubiform floret was （93.56±8.99）%, and did not decrease with the increasing of the flowering time. The outcrossing index of S. canadensis was 4 which indicated that it belonged to the cross- pollinate plants and needed pollinators during pollination. The pollen-ovule ratio was approximately 952.38± 361.62, indicating that the S. canadensis breeding system was facultative xenogamy. The most common floral visitors were bee species. These results suggest that the breeding system traits of S. canadensis have the potential to produce a huge amount of seed numbers, and can be carried away by wind for long distance dispersal. Thus, it increases the invasion potential of S. canadensis in China.