抄録
1. In this work, the writers intend to make clear the modes of quantitative inheritance in main crops from the view point of breeding.For this object, ' a part of the hybrids of " NA BESHIMA" x "KAlRYO-AIKOKUHEN-DAIKO-KUGATA" was used namely-the F5-F7 generations from the F4No. 70 and F4No. 106 of the hlybrid. The total numbers of lines and individuals are 27.2 and 15244 respectively. 2. The conditions of cultivation are the same as those already described in the previous reports (SYAKUDO, 1948), excepting the dates of sowing and transplantation. The date of heading indicates the first day when the top of one ear emerged from the leaf-sheath. And the heading duration indicates the nunrber of days from sowing to.heading. 3. As the result of the progeny test, the genes E1, E2 and the dwarfish gene D1 determine the heading duration accumulatively. Ptobably the effect of E1 may be of perfect dominance, while that of E2 of inperfect dorrLinance. The gene-interactions are recognized b.etween E1 and E2, though their qualifying effects are neither additive nor multiplicative. 4. The qualifying values of the genes which indicate the medium type of heading duration are the same in the two years, but those of th.e genes which indicate the early and the late typ, es are not the same respectively. These differences seeni to be due to the difference of the daily mean temperature during the heading of each type. 5. The gene El for the heading duration seems to be the same as the gerne H2 for the culm height (SYAKUDO, et.all. 1952-b), while the gene E2 for the heading duration has no effect to the culm height.
