GENETIC VARIABILITY AND TRAIT ASSOCIATIONS AMONG SORGHUM [SORGHUM BICOLOR (L.) MOENCH] GENOTYPES FOR YIELD AND YIELD RELATED TRAITS IN WEST HARARGHE, ETHIOPIA

Abstract

The study of genetic variability for key agro-morphological traits is crucial in sorghum breeding. Although, the national sorghum improvement programs have released a number of sorghum varieties for the highland areas of Ethiopia, the production and productivity is still low as compared to global potential (6 ton/ha ). Huge amount of sorghum germplasm exists in the country, but a little information is available on genetic variability, heritability and genetic advance for the studied germplasm. The current study was designed to generate information on genetic variability, to assess the associations among traits for yield and yield related traits and to identify traits that best explain genetic variation and to group the genotypes based on morphological traits. A total of 36 sorghum genotypes were evaluated in simple lattice design with two replications in 2021 main cropping season at Chiro and Hirna West Hararghe. Combined analysis of variance showed highly significant difference (p<0.01) among the genotypes for all studied traits. Genotypic coefficient of variation (GCV) ranged from 3% for leaf area to 29.65% for the harvest index, while phenotypic coefficient of variation (PCV) ranged from 3.2% for leaf area to 30.58% for the same trait, harvest index. Broad sense heritability ranged from 42% for panicle width to 99% for plant height. The maximum genetic advance (GA) was recorded for above the ground biomass (179) and minimum (1.54) fornumber of productive tillers. GAM ranged from 4.87% for leaf area to 61.19% for harvest index. Highly significant correlations of grain yield with harvest index (r = 0.93) panicle width (r=0.89), date to maturity (r=0.77), and thousand grain weight (r=0.59) were recorded at genotypic level. The cluster analysis grouped the genotypes under five clusters. The maximum inter cluster distance was observed between cluster III and cluster V (212.24). Therefore, the maximum amount of heterosis is expected from the crosses with parents belonging to cluster III and cluster V. In cluster mean analysis, cluster I manifested highest value for half of the studied traits and this cluster might be used as parental lines in sorghum improvement programs for target area. Principal component analysis revealed that the first seven principal components with eigenvalues greater than unity explained 75.00% of the total variation. Based on the current results, some promising genotypes exhibited relatively high performance for yield and yield related traits, which could be exploited for variety development in breeding program. However, to have a better recommendation further research is needed for more than a year across multi- location