中国沙棘(Hippophae rhamnoides L.ssp. sinensis Rousi)的开花特性及风媒传粉距离的检测

连续两年对雌雄异株的中国沙棘(Hippophae rhamnoides L.ssp. sinensis Rousi)的花期物候、开花式样进行了观察,检测了柱头可授性、花粉活力和花粉-胚珠比,并进行了人工授粉、套袋实验,检测结实率.结果显示中国沙棘风媒传粉发生在4月下旬或5月上旬,单花花期约7d;传粉盛期在第3天到第5天,柱头的可授性从第2天到第4天或第5天.中国沙棘花先叶开放、花小、无花冠、花药成熟时萼片从两个侧面的纵缝中裂开,形成有利于花粉散布的对流风洞.花粉活力和花粉-胚珠比都很高,具有典型的适应风媒传粉的花部特征和性状.中国沙棘花粉的传播距离受外界环境影响较大,通过重力玻片法检测可以看出,在风速小于3m/s时,主要集中在15～25m之间,当风速大于3m/s时,顺风向可超过85m以外.传粉效率对结实率的影响较大.

Determination of the wind pollination distances and flowering characteristics of Hippophae rhamnoides L.ssp. sinensis Rousi (Elaeagnaceae)

Chinese sea buckthorn is a dioecious shrub with wind-pollinated flowers. This work aimed to study the influence of flowering pattern on pollination, and the effect of pollination efficiency on fruit set percentage. During two successive years, we observed flowering phenology and patterns, and investigated pollen viability, stigma receptivity, pollen-ovule ratio (P/O), and fruit set percentage. The results showed that the pollination period stretched from April 20 to May 10. The blossom of a single flower could last 7 days, with a pollinating peak between the third and fifth day and the stigma-receptive stage between the second and fourth or fifth day. The flowers were small, without corolla and appeared before the leaves emerge. There were 2 sepals and 4 stamens in a male flower. When anther matured, two sepals split from both sides to form a wind tunnel, which made pollen shed easily. The flowering pattern and characteristics were typically adapted for wind pollination, with high pollen viability (70.8%) and remarkably high pollen-ovule ratio (7×105). The distances of pollen dispersal were significantly influenced by wind speed and other environmental factors. The pollen dispersed 15-25m at a wind speed of less than 3m/s, and the distance could exceed 85m when the wind speed was higher than 3m/s. Extreme bad weather could significantly reduce the efficiency of pollination and cause a low fruit set percentage.