Abstract:
Continuous identification of the best genotypes that have wider genetic base, capable of
producing better yield under a wide range of agro-climatic conditions and stresses increases
production and productivity. Forty nine bread wheat genotypes were evaluated for 12 traits in
simple lattice design at Jamma and Geregera to determine the extent of genetic variation and
character association among grain yield and its related traits. Mean squares of the traits studied
showed statistically significant differences among the genotypes listed (P< 0.01), indicating the
presence of adequate variability. Maximum values of genotypic coefficient of variation were
recorded for spike length (8.66%), number of productive tillers (8.4%), number of grains per
spike (6.4%) and thousand seed weight (6.15%), whereas better value of phenotypic coefficient
of variation were recorded for productive tillers, grain yield, spike length and harvest index with
values of (13.3%, 11.35%, 10.3% and 9%), respectively. Heritability ranged from 29.1% for
grain yield to 82% for days to heading. Relatively high genetic advance as percent of mean was
obtained for spike length, productive tillers, number of grains per spike, thousand seed weight,
heading date and plant height with values of (14.9%, 10.6%, 10%, 10%, 9.7%, and 9%),
respectively. Grain yield had strong and positive genotypic correlation with harvest index
(0.731), biological yield (0.617), thousand seed weight (0.395), plant height (384) and
productive tillers (0.366). Path analysis indicated maximum positive direct effect obtained
between grain yield and harvest index (0.731) and also grain yield and biological yield (0.731).
The first five principal components, with eigenvalue greater than one, accounted for 80.4% of
the total variation. Based on the average linkage cluster analysis, the 49 genotypes were
classified into six clusters; indicating the genotypes were divergent. Thus, crossing program
between members of cluster I with cluster III, and cluster II with III, and IV could possibly
resulted in heterosis in the F1, and a great deal of variability in the F2. Plant selection based on
plant height, higher number of grains per spikes, thousand seed weight, biological yield and
higher harvest index will be most effective for future wheat yield improvement program.
