植物园迁地保护环境下纹瓣兰的繁殖生物学研究

Reproductive Biology of Cymbidium aloifolium (Orchidaceae) Under ex situ Conservation in Botanical Garden

摘要:

深入了解濒危物种的繁殖特性，能为物种制定有效保护策略提供科学依据。于2022和2023年对中国科学院西双版纳热带植物园迁地保存的纹瓣兰(Cymbidium aloifolium)的繁殖生物学特征进行了观察和研究，主要包括开花物候、繁育系统、花部形态特征、昆虫传粉特征以及花的挥发性成分等。结果表明，纹瓣兰的盛花期在4月中旬，单花花期7 d；群体花期约为36 d。花粉活力在开花第1天时最高，约为47.15%，之后呈下降趋势。柱头在整个单花期一直具可授性，开花第2天可授性最强。人工授粉实验表明纹瓣兰自交亲和，不存在无融合生殖和自动自花授粉，繁育系统属于兼性异交繁育并依赖传粉者，自然结实率较低为6.9%。唇瓣的先端和基部的表皮细胞分别为锥形和指状突起，基部的指状突起细胞外附着有油脂颗粒，可能是传粉者的报酬。药帽黄色，其表皮细胞为锥形细胞，能够反射光线，可能起到吸引昆虫的作用，中华蜜蜂(Apis cerana)是纹瓣兰唯一的有效传粉昆虫。纹瓣兰的挥发性气味中(E)-乙酸-2-癸烯-1-醇酯含量最高。因此，纹瓣兰的花部结构与传粉昆虫具有显著的适应性。

Abstract:

Effective conservation strategies require an in-depth understanding of reproductive characteristics of plants. The reproductive biology of Cymbidium aloifolium was investigated in Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences in 2022 and 2023, including flowering phenology, breeding system, flower morphology, pollination characteristics and flower volatile components. The results showed that C. aloifolium flowers began to bloom during mid-April. An individual flower and the population of C. aloifolium lasted 7 and 36 days, respectively. The pollen viability peaked at 47.15% on the first day of flowering, and then decreased. The stigma remained receptive throughout the single flowering period, reaching peak on the second day. The breeding system was facultative outcross breeding and dependent on pollinators, and the natural seed setting rate was 6.9%. The epidermal cells at the apex of the labellum and at the base of the labellum were conical and fingerlike protuberances, respectively. The fingerlike protuberances at the base had oil particles attached outside the cells, which might be the reward of pollinators. The yellow cap had cone-shaped cells that reflect light and may attract insects. Apis cerana was the only effective pollinator ofC. aloifolium. The content of (E)-2-decenyl acetate was the higest in the floral volatile odor of C. aloifolium. Therefore, it was suggested that the floral structure of C. aloifolium had significant adaptability to pollinators.