Inheritance pattern and gene action of biochemical attributes in rapeseed (Brassica napus L.)

The knowledge of gene action and inheritance pattern is of prime importance for a breeder to choose the correct breeding strategy for crop improvement. To understand the inheritance pattern of the quality trait in rapeseed, an experiment of 8 x 8 complete diallel crosses was conducted. The scaling test analysis proved the full adequacy of Hayman's additive- dominance model for all traits except oleic acid and erucic acid contents. The analysis showed the role of both additive and dominance gene action in the manifestation of studied traits. The larger values of dominance (H1, H2) than additive genetic components of variation (D) indicated the prime importance of the non -additive genetic effect. The E component was also significant specifying unstable expression of these traits due to the environmental influence. The Vr/Wr graph and the average degree of dominance revealed over dominance type of gene action for the studied traits. The scattering of genotypes on the regression line proved sufficient genetic diversity for studied traits among parental genotypes. The distribution of array points revealed that genotypes AUP-05 possessed the most dominant genes whereas genotypes AUP-06 possessed the most recessive genes for most of the studied traits. Heritability analysis also revealed the greater role of dominant genes and environment effect in controlling these traits. From these results, it could be suggested that selection could be effective in later segregating generations for improving these quality parameters.