| Fenneropenaeus chinensis is one of the China's most representative indigenous aquaculture species.Its tolerance range of water temperature is 4~38?.In the 60 s to 90 s of the 20 th century,shrimp farming industry in our country occupies the important status of seawater aquaculture industry.Due to many factors,such as overfishing,habitat ecological environment destruction and so on,the production of shrimp farming were dropped sharply,especially since the outbreak of white spot syndrome virus(WSSV)in 1993.The farming of F.chinensis has been recovered to some extent through improvement in the breeding mode,breeding technology and selecting breeding.But in recent years,the intensified abnormal climate especially repeated cold disaster nationwide has resulted in mortality of a large number of shrimps in the culture,and has become another major problem in shrimp breeding.Therefore,the breeding of cold tolerance varieties is expected to solve the problems as above.In this study,a preliminary evaluation of cold tolerance and growth traits for the generation of G10(99 families)and G11(189 families)generations of F.chinensis juveniles and G10 generation(69 families)of F.chinensis adults was conducted by means of indoor artificial cold tolerance challenge.A linear mixed model was established with average information restricted maximum likelihood.The genetic parameters and genetic gains for growth and cold tolerance traits in F.chinensis were evaluated by ASReml software.It was expected to provide a certain theoretical basis for breeding of cold tolerance variety of F.chinensis.The main results are summarized as follows:1.Evaluation of Genetic Parameters for growth and cold tolerance traits in F.chinensis JuvenilesThe heritabilities of G10 generation for body weight(BW)and body length(BL)were 0.078 ± 0.124,0.131 ± 0.133,respectively;and the heritabilities of G11 generation for BW and BL were 0.073 ± 0.101,0.072 ± 0.101,respectively.They were all low heritability and not significantly different from zero(P > 0.05).Across generations,the heritabilities of BW and BL were 0.196 ± 0.091 and 0.095 ± 0.078,were more stable compared with within-generations.The common environmental effect estimates were high(ranged from 0.341 ± 0.066 to 0.373 ± 0.055)and both are significantly different from zero(P < 0.05).The results indicated that the heritability and common environmental effects show the opposite trend.In this study,cooling degree hours(CDH)and temperature at death(TAD)are measure parameters for cold tolerance of F.chinensis.The heritabilities of cold tolerance traits were medium or low.The heritabilities of CDH and TAD for G10 generation were 0.077 ± 0.058,0.265 ± 0.091,respectively;and the G11 generation were 0.135 ± 0.080,0.132 ± 0.052,respectively.The heritabilities of two generation between CDH and TAD estimates were 0.050 ± 0.039 and 0.085 ± 0.034,respectively.The heritability of TAD were significantly different from zero(P < 0.05),and the heritability of CDH heritability were not significantly different from zero(P > 0.05).It also shows that the heritability and common environmental effects show the opposite trends,indicated that there is a certain degree of confusion between the additive genetic variance and the common environmental variance.2.Correlation analysis of growth traits and cold tolerance traits in F.chinensis juvenilesThe phenotypic and genetic correlations were highly positive correlation between BW and BL,the phenotypic correlation coefficients ranged from 0.9324 ± 0.0027 to 0.9408 ± 0.0040,the genetic correlations ranged from 0.7701 ± 0.7216 to 0.9991 ± 0.0567.While the phenotypic and genetic correlations between CDH and TAD were medium or high negative correlation.The phenotypic correlation ranged from-0.5470 ± 0.0174 to-0.8244 ± 0.0069,and genetic correlations of across-generation was significantly lower than the genetic correlation of within-generation.The absolute values of genetic correlation coefficients between BW,and TAD and CDH Were medium or low,ranged from 0.0602 ± 0.4632 to 0.5923 ± 0.7218,and the absolute values of phenotypic correlation coefficients ranged from 0.0760 ± 0.0317 to 0.0953 ± 0.0285,were low.The genetic correlation between BL,and CDH and TAD were not stable in within-generations,the absolute values ranged from 0.0526 ± 0.4664 to 0.9914 ± 0.7010,whereas the phenotypic correlation coefficients between BL,TAD and CDH are comparatively low.The results showed that the phenotypic correlations between growth and cold tolerance traits of F.chinensis were weaker,but the genetic correlations were stronger.The genetic correlation between various traits from within-and across-generations have a significantly different,therefore,further studies are required for the correlation of different traits of F.chinensis,so as to provide more accurate data for breeding of cold tolerance F.chinensis.3.The predicted responses of growth and cold tolerance traits after one generation selection in F.chinensis juvenilesThe predicted responses estimated for BW and BL using two set of genetic parameters obtained from within-and across-generations datasets were low,namely-0.009,-0.140,-0.128,0.033.The predicted responses estimated of TAD were 0.221,0.004,respectively;and the predicted responses estimated of CDH were 2.112,1.112,respectively.The predicted responses estimated for cold tolerance traits were low,which indicated that the cold tolerance traits of F.chinensis could not obtain satisfactory breeding effect after multi generation breeding.4.Evaluation of genetic parameters for growth under low-temperature and cold tolerance traits in F.chinensis adultsA preliminary evaluation was conducted on cold tolerance and growth traits of 69 F.chinensis families by means of indoor artificial cooling in this study.The heritabilities of body weight(BW)and body length(BL)under Low-temperature in F.chinensis were medium or low(0.206 ± 0.177 and 0.187 ± 0.179,respectively).The heritability of the survival status at half lethal time(SS50)for cold tolerance traits was 0.020 ± 0.253.The phenotypic and genetic correlation coefficients between BW and BL under Low-temperature were 0.8233 ± 0.0102 and 0.969 ± 0.018,respectively,which were relatively high.The phenotypic correlation coefficients between BW,BL,and SS50 were comparatively low,namely 0.2082 ± 0.0353 and 0.2384 ± 0.0343,respectively.The genetic correlation coefficient between BW,BL,and SS50,were comparatively higher,namely 0.5212 ± 0.2052,0.5422 ± 0.2031.Compared with juvenile shrimp,the genetic correlation of adults shrimp between growth traits and cold tolerance traits were higher,showing that the selection of cold tolerance variety in F.chinensis could be conducted together with the breeding of growth traits. |
PDF Full Text Request