Abstract:

The breeding system of an endangered dioecious species, Woonyoungia septentrionalis (Dandy) Law, was studied in two natural populations, the Mulun population and the Dahuangni population, in Guangxi Province, China from June 2001 to early September 2002. The female flowers from previously bagged buds were treated respectively with paper bags, net bags and hand pollination by comparing with natural pollination. The results showed that female flowers treated with paper bags, net bags, hand pollination, and natural pollination all set fruits and seeds, but there was great difference in their fruit set, seed set, pre-emergent reproductive success (PERS) and seed germination rate for two populations. In both populations, PERS of hand pollination and natural pollination were higher than those of paper bagged and net bagged treatments. Among them, PERS of hand pollination was the highest, and PERS of net bagged treatment was the lowest. Both sexual reproduction and apomixis occurred simultaneously in W. septentrionalis and seeds from both sexual and apomixis could germinate into seedlings. Therefore, the breeding system of W. septentrionalis belonged to facultative apomixis. The apomixis in Magnoliaceae was reported for the first time.

濒危植物焕镛木的兼性无融合生殖
曾庆文  张奠湘  高泽正  邢福武

(1.中国科学院华南植物研究所华南植物园，广州 510520；2.中国科学院昆明植物研究所，昆明 650204；
3.中国科学院华南植物研究所植物系统演化研究中心，广州 510650)

摘要： 2001~2002年连续两年在广西环江木论和广西罗城大黄泥的2个焕镛木（Woonyoungia septentrionalis(Dandy) Law）自然种群中, 对单性异株的濒危植物焕镛木进行繁育系统测定，对即将开花的雌花花蕾分别进行套袋、套网、人工授粉处理，并用自然授粉雌花作对照，其座果率和结实率统计结果表明：自然授粉、人工授粉、套袋和套网处理的花均能结实，但它们的座果率和结实率存在较大的差异。在两个种群中，人工授粉和自然授粉的总结实率(PERS)均比套袋和套网处理的高，其中人工授粉的最高，套网处理的最低。由此可见，焕镛木既能通过有性生殖方式结实，又能通过无融合生殖方式结实，而且这两种生殖方式获得的种子均能萌发成幼苗，由此断定，焕镛木的繁育系统为兼性无融合生殖。这是首次报道木兰科植物存在无融合生殖现象。
关键词： 焕镛木；繁育系统；兼性无融合生殖；无孢子生殖

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