Abstract:

To find out elite restorer lines during high yield hybrid breeding, 3 Polima cytoplasmic male sterile （Pol CMS） lines of spring Brassica napus L. were used to formulate stronger hybrid combination in spring rapeseed area. SLAF-seq was used to develop SNP markers for the 3 sterile lines and also 118 restorer lines. All 121 materials were clustered based on SNP markers. According to clustering results and their flowering times, 40 restorer lines were selected from each categories to the 3 sterile lines respectively. Under the adopted NCⅡ design, 120 hybrid combinations were prepareed and analysed on their combining ability, heterosis and correlation of parental genetic distance, combined cluster and high-yield combinations. Results showed that genetic clustering divided 121 B. napus resources into 5 categories. The 3 sterile lines were grouped into category V. General combining ability （GCA） of the 43 parents varied from -20.78 to 30.42. Three restorer lines （R83, R107 and R13） and one sterile line S3 （105A） had larger GCA. In the combinations, S3×R13, S1×R48, S3×R11, and S2×R89 had higher special combining abilities. The combination S3×R13 had the largest yield over-standard heterosis and over-parent heterosis （37.12% and 42.52% respectively）. Genetic distance and individual yield were extremely positively correlated, with correlation coefficient of 0.390. Among the hybrid combinations, most of the restorers with top 20 yields were from Type I group, which had large genetic distance with the sterile lines. Meanwhile, some varieties popularized in spring rape areas, including restorer lines of Qingza 2, Qingza 7, Qingza 9 and Qingza 12 were all derived from hybrids of Type I and sterile line S3 （105A）. Therefore, it was considered that sterile lines crossed Type Ⅰ restoring lines could be strong hybrid combination in spring B. napus.

Key words: Brassica napus L., Polima CMS （cytoplasmic male sterile）, restore lines, combining ability, heterosis, heterosis model