| Three lines, each carrying a different proanthocyanidin-free 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 $alpha$-amylase activity and protein content than the ant/ant subpopulations in all three crosses.;Both additive and dominance effects were observed for the associations 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.;It was concluded that pleiotropy was the primary cause for the associations between the three ant genes and biomass and plant height, and for those between ant 17 and 18 and grain yield. Association between ant 13 and grain yield and those between the three ant genes and kernel weight were probably due to pleiotropy and linkage. Linkage was more likely than pleiotropy as the cause for the associations between ant 13 and spike number, days to heading and harvest index, and between ant 18 and fertility.;Both linkage and pleiotropy were probably involved in the associations between ant 13 and 18 and $alpha$-amylase activity, and between ant 18 and kernel plumpness. Pleiotropy alone was probably the major cause for the association between ant 17 and $alpha$-amylase activity, and for the associations between ant 13 and 17 and kernel plumpness. Associations between the three ant genes and malt extract, protein content and diastatic power were more likely due to pleiotropy than to linkage.;The percentage of both phenotypic and genotypic variation explained by the ant gene associations was small. It varied from 1.18 to 8.05 in the F$sb2$ and F$sb3$ and from 3.58 to 16.84% in the F$sb4$ and F$sb5$ for the significant associations.;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. |
