Genetic Diversity Of The Large Yellow Croaker From Surrounding Zhou Shan Waters And The Research Of Growth Traits Of Family

In recent years, due to parent fish used for the large yellow croaker (Pseudoseiaena crocea R.) cultured was single source. It not only cause inbreeding is too frequent to make large yellow croaker germplasm degradation problems increasingly serious, but also directly affects the yield and quality of large yellow croaker cultured. At present, the population of large yellow croaker appeared a trend of younger age, miniaturization, growth speed is slow, and so the performance for the growth of large yellow croaker the breeding of good quality is necessary. In this paper, the research object of Zhou Shan surrounding of the group to build large yellow croaker, the research content is divided into genetic diversity of family parents related groups and related research which to find growth performance of family.Firstly,genetic diversity of family parents related groups:In this paper, eight microsatellite polymorphism markers were used for three populations of P.crocea in Zhou Shan area to research genetic diversity. For each locus,5～10alleles were amplified, adding up to64alleles in all the3populations. Average observed and expected heterozygosities (Ho and He) were0.9111and0.8108. Average polymorphism information content (PIC) is0.7800. The results show that the three P. crocea populations remain high genetic variation. Average observed heterozygosis and expected heterozygosis of three groups were0.8917,0.9000,0.9417and0.7384,0.7432,0.8213. Shannon diversity index were1.4670,1.4490,1.8009. All those shows that the genetic diversity at a higher level of three populations of P. crocea. In addition to LYC0015and LYC0009, the observed allele frequency of most of microsatellites loci deviated from Hardy-Weinberge equilibrium. According to the results of clustering analysis of the three groups, Daishan Cultured population and Zhujiajian Xi’ao cage farming population were genetically close while Zhujiajian Xi’an population and F2offspring of cold tolerance population from Fisheries Institute of Zhou Shan were distant.Secondly, this study selected Daishan and Zhujiajian population pointed to build test family using directional mating of nested design.12groups were structured successful, at the same time, using cultivation standardization to the five times for the large yellow croaker seedling in early seedling stage. In this paper, each of the department of spawning of family is16.39～32.64g, the highest spawning for more than double the amount of minimum laying eggs. Fertilization rate was24.88～29.79%, the hatching rate was28.14～30.00%. Results show that the large yellow croaker fertilization rate and hatching rate were low (not greater than30.00%), the main reason may be related to sperm or eggs in the process of building a family of large yellow croaker mother was of poor quality. At the same time, the study standardized cultivation five times at the large yellow croaker early seedling stage of seedling. The results show that although the most of survival rate of the standardized cultivation is high (>80%), only the survival rate of Zz2family is low (78.75%). But in standardization, the primary and secondary part number of standardization between families still different obviously, this may is associated with the gonad maturity and the environment were different. The main reason probably is large yellow croaker gonad maturity difference in the process of building a family, so the mastery of gonad maturity in the process of building large-scale family is a difficult, in addition to the better initial build synchronicity of family, the better environmental effect of each of the department of standardization.Thirdly, on account of standardization cultivation, the influence of environmental factors cause the properties of different about family growth differences can be neglected. In this paper, we study the growth traits of the standardized cultivation of12groups of family. Analysis of body quality difference, we fund the part of the family exist significant difference, and the part of the other is not significant difference;6,9and3months, Ddl family groups body quality is biggest,it bigger than the smallest body quality of family76.52%,32.21%and108.77%, respectively. The growth traits difference of Ddl family was significant. At the same time, analysis of3～6months of age,6～9months and3～9absolute growth rate of body length and weight, the absolute growth rate of Ddl family is maximum. Comparing the weight parameters and absolute growth rate, the DS of the source for the female parent group is bigger than the source of the female parent of ZJJ group. The results show that most of the family showed maternal effect. Breeding the good growth performance of family, the female parent from the better growth traits daishan groups of family is more conducive to economic value. The Ddl family was selected growth traits are relatively good family, providing reference for later family screening.At last, the article researched the path analysis of body length, body height and weight of large yellow croaker, size analysis and tests its significance and linear relationship and the related significance and linear relationship test. The results show that the correlation coefficient of body length and weight is the largest,0.947and0.934, respectively. The correlation coefficient of body height and weight were0.881and0.815, respectively. The correlation coefficient body length and body height is the smallest,0.859and0.787, respectively. Analysis of body length and body height of large yellow croaker weight directly affect significantly (P<0.01);The path coefficient of body height, body length size for body weight at the3month age is0.258,0.726,respectively. The path coefficient of body height, body length size for body weight at the9month age is0.210,0.769, respectively. The results of t test show that length and body height is no multicollinearity (VTF=3.810<10). So that at the early seedling stage of large yellow croaker (3,9month age), weight-related, body length and body height can be determined two indicators to research on the properties of large yellow croaker family, and on the growth performance comparison is given priority to with body weight, again to body length, last to body height.