Diallel crosses of eight cultivars and breeding lines of safflower were conducted and F1 and F2 generations were evaluated to estimate genetic parameters for morphophenological traits, seed yield, yield components and quality traits including oil and protein contents and different fatty acids (linoleic acid, oleic acid, palmitic acid and stearic acid) using Griffing’s methods 1 and 2 for F1 and F2 generations. Jinks and Heyman method was also used to estimate genetic parameters in two generations. Sixty four genotypes including 8 parents and 56 F1 progenies, and half diallel crosses of F2 generation were evaluated in a lattice and randomized complete block designs, for F1 and F2 generations, respectively. Analysis of variance based on Griffing’s method revealed significant general combining ability (GCA) and specific combining ability (SCA) mean squares for all studied traits in F1 and F2 generations, except for budding stage in two generation, and implementing the importance of additive and non-additive genetic effects. Significant ratio of GCA to SCA mean squares, high narrow-sense heritability estimates and low degrees of dominance for plant height, seeds per head, linoleic acid and oleic acid in two generation, indicated the prime importance of additive genetic effects for these traits, Hence, breeding procedures based on selection would obtain high efficiency for these traits. Low narrow-sense heritability estimates and high degrees of dominance for days to flowering, heads per plant, oil and protein percent, indicated the importance of non-additive genetic efficiency for these traits. Hence the efficiency of hybrid production method would be high for them. Therefore, hybrid-based breeding methods would obtain high efficiency for these traits. Significant reciprocal and maternal (c) mean squares were estimated by Griffing’s and Heyman method, respectively, indicated the importance of cytoplasmic genetic factors for controlling these traits. Leaf antioxidant activity including gluthation reductase (GR), super oxid dismutaze (SOD), ascorbate peroxidase (APX), carotenoids, lipid peroxidation (LP) and chlorophyll content (a, b, a+b) were evaluated in 20 genotypes derived from crosses of four parental genotypes. Analysis of variances for genotypes showed the significant Keywords Heritability, Additive genetic effect, Combining ability, Dominance.
