Ploidy level, morphological characteristics and performance of interploid hybrids by Megalobrama amblycephala♀× allo-tetraploids ♂

Abstract

Interploid hybrids were produced by mating allo-tetraploid males, an interspecific tetraploidy induced by blunt snout bream (Megalobrama amblycephala) ♀× black bream (Megalobrama terminalis) ♂, with blunt snout bream females. The fertilization rate was high in the interploid hybrids. Although significant (P<0.05) mortalities were observed at hatching, swim-up and 30-day stages, respectively, the survival percentage of the interploid hybrids became stabilized after the 60-day stage. In different interploid hybridization batches, 64–97% of juveniles were identified as 3n and 1–36% as 2n. Less than 2% of tetraploids were obtained in these interploid hybridization batches. The daily growth rate of the interploid 3n increased 7.5%, compared with that of diploid blunt snout breams during the 180-day culture. Moreover, a method using seven morphological parameter ratios was set up with a relatively high classification accuracy of 93.8% to harmlessly discriminate interploid 3n from allo-tetraploids, black bream and blunt snout bream.