A comparative study on growth,low-salinity and low-temperature resistance among the inbred and hybrid offsprings at larval stages for Litopenaeus vannamei

In order to improve the quality of Litopenaeus vannamei seedlings and explore the application of mass selection and crossbreeding methods in large-scale production of artificial breeding,a comparative study on inbred and hybrid offsprings within stock A was carried out.Stock A was introduced from America in 2008 and was then artificially selected for two generations.Stock B was selected from Guangdong cultured population in 2010.The inbred line AA(A♀?A♂)and reciprocal cross lines AB(A♀?B♂)and BA(B♀?A♂)between these two stocks were established.Then a comparative study on growth,low-salinity and low-temperature resistance at larval stages was conducted among these three lines.The results showed that the offsprings for AB showed the best resistance capacity of low-temperature and low-salinity among three lines.Under the low temperature of(13.0?0.9) ℃ and the low-salinity of 4.7 conditions,the survival rates for AB line was 27.5% and 64.6% higher than that of the inbred line AA,respectively.The growth rate for body weight at the grow-out stage were (253?55) mg/d for AB line,(208?52) mg/d for BA line and (219?36) mg/d for AA line.The growth rate for AB line was 21.6% and 15.5% faster than that of BA and AA lines.The results indicated that heterosis of Litopenaeus vannamei was closely related with mass selection for broodstock.