Estimation Of Genetic Parameters And The New Variety Breeding Of Portunus Trituberculatus

With the rapid expansion and intensification of Portunus trituberculatus, variousquestions such as diseases, bad quality of larvas and less natural resources, have occurredand been serious, causing economic losses. They have become the limiting factors in thesustaining development of this program. At last, these questions are resolved by providedexcellent breeds provided by using the selecting breeding program. This paper mainlystudied the estimation of genetic parameters and the new variety breeding ofP.trituberculatus. The primary results were listed below.1Genetic varation study on the four geography population of P. trituberculatusThere are many relative fatness indices, which can be classified as ratios andresiduals. Le Cren’s relative condition factor Kn was recommended because of theirsmall system error.Based on carapace length and body weight of each swimming crabfrom four populations, Yalvjiangkou(YL), Laizhouwan(LZ), Haizhouwan(HZ),Zhoushan(ZS), relative fatness were conducted by Le Cren’s relative condition index. Inthe result of relative fatness analysis, YL>LZ>HZ>ZS. And there is significant difference（P<0.01）, betweenYLand ZS, on October.There is significant difference （P<0.05）between LZ and ZS, HZ and YL on October. Male is lager than female at relative fatnessof four populations, but there is no significant difference （P<0.05）on October.Therelative fatness at different stage of swimming crab is different, for example120days>100days>80days. The results provide a foundation for the selective breeding andculture.It is very important to analyse the body colour diversity of P. triuberbuculatus forresource conservation. In March2007,50individuals were collected individually from four wild geographic populations. In this research, discriminant analysis and One-WayANOVA analysis were adopted during the analytical process. Based on spot characters ofeach P. trituberculatus from four gulfs, cluster analysis and discriminant analysis wereconducted. In discriminant analysis, total accuracy rate of discriminant on female crabsfrom four gulfs was53.3%. The accuracy rate of Laizhou Gulf population was the lowestof30.0%, while that of Haizhou gulf population was the highest of83.3%. Thediscriminant functions of four gulfs were established, respectively. Results showed thatcarapace colour and spot were significantly different among four populations. There wasa tendency for difference in carapace colour and spot to decrease with culturing in thesame environment at four populations. In this study all results supported that body colourof P. triuberbuculatus is decided by genetics and environment. Moreover, environment ismain factor.2Estimation of genetic parameters for important economic traits of P.trituberculatusIn this paper, the heitability of P. trituberculatus in body weight, full carapace width,carapace width, carapace length and body height, were estimated by intra-groupcorrelation of full-sibs. A total of400matured crabs were taken from culture populations.100sires and300dams were mated in1×3, and13half-sib families and37full-sibfamilies were produced. About30individuals were randomly sampled in harvest on day80and120in age from each family and five traits were measured. Causal components ofphenotypic variance were calculated with the GLM procedure of SPSS software. Resultsshow that the heritability on day80and120ranged0.42-0.74and0.25-0.70, respectively.No significant difference was found in the heritability between maternal and paternalgenetic variance. However, the difference was significant in components variance offull-sibs within sires and dams. The values0.53-0.65and0.32-0.50on day80and120,respectively, from components of variance of full-sibs within sires and dams were precise and unbiased for the traitst. The study shows that the heritability in five growth-traits of P.trituberculatus is moderate.Matings and crosses within and among geographical different populations of P.trituberculatus were carried out in order to breed new strains.Nine populations of fistfilial generations have been obtained. Three populations,designated ZZ1,LL1and HH1,were from matings of wild populations of Zhoushan(ZS), Laizhou Bay(LZ), and HaizhouBay(HZ).Two populations, that is ZL1, LS1, were from cross between ZS and LZ. Twopopulations, that is HL1and LH1, were from cross between LZ and HZ. Two populations,that is HZ1and ZH1, were from cross between HZ and ZS. After analyzing