Abstract:

【Objective】 Cross combinations from six rapeseed cultivars and lines were investigated under waterlogging stress in order to understand the genetic mechanism of waterlogging tolerance of Brassica napus L. and to provide reasonable improvement programs. 【Method】 Six germination traits were investigated under waterlogging stress on the combining ability and heritability using complete diallel crossing method designed for 30 combinations from six cultivars and lines. The traits include relative root length, relative stem length, relative fresh weight per plant, relative survival rate, electrical conductivity and relative vigor index. After flooding treatment, the six traits of parents and F1 were measured and the general combining ability (GCA) and special combining ability (SCA) of germination traits were analyzed using GriffingⅠmethod. 【Result】 Among 30 cross combinations, the GCA was significantly different among the 6 waterlogging resistance traits. The SCA of these traits was significantly different except the SCA of electrical conductivity. As the representative trait of rapeseed tolerance to waterlogging, relative vigor index had the highest narrow heritability and relatively low broad heritability. Cultivar Zhongshuang 9 and P79 had high tolerance potential to waterlogging. 【Conclusion】 The combining ability and genetic effects analysis of relative vigor index during germination stage can be used to identify the waterlogging tolerance of rapeseed and improve the breeding program.

Key words: Brassica napus L., relative vigor index, waterlogging tolerance, germination trait, combining ability, diallel crossing