脱水前后七叶树种子发芽率及胚根细胞超微结构的变化

对不同脱水程度的七叶树种子发芽率及种子胚根细胞超微结构进行了测定。结果表明:七叶树种子成熟脱落时含水量(DW)高达1.46 g/g,当含水量(DW)降低到1.07 g/g时,继续脱水就会对发芽率造成严重影响。同时成熟的七叶树种子胚根细胞分化完全,未经脱水的种胚细胞结构完整、清晰,细胞核大、居中,核膜、线粒体内嵴外膜、内质网、高尔基体亦比较清晰,液泡较小;脱水5 d后的种胚细胞中出现呈同心圆膜状结构的内质网;脱水7 d后同心圆膜状内质网增多、面积增大且出现多泡体,回水不能使其恢复,与种子发芽率急剧下降相对应。

Dehydration influence on the germination percentage and the ultrastructure of radicle cells of Aesculus chinensis seeds

The germination percentage and the ultrastructure of radical cells of Aesculus chinensis seeds which dehydrated for different days were studied in this paper.The result showed that the water content of mature A.chinensis seeds was high up to 1.46 g/g(DW).When water content was lower than 1.07 g/g(DW),further desiccation would decrease the germination percentage of seed dramatically.The radical cell of mature A.chinensis seeds were fully differentiated,and all cell organelles were shown up completely and clearly.The nucleus were large and situated in the middle of the cell.The nuclei membrane as well as the crista and outer membrane of mitochondrion were clear.The endoplasmic reticulum and golgi apparatus could be seen clearly,and the vacuoles were small.However,endoplasmic reticulum in the form of annulated lamellar structure was observed in cells after they were desiccated for 5 days and it became more and larger after desiccation for 7 days.The autophagic vacuoles in embryonic cell were observed after desiccation for 7 days.The annulated lamellar structure was not repaired after backwater.It is corresponding to the sharp decrease of seed germination percentage.