二面交雜에 依한 水稻出穗期의 遺傳分析

Diallel Analysis on Days to Heading in Rice

Seven parent varieties and 21 F₁ hybrids from 7×7 partial diallel crosses were used as the materials, and genetic studies were carried out to obtain basic information of days to heading in rice breeding. Positive or negative heterosis were observed depending upon F₁ combinations. Average percentage of heterosis was shown in positive values, while average percentage of heterobeltiosis shown in negative values. Mean square values of General Combining Ability (GCA) were more greater than those of Specific Combining Ability (SCA) and the effects of GCA and SCA were differ from parent varieties and F₁ combinations. In the analysis of variance, the gene action of days to heading revealed that additive effects were more prevalent than dominance effects. In the analysis of parent-offspring covariance (Wr) and array variance (Vr), days to heading was exhibited by partial dominance. Kueiluai 8, Milyang 23 and Hsiangai-tsao 9 appeared to have many recessive genes of days to heading and this results were demonstrated in the standardized deviation graph. The degree of dominance on days to heading appeared to partial dominance with additive effects, and estimated heritabilities in the narrow sense as well as in the broad sense were very high (above 0.8) in F₁ generation.