Quantitative trait loci affecting germination traits and malt friability in a two-rowed by six rowed barley cross

When barley endosperm is properly modified during malting, the resulting malt is soft and friable. Factors that interfere with endosperm modification, such as. poor germination, large kernels and high protein, are expected to reduce malt friability. We measured two germination traits and malt friability in 140 lines derived from the Harrington/Morex barley cross. As expected, malt friability was positively correlated with germination, malt extract and soluble/total protein and negatively correlated with kernel size, grain protein, extract (1 --> 3,1 --> 4)-beta-glucan and extract viscosity. Quantitative trait loci (QTLs) were mapped for the germination traits and for malt friability. The proportion of the observed variation explained by these QTLs was low (less than one-third) for germination, but was high (two-thirds) for malt friability. For malt friability, seven QTLs were detected by composite interval mapping. QTLs on chromosomes 2 (2H), 4 (4H) and 7 (5H) coincided with QTLs for germination and/or with QTLs that have been reported for grain and malt traits in Harrington/Morex. Others (on chromosomes 1 (7H), 3 (3H) and 6 (6H)) may be more specific to malt friability. Both parents contributed favourable QTL alleles. It should be possible to select for improved malt friability using marker-assisted selection and/or selection based on phenotypic values for malt friability and related traits. (C) 2004 Elsevier Ltd. All rights reserved.