Studies on the Quantitative Inheritance (14) : A. Rice (Oryza sativa L. ). (d) Inheritance of the heading period and the quantitative function of the causal genes in its determinatioli. : (3) On the quantitative function of the genes Ea and Eb, and on the scale for heading period.

Abstract

1. The present paper is one of the studies which have been carried out in order to clarify the modes of quantitative inheritance in main crops from their breeding point of view. In this study the F₁ -F₄ generations from the three crosses (A) DairyutoX Nabeshima, (B) NabeshimaX Rozinto and (C) DairyutoXRozinto were used. The total number of lines and individuals observed were 243 and 19264 respectively. 2. Rozinto is a variety of early heading with short culm, while Nabeshima a medium heading type with medium culm and Dairyuto a late type with long culm (Table 1). 3. The conditions of growing plants were the same as those of the previous report (SYAKUDO, 1948-b), with the exception of sowing and transplanting dates. The heading period was measured by the number of days from the sowing to heading. The heading of a plant was indicated by the date on which the tops of its earliest ear began to emerge from the leaf-sheath.