Genetic Variability and Association of Traits among Sorghum Genotypes [Sorghum bicolor (L.) Moench] Under Drought Stress Area

Drought is one of the most important factors that affect crop production worldwide and continues to be a challenge to plant breeders, despite many decades of research. Understanding the genetic variability among sorghum genotypes is the key objective to develop improved sorghum cultivars for drought-prone environments. The field experiment was conducted at Miesso during the 2021 main cropping season. A set of 72 sorghum genotypes advanced from a pedigree breeding approach was used in this study. The experiment was laid out using a Row-Column design with two replications. R statistical software was used to analyze the data. The analysis of variance indicated that there were significant variations among the tested genotypes for the studied traits. Genotypic and phenotypic coefficient of variation ranged from 0.56–23.88% and 0.66–28.99% respectively. Broad sense heritability ranged from 25.56–86.87% while genetic advance as a percent of mean ranged from 1.11–43.40%. Principal component analysis (PCA) revealed that five principal components with Eigenvalue greater than unity accounted for 74.1% of the total variation. Cluster analysis grouped the test genotypes into five clusters. Cluster I, II, III, IV, and V accounted for 41.667%, 6.944%, 26.389%, 16.667%, and 8.333% of the tested genotypes in that order. The highest intra-cluster distance was observed for cluster V whereas the maximum inter-cluster distance was observed between cluster IV and V. The lowest intra-cluster distance was observed for cluster III, whereas clusters I and III showed the lowest inter-cluster distance. The overall study revealed the presence of wide genetic variability among the studied sorghum genotypes in the study area where moisture stress is a critical problem for sorghum production.