摘要:寄生是生物有机体之间一种常见的互作关系，其有趣的生理、生态和进化问题日益受到关注与研究。以小红花寄生（Scurrula parasitica var.graciliflora）为研究对象，研究了该植物的开花物候、繁育系统、种子萌发特性及寄生关系的建立。结果表明：小红花寄生的开花高峰期为4月中下旬至5月下旬。花冠筒闭合期间与花冠筒开裂24 h后的花粉活力均> 90%，且两者之间没有显著差异（P > 0.05），但花冠筒开裂48 h之后的花粉活力≤ 70%。柱头可授性在花冠筒闭合期间显著高于花冠开裂之后（P < 0.05）。自然授粉的对照组和花蕾期套袋的实验组的座果率（分别是82.5%和83.1%）显著高于花开放之后的异花授粉的实验组的座果率（33.8%）（P < 0.05），而去除雄蕊的花则未能结实。小红花寄生的种子对脱水敏感，严重脱水显著降低种子萌发率。适宜的种子萌发温度为25℃和30/20℃。仅在桂花幼树的茎顶叶腋处获得了6.25%的寄生成功率，而其他部位的人工寄生均不成功。综合分析表明，两性花的小红花寄生依赖于前自交型的自花授粉；种子萌发表现出明显的温度偏好性，但对光照没有依赖性。人工寄生成功率显示，种子依附的寄主部位直接影响小红花寄生的幼苗与寄主寄生关系的建立。



Abstract:Parasitism, which is a common interaction between organisms in nature, has been increasingly brought into sharp focus and studied because of interesting questions regarding physiology, ecology and evolution. To elucidate crucial functional characteristics of reproductive ecology in Scurrula parasitica var. graciliflora (Loranthaceae), we focused on the investigation of flowering phenology, breeding system, seed germination characteristics and parasitic relationship establishment. The results showed that the flowering peak occurred between mid-late April and late May. There was no significant difference in pollen viability (>90%) between closed corolla tubes and 24-h open corolla tubes (P > 0.05), but the pollen viability (≤ 70%) in 48-h open corolla tubes was remarkably lower than that of the aforementioned tubes (P < 0.05). The stigma receptivity during corolla tube closure was significantly higher than during corolla tube dehiscence (P < 0.05). The fruit set rates of the flowers suffering from spontaneous pollination (i.e., control group), of the flowers bagged at the bud stage, and of the flowers treated by hand cross-pollination were 82.5%, 83.1%, and 33.8%, respectively. As expected, emasculation resulted in fruit-set failure. Ripened seeds were highly sensitive to desiccation, and severe dehydration significantly lowered germination percentages. Additionally, viable seeds that germinated well at 25℃ and 30/20℃, presenting obvious temperature preference. However, germination did not depend on light conditions. Seeds of this species were desiccation-sensitive, and serious water loss via drying significantly affected germination (P < 0.05). Yet 6.25% of the successful parasitism rate for the seeds was obtained in the axil close to the stem tip in the osmanthus saplings, other treatments were aborted for the seeds that were inoculated on stems, and leaves of both sweet-scented osmanthus trees (Osmanthus fragrans) and peach trees (Prunus persica). In conclusion, the study revealed that the breeding system of S. parasitica var. graciliflora is prior selfing and the germination temperature preference of desiccation-sensitive seeds, and that light was not a prerequisite for seed germination. Also, the data on parasitism suggested that the location where the seeds were attached was a core factor influencing parasitic linkage of seedlings with hosts for this parasitic species.





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