A double haploid (DH) population consisting of 111 lines was established by anther culture from a cross between Gui-630 (indica) and Taiwanjing (japonica). Based on the DH population, a linkage map comprising of 175 RFLP markers and covering a total length of 1,224.6 cM was constructed (Weng et al., 2001). QTLs were mapped by CIM (Composite Interval Mapping) and MCIM (Multiple-trait Composite Interval Mapping). They were re-evaluated with both univariate stepwise regression (for DTH trait alone) and multivariate stepwise regression (for VGTM and RGTM traits jointly) by using a significance level of 0.1 (Wu et al., 1999).

The QTLs on chr-11, were not significant in either of the stepwise regression analysis. They were therefore considered to be false positive and thus discarded. However, Gramene has included these QTLs in their curated maps with a word of caution.