Predicting Heterosis and F1 Performance in Spring Rapeseed (brassica Napus L.): Genetic Distance Based on Molecular or Phenotypic Data?

In rapeseed, there is a constant need for increasing its genetic diversity, particularly through breeding of hybrid varieties in order to produce genotypes with improved seed yield, as well as other important agronomic traits. However, to create commercial hybrids, the knowledge of the genetic diversity of the parents is prerequisite, considering that the hybrid's performance greatly depends on the choice of parental lines. There is a lack of information about using the genetic distance to determine the extent of heterosis in spring rapeseed in Europe. The goals of this research were to determine the genetic variability of rapeseed breeding material for important agricultural traits, to analyse the differences in grouping of the parental genotypes based on their genetic distances determined by morphological traits and molecular markers and to estimate the correlation of the differently established parental genetic distances with hybrid performance, heterosis, general combining ability of both parents and specific combining ability in crosses. This will provide novel information for parental selection in order to develop a better approach for prediction of heterosis in spring rapeseed hybrid breeding program. The field trial included ten spring rapeseed genotypes that were crossed in a half diallel fashion thus making 45 hybrid combinations. Distances between parents were calculated based on data from 14 analysed phenotypic traits and 64 SSR markers. The obtained results showed that the parental genetic distance based on phenotypic traits was better in predicting heterosis and combining ability in comparison with the distance estimated by SSR analysis. Although the obtained results revealed that the genetic distance based on molecular markers had no correlation with mid-parent and high-parent heterosis, further studies are needed with a larger number and different types of markers to draw the final conclusion.