Breeding Of Hyriopsis Cumingii’ Shenzi No.1 ’F2 Generation And Evaluation Of Pearl Insertion Effect By Classification Combination

The color of pearls significantly affects the value of pearls,and rare freshwaterpurple pearls have higher value.Hyriopsis cumingii’Shenzi No.1’is the first new freshwater pearl clam bred in China,and the proportion of purple pearl is 45.8%.The promotion of this new variety has realized the mass production of fresh water purple pearl.In order to further improve the specification and color characteristics of the pearl produced by H.cumingii’Shenzi No.1’,In this laboratory,the characteristics of shell width and deep purple of inner shell were used as breeding indexes to further select and breed’Shenzi No.1’to"F₂"generation of H.cumingii In this study,the effects of genetic improvement on growth traits and shell color traits in F₂generation and F₁ generation of H.cumingii’Shenzi No.1’were compared.In addition,the F₂ generation of’Shenzi No.1’was selected by grouping breeding,and the dominant group with more purplish inner shell color and the dominant group with larger individual size were selected as the specialized strains of supply mussel and breeding mussel,respectively,In addition,the effect of different combinations of two groups of mussels was evaluated to lay a foundation for the selection and breeding of H.cumingii specialized strains.The results are as follows:1.Genetic improvement effect in F₂ and F₁ generations of H.cumingii’Shenzi1’According to the shell color and size,according to the compound breeding method,the F₁ population of H.cumingii’Shenzi No.1’was used as the F₂ parents,and the F₁ parents were not selected as the control group,with the seed retention rate of1%.Synchronized breeding of F₂ and F₁ generations of H.cumingii’Shenzi No.1’,The effects of genetic improvement on growth traits and shell color traits were evaluated at2,5 and 12 months of age,respectively.At 2 months of age,shell length,shell width,shell height and body weight of F₂ generation were significantly increased by 7.96%,9.46%,13.48%and 19.87%compared with F₁generation（P<0.05）;At 5 months of age,the shell length,shell width,shell height and body weight of F₂generation of’Shenzi No.1’were increased by 11.06%,15.40%,10.54%and 15.84%compared with F₁ generation（P<0.05）;The data of shell length,shell width,shell height and body weight of F₂ generation of’Shenzi No.1’were increased by 7.03%,10.16%,7.15%and9.73%compared with F₁ generation at 12 age（P<0.05）.At 12 years of age,L*,a*and DE*values of inner shell color of F₂ generation were significantly increased by 4.62%,12.31%and 3.11%compared with F₁ generation,respectively,and there was no significant difference in b*value（P>0.05）.In conclusion,significant genetic improvement effects have been achieved in growth traits and purpleness of shell after breeding of H.cumingii’Shenzi No.1’F₂ generation.2.Evaluation of the effect of the F₂ generation classification and combination of H.cumingii’Shenzi No.1’on pearl insertion and breedingIn April of 2018,the F₂ generation mussels of H.cumingii’Shenzi No.1’were bred.According to the inner shell color and size,the group with advantage of purple inner shell color（P）and the group with advantage of larger body size（G）were selected.After rearing for one year,for evaluating the effect of combination implantation,the mussels were implanted nuclei and saibo and three combinations with host mussel and donor mussel were obtained.They were donor mussel P×host mussel G combination（PG）,donor mussel P×host mussel P combination（PP）and donor mussel G×host mussel G combination（GG）.The unselected F₂ generation mussels of H.cumingii’Shenzi No.1’,as the control group,were implanted simultaneously.Before pearl implanting,shell length and shell height in P group were 1.72%and 1.45%higher than those in control group（P<0.05）,and color parameters a*,b*and d E*were 16.04%,126.71%and17.99%higher than those in control group（P<0.05）,respectively.The shell length,shell width,shell height and body weight in G group were 11.04%,11.46%,5.84%and 10.73%higher than those in control group（P<0.05）,respectively.The color parameters a*,b*and d E*were 9.89%,101.30%and 7.05%higher than those in the control group（P<0.05）.After 1 year of pearl implanting,Pearl color from the combination of PG and PP composite d E value is significantly higher than CC combination and GG combination（P<0.05）,and combination of PG and pearl color L*value from the PP composite was significantly lower than the CC combination and GG combination（P<0.05）,PP pearl color from the combination and GG combination b*value is significantly higher than CC combination and PG（P<0.05）,of which the PG pearls from the combination of d E*than CC combination and GG combination increased by 5.07%and 4.14%respectively,PP combination of pearl d E*than CC combination and GG combination increased by5.62%and 4.69%respectively.The diameter and nacre thickness of PG combination were increased by 6.50%and 9.77%（P<0.05）compared with CC combination,respectively.Compared with CC combination,the diameter and nacre thickness of GG combination were increased by 11.23%and 25.24%（P<0.05）,respectively,while the nacre thickness of PP combination was not significantly different from that of CC combination.The results showed that the comprehensive quality of pearls was the best.The color and size of pearls produced by PG combination were better,The PG combination was donor mussel P×host mussel G combination,the H.cumingii with good growth characteristics was used as the host mussel,and the H.cumingii with good inner shell color characteristics was used as the donor mussel.And the results laid a theoretical foundation for the development of specialized strains of supply shellfish and specialized strains of breeding pearl shellfish.3.Effects of classification and combination of H.cumingii pearl insertion on growth of H.cumingiiIn this study,growth data were measured for 3 beading combinations 4 and 12 months after the visceral mass beading operation.The results showed that the shell width and body weight of the GG and PG combinations were significantly higher than those of the PP combinations（P<0.05）4 months after implantation of visceral mass beads.Compared with PP combination,GG combination increased by 4.57%and 12.85%in terms of shell width and body weight,and PG combination increased by 4.65%and 7.51%in terms of shell width and body weight.The data of shell length and shell height of GG and PG were significantly higher than those of PP 12 months after implantation of visceral mass（P<0.05）.The data of shell length and shell height are increased by 3.41%and 4.22%respectively by GG combination and 2.94%and 3.40%respectively by PG combination compared with PP combination.The body weight data of GG combination was significantly higher than that of PP combination（P<0.05）,and the weight data of PG combination was not significantly different from that of PP combination（P>0.05）.The body weight of PG and GG groups was significantly higher than PP group 4 months after implantation of visceral mass beads.However,12 months after the implantation of visceral mass beads,the weight data of the GG combination and the PP combination were significantly different,the weight data of the PG combination and the PP combination were not significantly different,and the weight data of the PG combination and the GG combination were not significantly different.In conclusion,different combinations have certain effects on the growth of host mussel,but it is not significant.