Observations On The Sexual Process Of Tetraploid Grape And Its Hybrid

Artificial inducing autotetraploid grape Muscat Hamburg, tetraploid grape hybrid Kyoho and their hybrid 'Juniei'were employed to study the relationship between sexual process and fruit growth, as well as other property in tetraploid grapes. The sexual process observations include the pollen and the female gametophyte development, growth dynamic of pollen tubes in ovary after pollination and embryo, endosperm development. The results are summarized as follows: tin the polygonum embryo sac of tetraploid grape , megaspore telrad arranged in straight line. Megaspore in the chalaza developed embryo sac. In the mature embryo sac, two endosperm nuclei neared each other and merged secondary nuclei. 2.The embryo sac mother cell took place simultaneously with the pollen mother cell. The female gametophyte had a great effect on berry set and fntit quality. Autotetraploid grape Muscat Hamburg had poor ratio of embryo sac and produced parthenocarpy easily, so it had seedless fruit berries. But hybrid 'Jumei' embryo sac developed well relativly. 3.The cleistogamy existed in all tested tetraploid grape varieties. Kyoho and Jumei cleistogamy took place earlier than tetraploid Muscat Hamburg.Tetraploid hybrid Kyoho and Jumei?s pollen tube fluorescent were strong, which indicated that nutriments were rich in it and can complete double fertilization well. Kyoho showed high percentage morphology abnormalities of ovules and its pollen tube grew slowly. This partly explained some causes of shedding and berry dropping in Kyoho. 4.The developing process of the embryo and endosperm was consistent in different tetraploid grapes. If endosperm degenerated, embryo ceased to develop and 41 ovule was degraded accordingly. So seedless berry produced or berry shedding took place. 5.There were close relationship between embryo and endosperm development with its fruit growth in all tested varieties. With embryo and endosperm developing, growth proceeding of the fruit was rapid and growth of the grape fruit is at the first stage, that is, at the growth stage (The development of the embryo and endosperm can promote the fruit growth). 6.The seed number in one berry was greatly correlated to the fruit peculiarity. The more seeds one berry had, the bigger one berry was. Jumei inherited the good qulity of its parents, and had evident heterosis.So it is worth popularization. These results suggested that we could use heterosis of tetraploid grape hybrid by selecting most suitable parents together with suitable cultare and manage measures to ensure the normal development of embryo and endosperm as well as promote rapid growth in peak stage of tetraploid grape fruit development.