Heterosis and breeding of high oil content in rapeseed ( Brassica napus L . )

High oil content is one of the most important characteristics for rapeseed (Brassica napus L.) breeding. In this study, eleven canola Brassica napus lines (varieties) with different oil content (32.48%-52.61%) and genetic background, were chosen to make sixty-two reciprocal crosses in order to test the heterosis of oil content in Brassica napus L. and identify the breeding potential for high oil content hybrids. Results showed that out of 62 crosses, 30 crosses exhibited positive mid-parent heterosis and 7 exhibited positive over-parent heterosis for seed oil content, which accounted for 48.39% and 11.29%, respectively. The positive mid-parent heterosis percentage and over-parent heterosis percentage ranged from 0.43% to 9.86% and 0.46% to 8.67%, respectively. The results suggested that: 1) obviously positive mid-parent and over-parent heterosis exhibited in the combination between two low oil content parents, but the oil content of their F1 hybrid was still low; 2) small positive mid-parent and over-parent heterosis could be gotten in some combinations if the oil contents of their parents were at the same level, whether at a medium or high level; 3)obviously negative mid-parent and over-parent heterosis existed in hybrid combinations between low and high oil content parents; 4) it is essential that both two parents should be high oil content if we would like to get a high oil content hybrid. A registered canola cultivar Zhongshuang 11 with oil content of 49.04% and a canola hybrid with oil content of 49.84% was developed in our breeding group very recently.