摘要
The embryogenesis, pollen germination, floral character and seed physiology of the endangered plant Manglietia aromatica Dandy were investigated. Based on this study, this species has very low seed set rate. The abortion rate of functional megaspores in all the ovules is 27.9%, the egg cell abortion rate of mature embryo sacs is up to 80%, and the germination rate of pollen grains is as low as nearly 0.01%. In addition, the floral structure appears to be another limited factor for the effective pollination of this species. The endangerment mechanism of this species seems to be comprehensive. Human's destroying actions are the direct factors that have made the population degenerate quickly; low reproductive ability and the destroyed environments are the main reasons that prevent the population from renovating and spreading. Therefore, the conservation measures suggested by this study are to research the breed technology, artificial population renovating, in situ conservation, and ex situ conservation.
针对香木莲 (ManglietiaaromaticaDandy)结籽率低以及野外实生苗稀少的现象 ,本文研究了香木莲雌配子体发育过程、花粉萌发力、开花生物学特性与种子结构的观察。结果表明 ,在雌配子体发育阶段存在以下退化现象 :1)从大孢子母细胞开始减数分裂到功能大孢子形成阶段 ,在此过程中珠心内的功能结构发生退化 ,功能大孢子未能正常形成 ,仅残留有退化痕迹 ,退化率为 2 7.9% ;2 )胚囊成熟时 ,受精前卵器细胞发生退化 ,退化率为 80 %。花粉萌发实验结果表明 ,在人工培养条件下具有正常萌发能力的花粉不足 0 .0 1%。这些都是香木莲结籽率低的重要原因。同时 ,香木莲的开花生物学特性限制了传粉的顺利进行。调查和研究的结果显示 ,人为的砍伐是造成香木莲种群急剧减少的直接原因 ;有性生殖障碍和生境破坏是制约香木莲种群更新的最主要因素。由此提出了对香木莲的拯救和保护对策 :就地保护 ;研究并推广繁育技术 ,进行种群重建 ;进行迁地保护 。
基金
中国科学院"西部之光"人才培养项目 ( 97C0 88M)
中国科学院知识创新工程项目 (I_46)~~
