Decoding Gene Activity and Heterosis: Line × Tester Analysis for Yield Traits in Rapeseed (Brassica napus L.)

The study aimed to assess five female lines and eight male testers using a line × tester mating design at Sher-e-Bangla Agricultural University in Bangladesh over two consecutive years during the winter season (from November to April). The objective of this study is to investigate the genetic basis of heterosis and gene activity for yield and related traits in rapeseed (Brassica napus L.) genotypes using line × tester analysis, with the aim of identifying superior parental lines and hybrids for enhanced productivity and breeding efficiency.

Data collected from 40 F1 hybrids and their parental lines revealed significant general combining ability (GCA) effects for traits such plant height, days to 50% flowering, number of silique/plant, seeds/siliqua, thousand seed weight and seed yield/plant.

A high ratio of GCA to specific combining ability (SCA) variance suggested that non-additive gene effects play a significant role in the inheritance of these yield traits. Lines Nap 9908 and Nap 94006 were identified as strong general combiners, while 16 of the hybrids were recognized as good specific combiners for yield and associated traits. Various types of heterosis- over mid parent (Hm), better parent (Hb) and a standard check (Hc)- were measured for the forty hybrids. The average heterosis for seed yield over the mid parent was 3.27%, while it was -9.72% over the better parent and 5.60% over the standard check. Lines Nap 9908 and Nap 94006, along with 16 high-performing hybrids, are acclaimed for enhancing rapeseed productivity, emphasizing hybrid breeding to exploit non-additive gene effects and heterosis.