Abstract
To clarify the characteristics and classify the dwarf strains in rice is important for recognition of mode of action ofdwarf genes and usefull for rice-breeding program. It was already found that there are different patterns in relative length of internodes in dwarf strains, and the pattern has been used for their classification. Recently, the principal component analysis has become to be noticed as a convenient method to analyse many characters simultaneously, and has been used by several workers for classification of the varieti es in order to look for usefull breeding materials or to investigate variations in plant types. The present study was attempted to clarify the variations of relationships arnong the lengths of panicle, upper five internodes and residue in the culrn and to classify many dwarf strains of rice using the principal component analysis. Materials used in the experiment were 76 dwarf, 22 normal, and 5 tall giant strains of rice. Pheno-ypic correlations between seven characters men-tioned above were analysed in all 103 strains as well as in 76 dwarf strains. Eigen value, eigen vector, and contribution percentage of each principal component, and standerdized score of each strain were calculated.
