Study On The Flower Bud Differentiation Of Osmanthus Fragrans Lour

This paper studied the process of floral bud differentiation of O. fragrans'Dangui', O. fragrans'Jingui', O. fragrans'Ziyingui'and O. fragrans'Sijigui', through outside observation light microscopy and scanning electronic microscopy. The results show that the process of bud differentiation began at mid-April and finished at late September, lasted more then six months. The process can be divided into 6 stages: the early differentiation stage, the involumcrum differentiation stage, the inflorescence primordium differentiation stage, the top flower perianth differentiation stage, the androecium differentiation stage and the gynoecium differentiation stage. From the process of floral bud differentiation, we looked that the differentiation speed has the slow-quick-slow characteristic. The androecium differentiation is earlier than gynoecium's. There is no difference for androecium development between four O.fragrans cultivars, Their stamens can develop into normal pollen sacs and ripe pollens. But there are obvious differences for gynoecium development between fertile O. fragrans'Ziyingui',O. fragrans'Jingui'and sterile O. fragrans'Dangui', O. fragrans'Sijigui'. When the pistil capel primordium of O. fragrans'Ziyingui'and O. fragrans'Jingui'appears firstly, it presents only one spot. Then it can develop into normal pistial which contains ovary, style and stigma. But the pistil carpel primordium of O. fragrans'Sijigui'and O. fragrans'Dangui'presents two spots when it appears firstly. With the development of flower buds, two spots could not healing, there is no ovule, style and stigma exist.Through floral bud differentiation studying, the author suggests that the abnormal pistil development of O. fragrans'Sijigui'and O. fragrans'Dangui'leads to its sterility. The cytokinesis of microspore mother cell of O. fragrans Lour. during meiosi is of simultaneous type. Its tetrasporophyte is tetrahedral .The mature pollen grain is of 2-cell type , and each has 3 germinal aperture. The development of anther wall follows the dicotyledonous type, composed of four layers, respectively epidermis, endothecium, middle layer and tapetum. Its tenuinucellate ovule has single integument. The archesporial cell lies under nucells epidermis, which developes into an functional megasprocyte. Megaspore tetrad is linear. the chalazal megaspore develops into an embryo sac of polygonum type. Hypostase and special integument tapetum exist in the ovule.