鹅掌楸种子和胚胎发育的研究

STUDIES ON SEED DEVELOPMENT AND EMBRYOGENESIS IN LIRIODENDRON CHINENSE(HEMSL.)SARG.

应用控制授粉、软 X-射线法、常规石蜡制片法和荧光检测等手段,研究了鹅掌楸(Lirio-dendron chinense(Hemsl.)Sarg.胚胎发育和控制授粉与结籽率的相关性。控制授粉后2小时花粉萌发,6小时萌发率最高,柱头可授期持续30小时左右。花粉管借助于柱头毛之间的分泌物进入柱头沟,经花柱沟、珠孔塞和珠心冠原进入胚囊,行珠孔受精。授粉后2周,胚乳为2至3细胞厚的狭组织;第6周,胚乳充满胚囊腔,珠心随之解体殆尽;第7到8周,球形胚、心形胚发生;第14到16周,子叶形成;第22周种子或熟,胚乳丰富。单株自然授粉结籽率不足1%。控制授粉后,单个聚合果的最高结籽率可达39%,9个聚合果的平均结籽率为17.7%。

Embryogenesis,seed formation and the relationship between pollination and seeding rate were investigated by means of artificial pollination,X-ray analysis,routine paraffin-embedded sectioning technique and fluorescence assay.Pollen germinated two hours after artificial pollin- ation and the peak germination rate reached by six hours.The stigma vitality lasted about thirty hr The pollen tube grew into the stigma canal through the secretion between the stigma hairs, then passed the style canal,obturator and nucellar cap and finally reached the embryo sac where porogamy was conducted.Two weeks after artificial pollination,ab initio cellular endosperm was formed first as a narrow tissue of two to three cells in thickness,but six weeks later it filled the entire embryo sac,along with the disappearance of the nucellus.The spherical or cor- date-like embryo appeared during the seventh to the eighth week.The cotyledon was formed during the fourteenth to the sixteenth week.By the twenty-second weeks the seed became ma- tured,containing abundant endosperm,the seeding rate of an individual plant with natural pollination was less thah 1%;after artificial pollination,however the highest seeding rate of an individual fruit could reach 39%,the average rate of nine fruits being 17.7%.