Ovule development in seeded and seedless grapes

Female gametophyte and early embryo and endosperm development were examined in 3 seedless grape varieties, Himrod, Interlaken Seedless and N. Y. 15302, and in their seeded parent Ontario. A high proportion of functional embryo sacs was found at full bloom in all varieties. Fertilization occurred in all varieties. Precocious initiation of endosperm was observed with Himrod and extremely rapid development of endosperm was found with N. Y. 15302. Early degeneration of zygotes, failure of the zygotes to divide, and endosperm degeneration were observed in the seedless varieties with smallest seed remnants, Himrod and Interlaken Seedless. Imperfect development of the zygote and endosperm resulted in seed abortion (stenospermy) and seedless fruit (stenospermocarpy) in Himrod and Interlaken Seedless varieties.