Abstract:
Sesame is an annual oilseed plant, and indigenous, as evidenced with the presence of wild relatives, to Ethiopia. Despite immense economic importance and genetic resource, the report related to agronomical important traits is limited to very few populations. Thus, the current study was conducted to assess the genetic variability and association in yield, yield related traits and oil content of 36 Ethiopian sesame genotypes. The study was conducted at Babile and Dire Dawa, eastern Ethiopia, in 6x6 triple lattice designs in 2018 main cropping season. Significant difference among genotypes was found for most of the traits at both locations. Test locations had significant influence on all studied traits, except on capsule bearing zone. Seed yield ha-1 varied significantly between genotypes in the range of 261.9 to 586.9.1 kg with a mean of 422.4 kg at Babile while at Dire Dawa, the mean performance of genotypes for seed yield ha-1 ranged from 348.3 to 1232.5 kg with a mean of 792.3 kg. The mean performance of genotypes for oil content ranged from 40.6% to 55.1% with a mean of 51% oil content at Babile while at Dire Dawa, it ranged from 49% to 52.5% oil content with a mean of 51.2%. High phenotypic coefficient of variations (PCV) values were noticed for seed yield ha-1 , capsules plant-1 and thousand seed weights at Babile, and for seed yield ha-1 , seed plant-1 and number of primary branches at Dire Dawa. High genotypic coefficient of variations ( GCV) values were also recorded for seed yield ha-1 and thousand seed weight at Babile, and for seed yield ha-1 and seed plant- 1 at Dire Dawa. High heritability coupled with high genetic advance were estimated for seed yield ha-1 , capsules plant-1 , seed plant-1 and thousand seed weight at both locations indicating that selection for these traits would be very effective. Correlation and path analysis revealed that the characters viz., seed plant-1 , number of capsules plant-1 , seeds capsule-1 , thousands seed weight and number of primary branches have positive direct association along with significant positive correlation with seed yield per hectare. However, oil content exhibited positive non-significant association with seed yield per hectare. Therefore, these characters can be considered as a criterion for improving seed yield in breeding programs of sesame. The principal component analysis (PCA) tested across locations revealed five principal components accounted 87% of the total variation with traits of number of primary branch, plant height, seed yield, days to maturity, number of capsules/plant, capsule filling period and thousands seed weights were among the most important traits, which accounted for the phenotypic variation expressed in these genotypes. Cluster analysis categorized the genotypes into four major clusters and the dendrogram showed that clusters I, II, III and IV had 28, 1, 5 and 2 number of genotypes respectively. In conclusion, genetic variability exists in the studied genotypes, which can be used in the subsequent sesame improvement program