The waxy (wx) gene, locating on barley chromosome 1, encodes starch synthase, which produce amylose, and determines nonglutinous or glutinous quality of starch in the barley endosperm. The waxy mutation contributes to high soluble fibre, -glucan. High soluble fiber diets have been shown to reduce blood cholesterol content. High fiber varieties show poor yield performance.

With the objective of discovering the genetic basis for poor performance in waxy hull-less barley, we made a cross between MTaz90-123 (waxy hull-less and high fiber content) and MTH3860224 (high yielding feed barley line). We generated a linkage map, and identified QTLs associated with -glucan content and grain yield to elucidate the relationship between two traits. Four QTLs for grain yield and six QTLs for -glucan content were detected, accounting for about 44% and 70% of the phenotypic variance respectively. Multiple regression analysis was conducted to determine the contributions of each locus for grain yield and -glucan content. Whereas locus N showed second-greatest contributing factor for grain yield, the waxy gene contributed positively to -glucan content without any measurable impact on grain yield.