Study On The Compound Breeding Of The Shell Color And Growth Traits Of Hyriopsis Cumingii "shenzi No.1"

Hyriopsis cumingii is a kind of specific freshwater pearl shellfish in China.As is known to all,the color of pearl affects its value.Studies have shown that the color of pearl is related to the shell color of the donor mussels and the size is associated with the growth traits of the host mussels.In this paper,the shell color of Hyriopsis cumingii was studied,and the correlation between the inner and outer shell color of the different times was discussed in the shell transparent stage,and the optimum breeding time with shell color as selection index was also got.Taking shell length and dark purple shell as target traits,and based on the new strain of purple Hyriopsis cumingii,"Shenzi No.1",which evaluated separately the best selection strategy of the early stage and pre-implantation stages for hybrid breeding of growth traits and shell color traits of the first generation.Using paternity test technique to identify the progeny of Hyriopsis cumingii,the paper also estimated its genetic parameters of growth traits and shell color,and the interaction between genotype and environment.The main contents of the study were as follows:1.Correlation analysis of inner and outer shell color of Hyriopsis cumingii at different months of age during shell transparent stageIn the early stages of development there is a shell transparent phase.At this stage,the inner shell color can be observed through the shell.In order to study the influence of the color parameters of the outer shell on that of the inner shell of Hyriopsis cumingii,30 purple juveniles were randomly selected as purple contemporaneous group at the age of 4months,4.5 months,5 months,5.5 months,6 months and 8 months old.The color parameters both the inner and outer shell of purple contemporaneous group were measured at the same time.The purpose is to analyze the correlation of shell color during the same period.In addition,purple and white lines of purple strain group and white strain group were used as experimental materials.Besides,each of them were continuously observed.The outer shell color parameters of little Hyriopsis cumingii on each measuring period were measured respectively.The inner shell color parameters of 8 months old were also measured.The purpose is to analyze the correlation of shell color during the different period.Therefore,the result of correlation analysis between the comprehensive contract period and the early stage was that the 5 months old was the best breeding period.2.The influence of breeding effect on the selection order and retention rate of the growth and inner shell color traits of 5 months old Hyriopsis cumingii during shell transparent stageAt the early stage,the shell of the strain F₁ of“Shenzi No.1”was transparent.In this study,seven different selection methods were set according to the different selection order and retention rate of the objective traits.When shell length（SL）was the first selected trait and deep purple shell（PN）was the secondary selected trait,the methods are SL50%×PN20%,SL30%×PN33%and SL20%×PN50%respectively.However,when the selection order is opposite,the selection methods were PN50%×SL20%,PN30%×SL33%and PN20%×SL50%.Moreover,according to conventional experience,the juveniles of deep purple shell and large size were selected simultaneously.The aim was to compare the experimental results of the control group with that of the other six methods.The total retention rate of each method was 10%.After five months’culture,the growth traits（shell length,shell height,shell width,body weight,mantle weight and shell weight）and the inner shell color parameters（L^*,a^*,b^*,dE^*）of the selected mussels were measured to evaluate the early selection effects of these seven methods.The results showed as followed.1)The different selection methods lead to the difference in the early selection effect.The growth traits of individuals selected by PN50%×SL20%and PN20%×SL50%were the best.However,when the deep purple shell was selected as the objective trait,the other three methods were better than the above methods.They were SL50%×PN20%,SL30%×PN 33%and SL20%×PN50%.The traits of Hyriopsis cumingii selected by the traditional method were not prominent in all the experimental groups.2)The results showed that the selection order had a significant impact on the selection effect.In addition,the traits with high expectations were selected at the end and the effect of selection was better.3)Both the retention rate and the compound selection response affected the selection effect.3.The influence of breeding effect on the selection order and retention rate of the growth and inner shell color traits of Hyriopsis cumingii before grafting the mantle piecesIn this paper,10 months old individuals from the breeding group selected by the chapter 2 breeding methods PN50%×SL20%were used as experimental materials.The six kinds of selection methods were set up,including SL20%×PN50%（1）,SL30%×PN33%（2）,SL50%×PN20%（3）,SL70%×PN14%（4）,SL80%×PN13%（5）and control group（6）.Through this,the best selection strategy for compound breeding of shell color and growth traits of Hyriopsis cumingii was studied before grafting the mantle pieces.The results showed that the first method,SL20%×PN50%,was the best choice in terms of shell length,shell width,body weight,shell weight,L^*and dE^*,which indicated that the first method was the best for the compound breeding of shell color and growth traits of Hyriopsis Cumingii before grafting the mantle pieces.4.Estimation of genetic parameters of growth traits and inner shell color,and analysis of interaction between genotype and environment of the strain F₁ of“Shenzi No.1”of Hyriopsis cumingiiIn this paper,two groups of multiples PCR panels were constructed by using 6 pairs of microsatellite primers.Based on the analysis of paternity test and genetic structure of 8 matriarchal families of the first genation of“Shenzi No.1”.The number of effective individuals was1,511 and 26 full-sibs families were identified.The above results indicate that the genetic diversity of Hyriopsis cumingii is high.Heritability estimates of shell length,shell height,shell width,and body weight was high,while that of shell weight was moderate.There was a positive correlation between these five growth traits.Heritability estimates of L^*,a^*and dE^*was moderate,while that of b^*was low.L^*is negatively correlated with dE^*in the color parameters.L^*is negatively correlated with shell length and shell height,and dE^*is positively correlated with shell length and shell height.When the sediment of the cage was the same,the growth and shell color characteristics of Hyriopsis cumingii in different depths are different.When the depth of the cage was the same,the Hyriopsis cumingii cultured by the sediment of the shrimp ponds was the best in growth and shell color traits.This paper found that the effect of the aquifers and sediment on the shell color of Hyriopsis cumingii was significantly higher than that of growth traits.And the aquifers and sediment was the key factor affecting the shell color Hyriopsis cumingii.These results provided a theoretical basis for further development of inner shell color selection and demonstration of Hyriopsis cumingii.