| Luster is the index to measure the upper limit of pearl value.Improving the luster of cultured pearls is not only the focus of pearl industry,but also the innovation of pearl scientific research.In this study,white mussel(Hyriopsis cumingii with white inner shell main color)was used as material to analyze the correlation between shell color and inner shell luster at different months of age,and obtain the color parameters significantly related to inner shell luster,as well as the best month age for indirectly breeding traits to improve inner shell luster.On this basis,shell length and shell cyan were used as selection traits,Different selection strategies were set up to establish the population of slice feeding mussel and Pearl feeding mussel,carry out combined core insertion,study the influence of slice feeding mussel and Pearl feeding mussel of H.cumingii on the luster of nucleated pearls,analyze the correlation between the quantitative characters of Pearl feeding mussel and slice feeding mussel and the luster of pearls,and compare the luster of pearls produced by different pearl feeding combinations,It is expected to provide practical and theoretical basis for determining the breeding target traits of improving pearl luster and developing improved varieties of Pearl H.cumingii with high luster.1.Correlation analysis between shell color and inner shell luster of H.cumingii at different monthsTaking white mussel(H.cumingii with white inner shell as the main color)as the experimental material,30 white mussels were randomly selected at the ages of 4,5,6,7and 14 months to measure the shell color parameters and inner shell luster,and analyze the correlation between them.40 white mussels were randomly selected to measure the shell color parameters at the ages of 4,5,6,7 and 14 months,and the inner shell luster at the age of 14 months.The correlation between the shell color at each month and the inner shell luster at the age of 14 months was analyzed.It was found that the shell color parameters L,a,b and d E of white mussel at the age of 5 months were significantly correlated with the inner shell luster(P < 0.01),and the correlation degree was the largest compared with each month,and the correlation coefficients were-0.549,-0.66,-0.664 and 0.614 respectively.The shell color parameters L、a、b and d E of white mussel at the age of 5 months were significantly correlated with the inner shell luster at the age of 14 months(P < 0.01),The color parameters are most significantly related to the luster of the inner shell.The comprehensive results showed that taking the shell color dark cyan as the indirect selection character at the age of 5 months could improve the luster advantage of the inner shell of white H.cumingii2.Breeding of high luster strains of H.cumingiiEight groups of H.cumingii populations were established by using white mussel(H.cumingii with white inner shell as the main color)as the experimental material,shell length and shell cyan as the selection traits,and setting different selection strategies.The growth,shell color and luster of each population were measured.It was found that at the age of 14 months,there were significant differences in growth characters and inner and outer shell color parameters among groups(P < 0.05).Among the 8 groups,group IV had the best growth character and group I had the best inner shell luster.The inner shell luster of group I was significantly higher than that of group VII and VIII by9.78% and 15.18% respectively.The inner shell color of group I was the bluest and monotonous,with the largest L value,the smallest d E value,and the smallest a and b values;The shell color of group I is the darkest and richest,with the lowest values of L,a and b and the highest value of d E.At the age of 32 months,there were significant differences in the length character,shell height parameter and inner shell color character a parameter of each group(P < 0.05).Each group of H.cumingii was used as donor clam and pearl oyster respectively for combined nuclear insertion.After 18 months of cultivation,it was found that among the different pearl raising combinations,the pearl luster value of YAA pearl raising combination with donor clam and Pearl raising clam from the selected population of group I was the largest,which was 15.46% and 21.51%higher than that of YGG and YHH respectively.In the early stage,the shell color of group I selection population is cyan,and the luster characteristics of inner shell are outstanding.The pearl luster produced by core insertion is excellent,which can be used as a high luster strain of H.cumingii.Selection strategy I can be used as an effective reference strategy for directional breeding of high luster strains.3.Correlation analysis between growth,color and luster of donor mussel and the luster of nucleated pearlIn the overall experimental design of experiment 2,the relationship between the quantitative traits of the donor mussels and the pearl luster was analyzed simultaneously.There were significant differences in the luster of pearls cultivated by different groups of donor mussels(P < 0.05).The color parameters L,a,b and d E of the inner shell of donor mussels were significantly correlated with the luster of pearls(P < 0.01).The correlation coefficients were 0.691,-0.618,-0.603 and-0.648 respectively;The shell color parameters L,a,b and d E were significantly correlated with pearl luster(P < 0.01),and the correlation coefficients were:-0.686,-0.570,-0.547 and 0.646 respectively;There was a very significant positive correlation between inner shell luster and pearl luster(r = 0.717 ～ 0939,P < 0.01).The regression equation between inner shell luster and pearl luster was established as follows:,there was no significant correlation between growth traits and pearl luster(P > 0.05).The above results show that the breeding of H.cumingii with green shell color at the young mussel stage has achieved the goal of improving pearl luster,which can be used as an indirect trait for breeding H.cumingii with high luster.The inner shell luster of H.cumingii is significantly correlated with pearl luster,and the inner shell luster is better as the target trait.4.Correlation analysis between growth,color and luster of host mussel and the luster of nucleated pearlIn the overall experimental design of Experiment 2,the relationship between the quantitative traits of the host mussels and the pearl luster was analyzed simultaneously,and the relationship between the pearl luster and other traits of the pearl itself was analyzed.The results showed that there were significant differences in the luster of pearls cultivated by different groups of host mussels(P < 0.05),but there was no significant correlation between the growth traits,inner shell luster and inner and outer shell color of host mussels and Pearl luster(P > 0.05).In the characteristics of pearls,it was found that the color parameters L,a,b and d E had very significant correlation with pearl luster(P < 0.01),and the correlation coefficients were 0.740,-0.838,-0.779,-0.818,the size,roundness,weight and nacre thickness of pearl had no significant correlation with pearl luster(P > 0.05).The above results show that the quantitative traits such as growth and color of host mussels at the age of 32 months can not be used as a reliable index for selecting pearl luster traits,and the color trait of pearl white and green can be used as the target trait for breeding high luster white pearls. |
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