濒危植物大果木莲与中缅木莲的花部特征及繁育系统比较

Comparison of Floral Traits and Breeding System of Endangered Plant Manglietia grandis and Non-endangered Plant Manglietia hookeri

以非濒危种中缅木莲为对照,对其及濒危种大果木莲的花部结构进行了观察和测定,并采用花粉TTC染色、花粉萌发、杂交指数、人工套袋试验、花粉—胚珠比等方法,对二者的花部特征、繁育系统及花粉活力等进行了比较研究。结果表明:大果木莲花朵较大,花色艳丽,香味浓郁,适合虫媒传粉,其雌蕊群、雄蕊、花药都较对照大,而心皮数量、单花胚珠数量及雄蕊数量都较对照少15～31个、3～45粒、93～128个。其花粉—胚珠比为14285.98±4192.2,是对照种的2倍以上,远交程度较高,杂交指数为4。结合套袋试验结果可以确定该物种为异花授粉类型,不存在无融合生殖,部分自交亲和,需要传粉者;对照种亦为异花授粉类型,但自交亲和率较高。根据套袋试验及观察,该物种为虫媒传粉,对照种则有虫媒和风媒传粉2种方式。从生殖生物学方面来看,其繁育系统上的差异导致大果木莲生殖力较对照种低,可能只是大果木莲比中缅木莲濒危的原因之一。

An experiment was conducted to study the floral traits and breeding system of endangered species Manglietia grandis by TTC staining of pollen, pollen germination, out-crossing index, bagging test, pollen-ovule ratio using non-endangered species Manglietia hookeri Cubitt. et Smith. as control. Breeding system and pollen viability of the two plants were compared. Results show that M. grandis is suitable for insect pollination due to its big and brightly colored flowers with full-bodied flavor. The pistil base, stamen, and anther of M. grandis are bigger compared with the control, while the numbers of carpel, ovule of a single flower, and stamen are lower than those of the control species for 15~31, 3~45, 93~128 respectively. The pollen-ovule ratio of M. grandis is 14285.98±4192.2, which was two times higher than the control species, indicating a higher degree of cross. Out-crossing index of M. grandis is four. Bagging test results show that M. grandis is a cross-pollinated species without apomixis, which is partially self-compatible and needs pollinators. The control species is also a cross-pollinated species with a higher rate of self-compatible. Bagging experiment indicates that M. grandis is an insect pollinated species, while M. hookeri is a wind pollinated and insect pollinated one. As viewed from reproductive biology, the reproductive success rate of M. grandis is lower than that of M. grandis caused by the difference in their breeding system may only be one of the reasons led to M. grandis being endangered.