‘平核無’未熟種子の発育不全について

Abstract

This work was carried out to clarify the relationships between parthenocarpy and seed abortion in seedless Japanese persimmon, cv. Hiratanenashi.1. Incomplete embryo-sacs, oblong or swollen types, were found abundantly in ovules of ‘Hiratanenashi’ at anthesis.2. Ovules in the parthenocarpic and pollinated fruit continued to develop until 60d after anthesis; however, the size of young seeds in pollinated fruits varied from 3mm to 20mm length.3. All ovules in parthenocarpic fruit and the majority of young seeds in pollinated fruit at both 30 and 60d after anthesis had a part of embryo-sac cavity filled with densely clustered tissues called “bar tissue”, staining with fuchsine acid, instead of embryos. “Bar tissue” surrounding the micropyle to chalazal region may originate from dividing inner integuments tightly investing the nucellus.4. Some ovules in pollinated fruit contained complete cellular endosperm even at the beginning of its formation, and most of them were found a little later to contain collapsed endosperm due to the abnormal division of cells. Therefore, it seems likely that the embryo may cease growth as a result of the degeneration of endosperm.5. “Bar tissue” in the ovules seems to operate instead of embryo for fruit growth at early stages in parthenocarpic ‘Hiratanenashi’.