Genetical Studies on the Panicle Formation in Rice : I. Analysis of Component Characters of Panicle Density

Using 18 strains, ranging from lax to dense panicle type, the principal component analysis was performed to elucidate the correlations among 17 characters relating to the panicle density. The first principal component extracted from the principal component analysis for whole strains, appeared to correspond to a number factor, and the second to a length factor. However, it was fcund that the flrst principal component extracted from the analysis for nine lax panicle type strains, was considered to be a number and length factor, being identical with the two principal components in whole strains. Furthermore, the first principal component, interpretable as a number factor, in the analysis for whole strains was resolved into the first three principal components in the analysis for six dense panicle type ones. In the scatter diagram fcr the related characters of panicle density, 18 strains could be classified into seven groups, each distinguishable on the basis of difference in the pattern of panicle formation. The result demonstrated that both the lax and dense panicle genes had manifold effects on the component characters of panicle density, thereby causing the large variation in the correlations among these component characters.