Heterotic patterns in rapeseed (Brassica napus L.) using exotic germplasm

摘要

Chinese semi-winter rapeseed is highly different from spring and winter rapeseed. This study was conducted, 1) to evaluate the potential of semi-winter rapeseed for hybrid breeding in spring and winter rapeseed, and vice versa; 2) to asses the genetic effects involved and 3) to estimate the correlation of parental genetic distance (GD) with hybrid performance. Four spring male sterile lines ofNPZ-L embke(R) (MSL) from Germany and Canada, and four winter MSL lines from Germany were crossed with 13 Chinese rapeseed lines to develop F1-hybrids, which were evaluated together with their parents and commercial hybrids in two years. 8 spring growing environments in Europe and Canada for spring × semi-winter combinations, 4 winter growing environments in Germany for winter × semi-winter combinations and 3 semi-winter growing environments in China for all combinations were used for this evaluation. Although the exotic lines were not well adapted to the local environments, with poor seed yield per se, the combinations exhibited high heterosis and seed yield potential. In the spring growing environments, about 92% and 68% oombinations overcame the mean performance of their parents for seed yield and oil content, respectively; half of the combinations were superior to the local commercial hybrids for seed yield in the 2 winter growing environments in the first year; and the winter × semi-winter combinations exhibited higher heterosis than spring × semi-winter under semi-winter growing environments in China although the former flowered later and had a shorter period to develop seed than the latter. Additive genetic effects mainly contributed to hybrid performance as judged from high GCA/SCA ratios. A weak association between parental GD and heterosis was found, but the correlation between GCA(f+m) and hybrid performance was high.