Fig. 3. The QTL mapping of six traits in barley (data of the 1997 field experiment reported by Yin et al., 1999b). The interval mapping method (Lander and Botstein, 1989) was used. By moving the position of the putative QTL along the genetic map (horizontal axis), a profile of the test statistics, QTL likelihood (LOD), was produced for each chromosome, and results are given here for chromosome 3. The peak of the LOD profile indicates the most likely position of a QTL affecting the trait under study. Results indicate a major QTL at 126.4 cM on chromosome 3 (note that this is also the position of the denso gene as shown in Fig. 2). A in each figure refers to the additive effect of this QTL on the trait, defined as (mean of dwarf genotypes - mean of nondwarf genotypes)/2. DS, developmental stage.