Gene action and heterosis studies for yield and yield contributing traits in Rapeseed (Brassica napus L.) genotypes by line x tester analysis

The study was conducted to evaluate five female parents (lines) and eight male parents (testers) in a line x tester mating design at the research field of Sher-e-Bangla Agricultural University, Bangladesh, to estimate their gene action and heterosis for seed yield and yield contributing attributes in rapeseed. The data recorded on 40 F1’s and their parents for their combining ability indicated that the GCA effect was significant for primary branches per plant, secondary branches per plant, number of siliqua per plant, seeds per siliqua, thousand seed weight and seed yield per plant. High ratio of GCA and SCA variance was observed indicating a preponderance of non-additive gene effects in the inheritance of the yield and yield contributing characters under study. Among the lines Nap 9908 and Nap 94006 were found as good general combiners. Among 40 hybrids 16 were found as a good specific combiner for yield and yield contributing characters. Different types of heterosis, i.e. heterosis over mid parent (Hm), heterosis over better parent (Hb) and heterosis over the standard check (Hc) were estimated to evaluate forty hybrids for seed yield and yield contributing characters. The average heterosis for seed yield of forty hybrids over mid parent was 3.27% and that of better parent and the standard check was -9.72% and 5.60%, respectively.