0023-6152

AA00247166

22556

Unrefereed

1) According to the morphological standpoint, the cultivated varieties of rice, including upland, lowland, glutinous, non-glutinous, long-glumed, scented, and red rice may be classfied into two different types: "Japonica" and "indica." 2) When cultivated in Japan Proper, all varieties of both types are highly self-fertile. This is also true of hybrids between varieties which belong to the same type. On the other hand, the hybrids between varieties belonging to the different types (i.e. "Japonica" and" Indica") are much less fertile. The process of pollen formation in hybrids within the same type and in those between the different types differs very much, in as much as it proceeds normally in the former, while in the latter it is extremely abnormal, the percentage of imperfect pollen grains being markedly great. By cytological examination, it is ascertained that, in the varieties belonging to the "Japonica" and" Indica" types, there is no difference in the number and behavior of their chromosomes, and in the course of pollen development. This hold true in the hybrids within the same type, but in the hybrids between the different types, the abnormaly of pollen is already manifested at the initial stage of its development following the division of the pollen mother-cell. 3) Rice in Japan Proper, Korea, Formosa, and China, belonging to the "Japonica" or "Indica" types can he clearly differentiated in different degrees by "Ring probe" for the precipitin reaction with "Absättigungsverfahren" in the test-tube and in the living body, generally speaking, the varieties, belonging to the "Japonica" type are closely related as are those, belonging to the "Indica" type, regardless of where they come from, while the varieties between the two types are fairly distinct from each other. 4) In short, the cultivated varieties of rice are to be classified into the" Japonica" and" Indica" types from the morphological standpoint. Moreover, judging from the degree of the sexual affinity, as well as serodiagnostic reaction, these two types are considered to be distantly related in descent. Therefore, the authors divide cultivated rice into two groups, regard them as subspecies, and propose to name one "Oryza sativa L. subsp. Indica KATO" and the other "Oryza sativa L. subsp. Japonica KATO." 5) As to the distribution of subspecies "Japonica" and" Indica" of cultivated rice we will find that the varieties indigenous to Japan Proper and Korea all belong to the one, and that those native to Formosa as well as those of Southern China, India, Java, and other countries mostly belong to the other. Although in Central China rice is, for the most part, of the "Indica" type, some varieties of the "Japonica" type are also found. The above investigation was carried on in the College of Agriculture, the Imperial University of Kyushu from 1923 to 1928. During the investigation, the authors received kind advices from Prof. Dr. R. KOKETSU, and also from Dr. T. MISAO in the serodiagnostic investigation. To them, the authors tender thanks most gratefully.