five growthtraits, full carapace width, carapace width, carapace length, body height and body weightby ANOVA, we found some traits were significantly different among nine populations offist filial generations. There existed different extent heterosis（0.33%-46.12%）for growthof full carapace width, carapace width, carapace length, body height, body weight andlivability in first filial generation of four hybrids. Heterosis were different in differentcombinations and different trairts. Nine populations gained were considered as the basicpopulations to breed new strains. Increased Variation parameters in first filial generationof cross could be a very good potential for selecting new strains.3Establishment of pedigree breeding technique and application of P.trituberculatusIt is an important way of selecting breeding by establishing family. So pedigreebreeding technique was establised, including the method of mating design, parent craboverwintering, larvae rearing, juvenile crab culturing and traits measure. Ten families ofsecond generation of P. trituberculatus were established by using pedigree breedingtechnique. Among ten families, the order of the body weight isf9>f10>f1>f8>f4>f3>f2>f5>f7>f6, the order of the full carapace width isf9>f10>f1>f4>f8>f3>f2>J5>f7>f6, the order of the carapace width is f9>f10>f1>f8>f4>f3>f2>f5>f7>f6, the order of the Carapace length isf9>f10>f1>f8>f4>f3>f2>f5>f7>f6, the order of the body height is f9>f10>f1>f8>f4>f3>f2>f5>f7>f6, at120days. The family named f9and f10are significantly largerthan the other eight families in body weight（P<0.01）. For example f9is larger than f6with96.10%, than f7with76.87%in body weight, respectively. f10is larger than f6with72.77%, than f7with55.76%in body weight，respectively. So f9and f10can be believedthe family with best growth traits. Then half-sib families were established by usingpedigree breeding technique in order to study the inheritance of carapace colour and fleck.The carapace colour of fist filial generations show transgressive type and fleck showintermediate type. Paedomorphosis and growth of juvenile crab exsit maternal effect.4Stduy on techniques of two types of tags in P. trituberculatusIn June2010, the suitability of visible implant fluorescent elastomer (VIE) and shear appendagefor tagging P. trituberculatus was investigated. VIE were implanted at two body positions in differentstage. Feasibility was based on tag retention, and the effect of tagging site and juvenile size on growthand survival. The result show that ventral region is suitable to II and III period juvenile crab into whichVIE were injected, then the joint of swimming leg coax and carapace is suitable to IV and later IVperiod juvenile crab. Tag retention was more than80%for crabs molted twice, but tag retention waslower for crabs motled third. Compared their growth and mortality rates with those of anequal number of untagged crabs，the results showed that tags have no effect on growth orsurvival. As a result of the higher tag retention and faster rate of shear appendage tagging,this method is recommended for VII juvenile crab and older. That is more scientific andreasonable if two methods are combined to tag crab. The tagging method will benefit to select-breedingand enhancement of crab.5Analysis of growth and breeding value estimation of P. trituberculatus“Huangxuan No.1”In this paper, the growth performance, heitability and breeding value of P. trituberculatus were estimated by full-sibs family. A total of200matured crabs weretaken from core breeding population of the new variety of P. trituberculatus“HuangxuanNo.1”.50sires and150dams were mated in1×3, and20full-sib families wereproduced. About50individuals were randomly sampled in harvest on day80and100inage from each family and carapace width, body height, body weight were measured.Results show that the body weight increased16.20%and19.35%on day80and100daysold respectively compared with the natural population. The growth performance of P.trituberculatus “Huangxuan No.1” was more and more superior with culture days. Theheritability on day80and100ranged0.164-0.304and0.117-0.241, respectively. It meansfamily selection is effective ways for breeding of P. trituberculatus. Comparison ofselection efficiency based on breeding value or phenotypic value revealed that thebreeding value was better than the phenotypic value for growth tratits from11.1to19.38%. It was suggested that, the efficiency of breeding value-based selection washigher than that of phenotypic selection.