Genetic variability and combining ability for quality parameters in Ethiopian wheat cultivars

English: Ethiopian cultivars and advanced lines of bread and durum wheat, originally selected for agronomic superiority, were studied for their grain quality parameters under different environments. Direct and indirect measures of quality were used to establish prediction equations of quality to recommend the minimum quality tests to be used in the breeding program of northwestern Ethiopia. • The HMW-GS of bread and durum wheat, the B-LMW and -ˠ-gliadin of durum wheat protein subunit compositions were identified and their associations with quality traits were studied. The combining ability, relative importance of additive and non-additive gene effects, genetic associations and inheritance of grain and quality traits were also investigated. Bread wheat • Genetic variability was detected among genotypes studied in most important quality traits. The loaf volume, which is the final product, ranged between 882.2 to 1010.8 cm3 with protein levels of 10.7-14.3%. The protein content levels of genotypes at the two Ethiopian sites were relatively lower. The mean mixing time increased (up to 5.5 min) with decreasing protein content of genotypes i.e. genotypes grown at the lowest protein site had the longest mixing time. • Among 15 independent grain yield and quality traits studied, flour protein content, SDS-sedimentation test, PIL ratio, gluten content and thousand grain weights explained 73 % of the variation in loaf volume under the higher protein (10-14 %) environment. The variation of mixograph development time due to protein content alone was 37 % at the lower protein environment. • Highly repeatable traits were PIL ratio, break flour yield, SDS-sedimentation volume, hardness index, mixing time and loaf volume ranging from 0.63 to 0.91. Loaf volume had a significant positive correlation with mixograph development time, SDS-sedimentation volume and alveograph gluten strength. • In a combining ability analysis, most studied traits showed significant additive gene effects. The ratio of GCA: SCA was 0.7 to 37. Heritability of mixograph development time (0.81), SDS-sedimentation volume (0.73), hardness index (0.68), grain weight (0.57) and flour yield (0.46) was higher than the rest of the traits. In studied sets of parents, utilizing additive genetic variance would be effective to improve mixing time, SDS-sedimentation volume, flour yield, vitreous kernels and thousand grain weights. • Eleven banding patterns of HMW glutenin subunits i.e., three at Glu-A 1, five at Glu- Bland two at Glu-D 1 were identified in Ethiopian bread wheat genotypes. The frequency of subunits 5+ 10, the high quality scoring alleles, was 78 %. Banding patterns showed significant differences in SDS-sedimentation volume, alveograph gluten strength, and loaf volume. Pattern 1, 7+8, 5+ 10gave the best results in the studied genotypes. Durum wheat The loaf volume ranged from 483-730 cm3 at protein levels of 10.1-12.5 %. Higher loaf volumes could be achieved by selecting for higher SDS-sedimentation volume and protein genotypes. Flour protein content, SDS-sedimentation volume and seed weight explained 69 % of the variation ofmixograph development time. • The frequency of the B-LMW glutenin and )I-gliadin (LMW-2/ ˠ45) subunit combination of proteins with better gluten strength and loaf volume was high in the studied genotypes. The highest bread volume (730 cm3) was recorded by line CD96486 possessing subunit combination of N/7+8 at Glu-AlIBj loci and LMW-2/ ˠ45 at Glu-A3 and Gli-Blloci, respectively.