腊梅的受精作用及胚胎发生

腊梅 (Chimonanthuspraecox)花两性 ,离心皮雌蕊着生在杯状花托上 ,柱头线形 ,干性。花粉经昆虫传播 ,落在柱头上 1d后萌发 ,第 8d从珠孔进入 ,第 1 4d左右完成双受精 ,为珠孔受精。胚乳为核型胚乳 ;初生胚乳核经短暂休眠进行核分裂 ,位于合点端的游离核首先形成细胞 ,并从合点向珠孔端细胞化 ,第 37d胚乳充满整个囊腔。合子经过近 2周的休眠后开始分裂 ,随着胚的发育 ,大部分胚乳降解 ,为胚的发育提供营养。合点端的胚乳细胞则侵入合点珠心组织 ,为胚进一步发育提供营养。其胚胎发生为柳叶菜型。

The Fertilization and Embryogenesis of Chimonanthus praecox Link.

The process of fertilization and embryogenesis of Chimonathus praecox Link. was observed. The results showed that the pollen started to germinate one day after the pollination. The pollen tube penetrated through the style canal and reached chalaza in about 6 days. The tube extended slowly along the ovule towards the micropyle and entered the embryo sac in another 2 days. Afterwards, two sperms were discharged. One fused with the egg cell and the other with the central cell. Observations on the material of 14 days after the pollination showed that the double fertilization had finished. After a short phase of dormancy, the primary endosperm nucleus underwent free nuclear division. The free nuclei of the antipodal part became cellular at first. About 37 days later, the embryo sac was filled with cellular endosperm. So it belongs to the nuclear type. Before the development of the embryo, the zygote went through a dormant period lasting about two weeks. With the embryo development, most of the endosperm degenerated, and the cells near chalaza entered the chalaza, digested it and further nourished the embryo. At maturity of the seed, the endosperm remained in a rodlike structure around the embryo. The embryogenesis belongs to Oragrad type.