Browsing by Author "Mrimi, Geremiah A"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    A genetical analysis of yield and yield components in an 8-parent dialle cross of spring barley (HordeumVulgare, L.)
    (University of Dar es Salaam, 1979) Mrimi, Geremiah A
    An 8 x 8 dialled experiment involving parental F2 progenies was conducted in the field at the Uyole Agricultural Centre, Mbeya, Tanzania is the 1977-78 growing season. The aim was to obtain information on the magnitude and type of genetic variability for yield and its components, to estimate the magnitude of the various genetic components and to investigate the nature and magnitude of the correlations between yield and its components. Results indicate that additive and non-additive variation was present for all characters measured. The non-additive portion was greater than the additive portion for all characters except number of ears plant. Dominance was found for all characters and it was the main source of non-additive variation. Average degree of dominance for the characters measured varied from partial dominance to over dominance. Epistasia was found to be small, and it was detected in the characters plant height, number of grain per grain yield per plant and 1000 grain weight. Overall heterosis was found in the characters number of days to heading, plant height, ear length, grain yield per plant and 1000 grain weight. However, its magnitude and direction was specific to the cross.Heterosis for yield was generally associated with heterosis for the yield components, particularly number of ears per plant, member of grains per ear, earliness and plant height. Maternal effects were found for grain yield per plant and 1000 grain weight. Estimates of narrow sense heritability showed that all characters, except plan height, had values greater than 40%. Number of ears per plant showed the highest value (93.0%) while plant height had the lowest (24.3%). High yield per plant and high 1000 grain weight were associated with dominance, while lateness and high number of grains per ear were associated with recessiveness. Correlation studies showed that the characters number of ears per plant, plant height, ear length, grain yield per plant and 1000 grain weight were positively inter correlated. Number of grains per ear was negatively correlation with number of ears per plant and 1000 grain weight. Number of days to heading showed significant negative correlation with all characters except ear length and number of grains per ear. The implications of the results to barley improvement are discussed.