Analysis of combining ability, heterosis and genetic correlation on growth traits of GIFT tilapia

Gift strains of Nile tilapia ( Oreochromis niloticus) have become the main aquaculture fish in Chinas tilapia industry. We constructed nine complete set combinations through 33 complete diallel cross among three strains of Gift Nile tilapia ( New GIFT, GIFT and Genomar) to analyze the combining ability, heterosis and genetic correlation in F1 progenies among these nine combinations for five growth traits ( body weight, total length, body length, body height and body width) . No general combining ability was detected for the five growth traits, while the special combining ability was over 62%, which indicates that the growth traits were mainly affected by special combining ability. Significant heterosis was observed in the three combinations of Genomar♀ New GIFT♂, New GIFT♀ Genomar♂ and GIFT♀ New GIFT♂, among which Genomar♀ New GIFT♂ was the best complete set combination. Besides, significant genetic and phenotypic correlations were detected among the five growth traits ( P0.05) , indicating polymerization utilization could be conducted in multiple traits in the future. Thus, the results provide references for complete set utilization and breeding of GIFT tilapia.