<departmental bulletin paper>
ON THE AFFINITY OF RICE VARIETIES AS SHOWN BY THE FERTILITY OF HYBRID PLANTS'

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Abstract 1) According to the morphological standpoint of the plant, the cultivated varieties of rice may be classified in two different types : "Japonica" and "Indica." 2) Varieties of both types all have a hi...gh degree of self-fertility. This also true of hybrids resulting from varieties which belong to each type, that is, hybrids within the same type. On the other hand, the crosses of varieties of the "Japonica" type and those of the "Indica" type, namely the hybrids between the different types are very less fertile. 3) As to the formation of Pollen in hybrids w ithin the same type and in those between the different types, it is found very normal in the former, but in the latter it is extremely abnormal and the percentage of imperfect pollen grains is markedly great. 4) In the F2 generation , the degree of fertility of every strain within the same type was great, and almost alike to that of the parents or the F1 plants ; nevertheless, the fertility of the F2 plants from the hybrids between the different types was very low, deviation of the degree of their fertility being, however, very large. 5) All things considered, t h e cultivated varieties of rice can be classified into two types above named not only from the morphological standpoint, but also from the sexual affinity. These two types are, therefore, considered to be only distantly related in descent. 6) If we considered the dis t ribution of the "Japonica" and "Indica" types of cultivated rice, we shall find that the varieties native to Japan proper, Korea and Northern China 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. Though in Central China rice is, for the most part of the "Indica" type, some varieties of the "Japonica" type are also found.
1. 稻の栽培稻品種は水稻, 陸稻或は粳種, 糯種の差別に關せず, 地上部形態によりて, 日本型及び印度型の二群に區別せらる。2. 日本型及び印度型品種は總て高度の結實度を有し, 又兩型各々に屬する品種相互間の交雜によりて成れる雜種, 即ち同型間雜積に於ても同樣なるも, 日本型印度型兩型品種間の交互交雜による雜種即ち異型間雜種に於ては著しく不稔性を表はす。3. 同型間雜種並に異型間雜種に於ける花粉の形成は, 前者に於ては極めて正常なるも, 後者に於ては著しく異状を呈し, 不完全なる花粉粒著しく多し。4. F代に於ける各系統の結實度は, 同型間雜種に於ては親植物乃至F1植物と同樣にして總て大にして偏差小なるも, 異型間雜種に於ては種々の程度の結實度を示す個體に分離し, 偏差著しく大にして, 其の平均價は前者に比すれば小なり。5. 故に日本型品種相互並に印度型品種相互に於ては雜種和合の程度大なるも, 日本型及び印度型品種相互に於ては雜種和合の程度著しく小なり。6. 之を要するに栽培稻品種は形態上より見て日本型及び印度型に區別せられ, 而かも兩者は雜種和合の程度小なる點より見て, 系統上近縁ならざるものと認めらる。7. 栽培稻品種の日本型或は印度型に屬するものゝ分布状態を見れば, 日本内地及び朝鮮の在來稻は總て前者に屬し, 臺灣在來稻, 支那南部, 爪哇, 印度等に於けるものが主として後者に屬するものの如く, 支那中部に於ては主に印度型品種なるも, 幾分周本型品種の混在するを見る。
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Created Date 2012.03.02
Modified Date 2015.12.07