Associations between three proanthocyanidin-free genes and some important characteristics in barley (Hordeum vulgare L.)
Three lines, each including a different ant gene (ant 13, 17 and 18), were crossed to a common parent, the two-rowed malting cultivar Manley. The progenies were used to study the associations between these three ant genes and a number of agronomic and malting quality traits in two-rowed barley. Significant associations were found between the three ant genes and biomass, plant height, grain yield and kernel weight; between ant 13 and spike number, harvest index and days to heading; and between ant 18 and fertility. For all associations, except that between ant 13 and days to heading, the mean values for the Ant/Ant subpopulations were greater than those for the ant/ant subpopulations. The three ant genes showed significant associations with all malting quality traits tested. The Ant/Ant subpopulations were greater in extract, diastatic power and kernel plumpness, and lower in α-amylase activity and protein content than the ant/ant subpopulations in all three crosses. Both additive and dominance effects were observed for the association between ant 13 and biomass, plant height, spike number, grain yield and kernel weight, and for the association between ant 18 and plant height. Only additive effects were found for other significant associations with agronomic traits in all three crosses. Additive effects were significant for the associations between the three ant genes and all malting quality traits. Dominance effects were not estimated. The percentage of both phenotypic and genotypic variation explained by the ant gene associations was small. The percentage of the phenotypic variation varied from 1.23 to 5.97% in the F2 and F3 and from 2.26 to 12.82 in the F4 and F5 for the significant associations. The percentage of the genotypic variation ranged from 1.78 to 9.97% in the F2 and F3. The results from this study indicate that proanthocyanidin-free barley with acceptable agronomic and malting quality traits could be developed, although with considerable difficulty, due to pleiotropy and linkage of the ant genes to undesirable genes.