贯叶连翘的开花动态与繁育系统研究

Floral biology and breeding system of Hypericum perforatum

关键词:  贯叶连翘  繁育系统  花粉活力  杂交指数  花粉-胚珠比  相对生殖成功率

Key words:  Hypericum perforatum  breeding systems  out crossing index  pollen viability  relative reproductive success

摘要:

野外观察贯叶连翘的开花进程和花部形态特征，运用花粉萌发、杂交指数、花粉-胚珠比等方法测定其繁育系统。结果显示：贯叶连翘雌雄异熟，柱头先花药成熟，雌雄蕊无明显异位。单花花期4～5 d。仅在开花当日有昆虫传粉，蜜蜂为主要传粉者。花粉在花药开裂1 h后活力最大，萌发率达40.10%，花粉在柱头萌发3 h后接近子房。根据杂交指数（OCI）推测其繁育系统属于异交，部分自交亲和，有时需要传粉者。花粉-胚珠比（P/O）则表明贯叶连翘的繁育系统为兼性异交。贯叶连翘结实率低，可能与花粉活力，花粉管的生长速度及花粉在柱头的竞争有关。

Abstract:

In order to understand the reproductive biology of Hypericum perforatum，the floral biology and breeding system were investigated in the present manuscript by means of the field observations on the flowering duration，pollen viability，out crossing index and pollen ovule ratio. The results showed that H.perforatum was protogynous，the female organ mature before male organ and there was no obvious herkogamy. A single flower lasted for 4 days. Pollinators visited only at the first day of flowers blooming and bees were the main pollinator. The pollen viability reached the highest one hour later after the anther splited(the viability of pollen was about 40.10%)，and pollen tube approached ovary three hours later. The out crossing index(OCI)was 3 or 4. According to criteria proposed by Dafni，H.perforatum was determined as outcrossing，partially self compatible，sometimes demanding for pollinators. The pollen ovule ratio(P/O)was approximately 591.5. H.perforatum was concurrently xenogamied by Cruden’s criterion. Possible reasons that relative reproductive success(RRS)rate of the species was only 7.88% may be lower pollen viability，the growth speed of pollen tube and competition of the pollen grains on stigmas.