Genotype by environment interactions for productive traits of purebred and crossbred abalone strains under different rearing modes.

China is the world's largest abalone farming country, with production reaching 203,000 tons in 2020. In the last few decades, interspecific hybridization has been carried out in China and achieved a certain level of success, and rearing techniques have been rapidly developed. To systematically evaluate the performance of purebred and crossbred strains under different culture modes, we determined the magnitudes of the Genotype by Environment Interactions (GEI) to identify stable and high growth performance strains. Two purebred (Haliotis discus hannai and H. gigantea) and four crossbred abalone strains were evaluated in three representative culture modes (Inland industrial aquaculture mode, Sea-based aquaculture mode and South-North (S-N) relay mode). After 2 years of culture, the growth performance of strains varied with different culture modes. Both H. discus hannai ♀ × H. fulgens ♂ (DF) and H. gigantea ♀ × H. discus hannai ♂ (SD) exhibited significant heterosis in all three culture modes, and H. discus hannai ♀ × (H. discus hannai ♀ × H. fulgens ♂) ♂ (DD × DF) and (H.gigantea ♀ × H. discus hannai ♂) ♀ × H. discus hannai ♂ (SD × DD) showed significant growth advantages compared to the purebred parents of H. discus hannai (DD) and H. gigantea (SS). A combined analysis of variance revealed significant genotype by environment interactions for shell length (14.2%), harvest weight (8.7%), and fullness index (10.4%), indicating that phenotype reranking occurred under different culture modes. The average performance for shell length, harvest weight, and the fullness index followed the pattern: DF > DD × DF > SD > SD × DD > DD > SS. Combining the results of growth assessment and genotype by environment interaction analysis, the following conclusions can be drawn: 1) DF was the highest yielding genotype among the three culture modes and should be promoted. 2) SD and D × DF had notable performance under the S-N relay mode, suggesting that these could be used as suitable strains for S-N relay rearing. 3) In the case of purebred SS, the sea-based aquaculture mode was the best option. 4) The S-N relay mode significantly improved the economically important traits of most of the strains. The results from this study can provide critical advice for different strains as well as guidance for the abalone farming industry in world. • A comprehensive field study on the purebred and hybrid abalone strains cultivated in three culture modes was reported. • The hybrid H. discus hannai ♀ × H.fulgens ♂ exhibited the most growth under South-North relay mode. • South-North relay mode can significantly improve the economical traits of most of the strains. [ABSTRACT FROM AUTHOR]