Estimation of Genetic Parameters for Yield, Yield Components and Glucosinolate in Rapeseed (Brassica napus L.)

Eight genotypes of rapeseed (Brassica napus L.), including six cultivars and two breed-ing lines, were used to determine the genetic parameters for number of pods per main axis (NPM), number of pods per plant (NPP), length of pod (LOP), number of seeds per pods (NSP), ۱۰۰۰-seed weight , seed yield, and total glucosinolate. Analysis of variance based on Hayman’s method revealed significant general (a) and specific (b) combining ability mean squares for all traits except for ۱۰۰۰-seed weight, which indicated the impor-tance of additive and non-additive genetic effects. For ۱۰۰۰-seed weight, only the general combining ability mean square was statistically significant. Significant ratios of a to b mean squares and high narrow-sense heritability estimates were observed for ۱۰۰۰-seed weight and total glucosinolate, which indicated the importance of additive genetic effects for these traits. Therefore, the efficiency of selection for improving these traits will be high. The significant b۱ (mean deviation of F۱’s from their mid-parental values) mean squares for all of the studied traits except LOP and ۱۰۰۰-seed weight, exhibited direc-tional dominance and subsequently significant average heterosis. Significant maternal (c) mean squares were observed for all of traits, except LOP. Among yield components, NPM and NPP had a significant correlation with seed yield and can therefore be used as good criteria for improving seed yield. The correlation between seed yield and total glucosi-nolate was not significant, and so reducing this antiquality trait without any considerable changes in seed yield is possible. In general, the parents PF۷۰۴۵/۹۱ and BL۱ were good combiners and the crosses BL۱×PF۷۰۴۵/۹۱, BL۱×BL۲ and PF۷۰۴۵/۹۱×Shiralee were good combinations for improving seed yield and total glucosinolate, simultaneously.