【作者】 陈士强；

【导师】 王忠；

【作者基本信息】 扬州大学 ， 植物学， 2007， 硕士

【摘要】 本实验以水稻、小麦及大麦为材料,用荧光显微镜观察花粉萌发及花粉管生长过程,用剪除柱头法观察其结实率,并采用光镜和电镜观察花后2 d内胚囊中极核的结构变化,得到如下结果:(1)水稻花粉粒落到柱头上后2 min即开始萌发,花粉管30 min后便可到达胚囊,花粉管的生长速率在柱头中最慢,花柱中次之,子房中最快;大麦,小麦授粉后3 min花粉粒开始萌发,花粉管生长动态与水稻相似。(2)花粉管到达胚囊珠孔端后总是从一个退化的助细胞中进入胚囊并释放两个精细胞,其中在水稻和小麦中发现该助细胞在授粉前即开始退化,而大麦中发现其在授粉后并在花粉管到达胚囊前退化。(3)精细胞进入胚囊以后,移动至退化助细胞的合点端,此处细胞壁薄或者缺少,使两个精细胞分别轻易进入卵细胞和中央细胞。虽然精核进入卵核附近较早,但其核的融合比精核与极核的融合完成的要晚。发现水稻授粉后2～4 h便发现极核已受精结束,而大麦小麦则需要3～5 h才能完成。(4)卵细胞受精以后要经过一段时间的“休眠期”,而极核受精以后很快就开始分裂形成游离核。(5)稻麦游离核较大,具有染色很深的的核仁,核周围细胞质浓厚,含有有丰富的细胞器,表现出活跃的状态。水稻游离核呈圆形,而麦类基本呈椭圆形。更多还原

【Abstract】 In this experiment, we studied the germination of pollen grain and the growth of pollen tube by fluorescence microscope, seed setting rate by removing stigma, and by light microscope and electron microscope observed the changes of polar nucleus in two days of rice, wheat and barley. The main results were as follows:(1) Rice pollen grain started to germinate two minutes after it reached the stigma. Half an hour later, the pollen tube reached the embryo sac, and it grew in stigma less slowly than grew in style and ovary. The pollen grain of wheat and barley started to germinate in three minutes, and the growing process of pollen tube was similar to rice’s.(2) After the pollen tube arrived at the base of the embryo sac, it would enter into it from a degenerated synergid and release two sperm cells. It was found that the synergid had degenerated before pollination in rice and wheat, while barley’s synergid degenerated after the embryo sac mutured but before pollen tube’s arrival.(3) After the sperm cells entered into embryo sac, they would move near the top of degenerated synergid where was of thin cell walls. So the two germ cells would enter into the egg cell and the central cell easily. Although the sperm nucleus came to the egg nucleus earlier, its nucleus fusion finished less slowly than that of the sperm nucleus and the polar nucleus. It was found that rice’s polar nucleus fertilized in 2～4 hours after pollination, while the polar nucleus fertilization finished in 3～5 hours.(4) After fertilization, zygote would undergo a period of dormancy, while the primary endosperm nucleus began to divide into free endosperm nuclei soon.(5) The free endosperm nucleus of rice, wheat and barley all was larger than other cell’s nucleus, and its nucleolus could be deeply stained. The free endosperm nucleus had heavy cytoplasm containing abundant organelles in active condition. The free endosperm nucleus of rice was nearly round, while wheat and barley’s was basically oval.更多还原