GENETIC VARIABILITY AND ASSOCIATION AMONG TRAITS IN SORGHUM [(Sorghum bicolor (L.) Moench)] GENOTYPES AT FEDIS, EASTERN ETHIOPIA

Abstract

Sorghum is an important food crop that is consumed by millions of people as a staple food source in arid and semi-arid areas of the developing world, especially Africa. It withstands hot and dry conditions better than most cultivated crops in Ethiopia. Sorghum is the most important crop for food security in Ethiopia's harsh conditions, where other food crops are difficult to grow. The experiment was conducted at Fedis Agricultural Research Center on station in 2022/23 main cropping season using 8x8 simple lattice designs. The study was initiated to determine the extent of genetic variation, heritability, and genetic advance in sorghum genotypes; to assess the associations among yield and yield related traits, and to determine the direct and indirect effects of traits on grain yield of sorghum genotypes. The analysis of variance revealed highly significant (P<0.01) differences among the studied sorghum genotypes for most of the traits except long smut, stay green and panicle exertion which had non-significant differences. The high GCV and PCV values were recorded for above-ground biomass yield. High broad-sense heritability associated with high genetic advance as a percentage of mean was observed for plant height, leaf area, and above ground biomass yield. Grain yield had highly significant and positive correlation with grain filling rate, above ground biomass yield, plant height, heads weight, panicle width, panicle exertion, number of leaves per plant, leaf length, leaf width and leaf area both at genotypic and phenotypic levels. Path coefficients analysis showed that grain filling rate had a very high positive direct effect on grain yield and it had a highly significant and positive correlation at both genotypic and phenotypic levels. The cluster analysis grouped the sorghum genotypes into five different clusters based on their dissimilar performance. Among the different clusters, the cluster size varied from 1 to 26. The maximum number of genotypes found in cluster II (26) while the minimum number of genotypes obtained in cluster V (1). The cluster distance ranged from 60.44 to 307.82 between clusters. The maximum inter-cluster distance was found between clusters IV and V (307.82) while the highest intra-cluster distance was observed in cluster I (35.07). The first five principal components (PCs), with Eigen value greater than one, contributed 70.1% of the total variation. The PC1 contributed the maximum towards the variability (31.1%) followed by PC2 (15.8%). In general, the present study showed the presence of considerable variability among the tested sorghum genotypes and the possibility of improving yield and other desirable traits through selection. The promising sorghum genotypes from the divergent clusters could be used in crossing programs to produce the maximum amount of heterosis in the sorghum breeding program.