Combining ability for resistance of Litopenaeus vannamei to ammonia nitrogen and dissolved oxygen

Three introduced populations of Litopenaeus vannamei were used to establish nine inbred and hybridized populations of F₁ by complete diallel cross, whose hypoxic tolerance and ammonia-N tolerance were compared. The performance for tolerance of each population was evaluated by analyzing combining ability and heterosis of hypoxic tolerance and ammonia-N tolerance. The results reveal that nine groups showed significant difference in tolerance to dissolved oxygen and ammonia nitrogen. Mid-parent heterosis of hybrids for resistance to high ammonia nitrogen and low dissolved oxygen traits were 14.09~42.57 and -52.48~31.39, respectively, while those of heterobeltiosis were 1.860~26.18 and -54.34~24.66, respectively. The general combining ability of parents and special combining ability of hybrid combinations influenced the tolerance performance of phybrid offspring, especially that UH group had higher general combining ability in tolerance traits of high ammonia nitrogen and low dissolved oxygen. The specific combining ability analysis reveals that UM×UH, which had stronger non-additive effect and hybrid superiority, was strong heterosis combination and could be used as candidate materials for further family selection.