Study on combining ability and heterobeltiosis of agronomic traits in spring type of rapeseed varieties using line × tester analysis

Abstract

To estimate the general and specific combining ability (GCA and SCA) and high parent heterosis
(heterobeltiosis) effects of phenological traits, plant height and seed yield, two testers and six lines of spring
type of rapeseed varieties were crossed using line×tester fashion. Significant mean squares of parents and
crosses for all the traits indicated significant genetic variation among the parents and their F1 crosses.
Significant mean squares of parent’s vs crosses revealed significant average heterosis for all the traits. High
narrow sense heritability estimates for all the traits except days to flowering, indicating the importance of
additive genetic effects for these traits except days to flowering. Due to more importance of additive genetic
effects for most of the traits, significant specific combining ability and heterobeltiosis effects of the studied
traits were observed for only a few of the crosses except days to flowering. Significant SCA effects of the
traits were observed for the crosses which had at least one parent with significant GCA effects. Significant
correlation between heterobeltiosis effects of seed yield and their respective mean performances of the
crosses, indicating selection of the crosses based on heterobeltiosis can be indirect selection for high seed
yield of the cross combinations.