Phenotypic effects of introgressing French winter germplasm into hybrid spring canola

Introgression of winter germplasm into spring oilseed Brassica napus L. represents a novel approach to broaden its genetic base and potentially boost seed yields of hybrid cultivars. To determine the potential usefulness of this approach, two large populations of segregating doubled haploid (DH) lines were developed by crossing germplasm derived from two French winter cultivars with a male parent of a hybrid combination. These lines were evaluated per se (2 yr in Wisconsin, USA) and in testcrosses with a spring canola line used in commercial canola hybrids (2 yr each in Wisconsin, USA, and Saskatchewan, Canada). Thirty percent of the hybrids significantly (P < 0.05) out-yielded the mean of commercial hybrids included in each trial. In addition, many hybrids significantly out-yielded the starting hybrid combination, especially in the Canadian environments. Earlier flowering DH lines and hybrids tended to have higher yields, as indicated by the highly significant (P < 0.01) negative correlations between seed yield and days to flowering in most trials. The results of this study illustrate that introgression of these winter germplasms can improve seed yield in spring canola hybrids. These populations will be useful for identifying genes that affect seed yield of canola hybrids.