QTL Analysis for Expressivity of Hull-cracked Grain in Two-rowde Spring Barley

The exposure of the caryopsis through lemma and palea is called 'hull-cracked grain', which lowers the germinability and grade of malting barley. To breed new varieties with a low occurence of hull-cracked grains,quantitative trait loci(QTL) analysis was conducted using 146 doubled haploid lincs derived from Harrington ×　TR306.Interval mapping analysis revealed three significant QTLs on chromosomes 3H,5H and 7H. About 37% of the variation of the expressvity of hull-cracked grains was explained by these three QTLs in a spikelet-thinning condition where 1/4 of the spikelets were thinned at the flowering time. On the contraty the QTL on 5H was silent in normal or non-treated condition and 23% of the variation was determined by the QTLs on 3H and 7H. Some of the QTLs detected here had a pleiotropic effect on the grain size.