Genetic diversity is important for crop improvement. An experiment was carried out at Merowe Research Station, Northern state of Sudan, during two consecutive winter seasons 2013/14 and 2014/15 to estimate the phenotypic and genotypic coefficients of variations, heritability in broad sense, genetic advance and genetic advance as percentage of the mean for yield and other growth attributes in twenty four bread wheat genotypes. A randomized complete block design with three replicates was used. Observations were recorded on days to 50% heading, days to 90% maturity, plant height (cm), number of spikes per m2 , number of grains per spike, 1000 - grain weight (g), harvest index (%) and grain yield (kg ha-1). Analysis of variance showed highly significant differences among the genotypes for all the characters studied. The earliest maturing genotype combined over two seasons (85 days) was entry no. 22 whereas the latest one (95 days) was the cultivar El Nielain. The results obtained indicated that the entries no.23,21, 17 and 18 gave significantly out – yielded than the standard checks except Imam with average yield advantage over the check Wadi El Neel amounting to 17.9%, 16.6%, 15.3% and 14.1%, respectively. The magnitudes of phenotypic coefficient of variance (PCV) were higher than genotypic coefficient of variance (GCV) indicating the influence of environment on genotypes. The estimates of genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were higher for number of spikes per m2, plant height and number of grains per spike. The remaining traits recorded moderate to low PCV and GCV estimates. Broad sense heritability (h²) estimates for various traits ranged from 25.3% to 80.7%. High heritability combined with high genetic advance as percent of mean observed for days to 50% heading, plant height and 1000 -grain weight, showed that these characters were controlled by additive gene effects and selection for genetic improvement for this traits would be effective.

Keywords: bread wheat, genetic variability, heritability, genetic advance, grain yield.