Time And Mechanism Of Embryo Abortion In Some Seedless Grapevine Cultivars To Rescue Their Embryo

Breeding new seedless table grapes requires application of embryo rescue technique. For successful application of this technique, it would be necessary to get enough information about anatomical and cytological phenomena occurs in certain time inside ovule after fertilization. To do so, this research work was conducted in 1998 in Horticultural Research Station in Karaj. Samples were collected at 2, 21, 35 and 45 days after flowering from 20 years old grapevines of five seedless cvs, i.e. White seedless, Red Seedless, Askary, Yaghooti and Green Keshmeshi. Samples were fixed in FPA50 and later ovules were dissected out, dehydrated, embedded and eventually serially sectioned longitudinaly at 5f.Lmthickness by ultra-microtome, stained with PAS method and were observed by field optics. Results showed that in all cvs, fertilization had been taken place in more than 50% of ovules, but not in all, due to their abnormal development. Zygote and free nuclear endosperm were formed. However, in some cvs e.g. Red seedless, zygote never get divided and degenerated before 21 days. In White seedless and Yaghooti few percent of zygotes could divide several times and produced few cells pro-embryo. In cv. Yaghooti, pro-embryo could develop by five weeks while in White seedless, pro-embryo could develop even by six weeks and then were degenerated. In cultivars such as Askary and Green Keshmeshi, higher number of pro-embryo could develop by 45 days. According to the results, embryo resuce should have been done before three weeks in cv. Red seedless, before five weeks in cv. Yaghooti and about six weeks in cvs White seedless, Askary and Green Keshmeshi.