米の胚乳発達に関する組織形態学的研究 : 第9報 外国稲品種の胚乳の形状と細胞数について

抄録

In the cases of whole test sample varieties, the number of cell layers has a close proportional relationship to the length of longitudinal diameter of the endosperm. Such proportional relationship is also observed, though somewhat less clearly than in the case of longitudinal diameter, in the cases of the dorso-ventral (breadth) and lateral (thickness) diameters of the endosperm, respectively. The number of cell layers and the length of longitudinal diameter show a remarkably varietal difference, and they are in inverse proportion to the number of cell layers and the length of breadth and thickness. The whole number of endosperm cells has no proportional relationship in general to the length of longitudinal diameter (or number of cell layers), except for very long endosperm varieties. The whole number of endosperm cells shows a high correlation to the 'size' which is represented by the product of longitudinal, dorso-ventral and lateral diameters, but it does not show any definite correlation to the 'shape' which is represented by the ratio between longitudinal and dorso-ventral diameters. In general, varieties distributed in the low latitude region, especially indica rice varieties which are cultivated preyalently maintly in India, etd. are long and thin in endosperm shape, small in size (volume), and less in number of cells. On the other hand, varieties distributed in high latitude regions, irrespective of North-east Asian or European areas, are shorter and thicker in endosperm shape, medium in size, and medium in the number of cells as well. In Africa and in a part of Europe, most of the varieties show a tendency to remarkably long and thin endosperm shape, very large size and to remarkably large number of cells. In the respective parts in these regions, it is noticed that the varietal differences in endosperm size, shape and number of cells are almost insignificant. However, only in the cases of varieties prevalent in Pacific island areas in South-eastern Asia, it seems to form exceptions, where it shows significantly great varietal differences in size, shape and in number of cells. It can be made clear that Japanese varieties' endosperm belongs to the shortest type in shape and to medium type in size because of their large thickness, thus these are grouped into the medium varieties in the number of cells.