青藏高原东部橐吾属三种植物的繁育系统

The breeding system of three species of genus Ligularia in the east of Qinghai-Tibet Plateau

关键词:  箭叶橐吾  掌叶橐吾  黄帚橐吾  毒杂草  繁育系统  生态对策

Key words:  Ligularia sagitta  L.przewalskii  L.virgaurea  poisonous weeds  breeding system  ecological strategy

摘要:

研究青藏高原东缘分布的箭叶橐吾、黄帚橐吾和掌叶橐吾的繁育系统,箭叶橐吾和黄帚橐吾各自居群中有性生殖和克隆繁殖的权衡关系,分析三种植物的的克隆繁殖与生态适应,探讨橐吾属植物对高寒环境胁迫条件下的适应与进化。结果显示三种橐吾的花果期在6月中旬到10月初,花序为头状花序组成的总状排列。三种橐吾的杂交指数(OCI)均为4,繁育系统以远交为主、部分自交亲和、虫媒、需要传粉者; 影响有性生殖成功的因素除昆虫侵食以外,黄帚橐吾和箭叶橐吾低的结实率主要原因是传粉媒介限制。限制结实的主要因素是高寒多风的环境限制了昆虫的活动,访花昆虫数量减少,从而使花粉转移效率降低,导致了低的结实率。植物采取的适应对策:大量开花,延长雌雄配子体的功能期和传粉媒介的泛化等,可见三种橐吾有性生殖的潜力依然很大。箭叶橐吾和黄帚橐吾在自然条件下主要进行有性生殖,在保护草场时,应针对其有性生殖器官采取措施。

Abstract:

In this thesis,the breeding system and reproductive strategies of the three species were observed and analysed. The adaptation and evolution of the genus Ligularia under the condition of psychro-environment were discussed. The result showed that the flowering and fruiting periods of the three species were from mid-June to the beginning of October,and their inflorescences were racemose arrangement with capitulum. The outcrossing index were 4 in the all three species,the breeding system was given priority to outcrossing,part self-compatibility,insects pollinator-dependent. The main factors effecting the success of sexual reproduction were pollinators scarcity and insects infection. The primary factor to limit seed setting was the windy psychro-environment which limits the activities of insects,leading to the insect number to visited flowers decreased. All these factors induced the low setting percentage. But the plants didn't accept this fact passively,instead they took active strategies of adaptability,such as mass blossom,prolonging the functional period of female and male gametophyte,and generalization of pollen medium. Therefore,the potential of sexual reproduction in the three species was still very great. Under natural conditions,the clonal growing rhizomes of L.sagitta and L.virgaurea were suppressed due to interspecific competitions on the grassland,therefore the reproduction of the two plants mainly dependented on seeds. This fact suggests,we should aim at sexual reproductive organs in management of the two weeds,we also need to pay more attention to ecological recovery on the degenerating grassland to prevent land form further desertification.