Increasing seed oil content is an important breeding goal for Brassica napus L. (B. napus). The identification of quantitative trait loci (QTL) for seed oil content and related traits is important for efficient selection of B. napus cultivars with high seed oil content. To get better knowledge on these traits, a molecular marker linkage map for B. napus was constructed with a recombinant inbred lines (RIL) population. The length of the map was 1,589 cM with 451 markers distributed over 25 linkage groups. QTL for seed oil content, seed hull content and seed coat color in three environments were detected by composite interval mapping (CIM) tests. Eleven QTL accounted for 5.19-13.57% of the variation for seed oil content. Twelve QTL associated with seed hull content were identified with contribution ranging from 5.80 to 22.71% and four QTL for seed coat color accounted for 5.23-15.99% of the variation. It is very interesting to found that co-localization between QTL for the three traits were found on N8. These results indicated the possibility to combine favorable alleles at different QTL to increase seed oil content, as well as to combine information about the relationship between seed oil content and other traits.

In this study, the correlations among these characters were investigated in 18 rapeseed (Brassica napus L.) accessions with different seed coat color. The results indicated that seed water uptake and flooding tolerance were significantly correlated with seed color and melanin pigment content of testa. The red or black-seeded accessions had higher melanin content in testa, showed slower water uptake and lower leakage and higher flooding tolerance. The majority of yellow-seeded rapeseed accessions which had low melanin pigments content in testa showed a rapid water uptake and higher leakage than the red or black-seeded, which led to imbibition damage and lower flooding tolerance. The results suggest that the yellow-seeded cultivars experienced poor field emergence and more serious pre-harvest sprouting in raining weather than the dark-seeded cultivars. Some yellow-seeded accessions showed a slow imbibition behavior and relative high flooding tolerance, indicated these accessions can be used as a genetic resource to improve the flooding tolerance and reduce imbibition damage for the yellow-seeded B. napus L.