著者

萩屋 薫

出版者

一般社団法人 園芸学会

雑誌

園芸學會雜誌 (ISSN:00137626)

巻号頁・発行日

vol.27, no.1, pp.68-77, 1958

被引用文献数

2

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1. The present studies were carried out to investi-gate the heredity of the occurrence of pithy tissue, and that what correlation would be seen between its occurrence and the other physiological characters shown in the descendants of varietal hybrids in radish.<br> 2. When the growth of 20 F₁ hybrids crossed among 7 varieties, differing in easiness of the occur-rence of pithy tissue, was examined, it was found that the characteristic of the parents were fairly conspicuously inherited to F₁, in such characters as eaf number, leaf weight, root weight, T/R ratio, concentration of soluble matter in root sap, size of xylem parenchyma cell of root, content of starch in root, etc. In these cases, the greater part of the F₁ combinations surpassed the average of parents in many characters, but in comparing with the parents which retained heavier root weight, the F₁ combinations superior to the parents were not so many.<br> 3. Such a definite tendency as the F₁ is much easier or harder of the occurrence of pithy tissue than the parent varieties, could not be found, and in any combination the F₁ showed the resembling average value of the parents on its occurrence, and the influence of the vigor of hybrid on the occurrence of pithy tissue was not recognized.<br> 4. The occurrence of pithy tissue in varieties of F₁ and their parents was highly correlated with the concentration of soluble matter in root and size of xylem parenchyma cell of root, and slightly with content of starch in root, but there could not be found distinct correlation with root weight and T/R ratio. Those results indicate the possibility of breeding such lines as resistant to the occurrence of pithy tissue regardless early growth or rapid growth of corpulency of the root. For this purpose it must be suitable to use as the parents such va-rieties as &ldquo;Eichin&rdquo; and &ldquo;Tokinashi&rdquo; of which the capacity of assimilation of the top is great and the roots become fully replete.<br> 5. In the individual investigation of the growth of the F₂ which were produced from 3 combinations, in which the &ldquo;Eichin&rdquo; was crossed with other va-rieties differring in easiness of the occurrence of pithy tissue, a remarkable segregation of all cha-racters has been observed in every combination. The occurrence of pithy tissue of the individual F₂ was correlated with concentration of soluble matter, size of xylem parenchyma cell, and content of starch in root, but had no relation to the root weight or T/R ratio with one exception, as in F₁ generation.<br> 6. These facts reconfirmed the author's consider-ations, as it was described in the last report, that the occurrence of pithy tissue may be ascribed to, the abrupt corpulency which does not catch up the-fullness of roots, and also that its occurrence in F₁ and F₂ was highly correlated with the physiological-characters shown in the previous reports, even when the inheritance was utterly disturbed and genes were recombined by means of the varietal crossing as in this investigation.<br> 7. The inheritance of the occurrence of pithy-tissue may not be due to the existence of special-factors which directly determine its occurrence, but rather it may be indirectly inherited to the-descendants in accompany with the inheritance of many other characters such as responsible to pro-voke the unbalanced growth of the root corpulency, . as mentioned above.<br> 8. In breeding of resistant varieties to the occur-rence of pithy tissue, it is necessary to select the. resistant individuals from the young mother plants as accurately as possible as in case of selecting the-ones in their maturing stage. As an effective method to achieve this purpose it is suggested that selection of the individuals which contain high percentage of soluble matter