This paper aims to probe into relationships between genetic diversity of inbred lines, estimated through the Mahalanobis distance and the effects of specific combining ability (SCA) and heterosis. The SCA and heterosis effects were analyzed for nine quantitative traits of eight inbred lines and their diallel cross hybrids of spring rape. The field experiments (with F1 and F2 generations) were carried out in a partly balanced square design with four replications. The results show that the Mahalanobis distances for inbred lines and SCA effects of the hybrids were mostly positively correlated. However, the Mahalanobis distances were usually not related, or very weakly, with the heterosis effects. On this basis we conclude that it is possible that the genetic diversity of crossed lines does not have to affect heterosis effects in the hybrids derived from the crossing. Since, as far as could be determined, this is the first conclusion of this type in literature, it calls for further research to study this phenomenon.

genetic distance; heterosis; Mahalanobis distance; phenotypic correlations; SCA; spring rape

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia