GENETIC VARIABILITY AND ASSOCIATIONS AMONG YIELD AND YIELD RELATED TRAITS IN ETHIOPIAN LINSEED (Linum usitatissimum L.) LANDRACES

Abstract

Assessment of genetic variability in crop species is one of the major activities of plant breeding which helps to design breeding methos.Keeping this in view, the present study was conducted to assess the genetic variability and character associations among yield and yield related traits in Ethiopian linseed genotypes.Fortiy nine linseed genotypess including four released varieties were evaluated in 7x7simple lattice design at Debre Berhan,North Shewa in 2018 main cropping season.The analysis of variance showed significant differences among the genotypes for all characters, except for number primary branches per plant and number of tillers per plant; indicating the existence of variability and potential for selection of genotypes for desirable traits.The phenotypic coefficient of variation ranged from 6.74% for days to maturity to 91.49% for oil yield ha-1, where as the genotypic coefficient of variation varied from 3.66 for oil content to 42.26% for number of secondary branches per plant.The estimated broad sense heritability ranged from 34.75% for oil yield ha-1 to 90.28% for seed yield ha-1.Similarly genetic advance as percent of mean ranged from 99.61 for number of secondary branches per plant to 7.55 for oil content.High heritability with high genetic advance was observed for number of secondary branches, plant height and number of capsules per plant.Seed yield ha-1 at phenotypic and genotypic level showed positive and significant correlations with oil yield ha-1,harvest index, number of secondary branches per plant,1000 seed weight and seed yield per plant at (P≤0.01).Oil yield ha-1 exhibited positive genotypic and phenotypic correlation with seed yield per plant, seed yield ha-1 and oil content at (P≤0.01).The path analysis showed that harvest index,1000 seed weight and oil yield ha-1exerted maximum positive direct effects on seed yield ha-1 at phenotypic level.However, seed yield per plant,oil content, and number of capsules per plant exerted negative direct effects on seed yield ha-1.Likewise harvest index,days to maturity, and number of secondary branches per plant exerted positive direct effect on seed yield ha-1 at genotypic level,while capsules per plant exerted negative direct effect on seed yield.Oil yield ha-1 at both phenotypic and genotypic levels was positively and directly influenced by seed yield per plant,seed yield ha-1and oil content;while negatively influenced via biological yield ha-1, days to maturity, number of secondary branches per plant and harvest index.The genetic distance for all possible pairs of 49 genotypes ranged from 2.08 to 11.1 with the mean, standard deviation and coefficient of variation of 5.25,1.35,and 25.69,respectively.The genotypes were grouped into eleven distinct clusters of which cluster II, VII and I were the largest cluster including 27(55.11%)genotypes together; while cluster XI,VIII and IX were solitary each constructed by one genotype.The first four principal component with Eigen values greater than one accounted for 61.94% of the total variation of the genotypes.Generally, this study showed the presence of variations among genotypes for measured traits with wide range of genetic distances that could allow selection and hybridizatio