Abstract: In order to find out the cause of low fertilization rate of Mopanshi, the pollen germination and pollen tube growth in style on persimmon cultivars Nishimurawase, Zenjimaru, Hanagosho and Mopanshi and the embryo sac development of Mopanshi were observed by means of fluorescence microscopy and with paraffin sections. The results obtained were as follows: ① The ratio of developed seeds (the number of developed seeds: the number of ovules) for Mopanshi crossed with three non-astringent cultivars was distinctly lower than that of self-pollinated three non-astringent cultivars; ② The pollen grains landed on stigma of Mopanshi and their germination rate were fewer than those of three non-astringent cultivars, which indicates that pollen grain germination was affected by female parent and Mopanshi stigma is unsuitable, comparatively for pollen to adhere, hydrate and germinate; ③ Compared with three non-astringent cultivars, there were very fewer Pollen tubes in Mopanshi style which were twisted and curled each other, and furthermore, the portion of pollen tube ceased elongating before they arrived at ovary, while as far as non-astringent cultivars were concerned, abundant pollen tubes could be observed in the ovary; ④ Diverse aberrant embryo sacs were found on Mopanshi, which directly or indirectly affected the normal process of fertilization. In conclusion, poor fertilization and aberrant embryo sac were the main causes of low seeded rate for 'Mopansh' persimmon.

Key words: persimmon, low fertilization rate, pollen tube, fluorescence, paraffin sections of embryo sac