Division of Genetics, Indian Agricultural Research Institute, Delhi-12
*Presented at the 20th annual general meeting of the Indian Society of Agricultural Statistics held at Waltair in January, 1967.
The pattern of diversity in the genus Sorghum was analysed using the centroid method of factor analysis based on 10 to 12 characters in two groups of populations. One of them is representative of the spectrum of variation in the genus and the other comprised of high yielding grain types of Eu-sorghum.
Three factors were found to be adequate to account for most of the inter-correlations in both the genotypic and environmental correlation matrices.
The factor loadings on the variables were different in the two groups of populations indicating distinctly diverse causal differences under natural and human selection.
While the loadings were similar for genotypic and environmental correlations in natural populations, the differences were marked in the second group of selected populations. The data indicated that the environmental correlation matrix is appropriate for factor analysis in this material. The study revealed that the inclusion of variables influencing yield is more appropriate than yield itself in multivariate analysis.
The three factors in the group of natural populations were found to be growth, reproductive and panicle shape factors all known to be important components of fitness.
The results of factor analysis provided supplementary information on the diversity in this genus not available from the analysis of principal components and generalised distance and on the adequacy of the centroid method in biological investigations.
