Upper Thermal, Salt Tolerance Traits And Early Growth Comparative Study Of Sinonovacula Constricta Selection Group And Family

Sinonovacula constricta is widely distributed in coastal areas of china.It is a traditional Chinese shellfish which can accommodate wide temperature and wide salinity. For a long time, The seed resource of S.constricta is mainly obtained by the semi artificial seed selection for a long time. And used for artificial seeding breeding of shellfish most also comes from cultured respectively too. As the years of artificial breeding,frequent inbreeding,led to a decline in species diversity, respectively germplasm resource degradation. Therefore, the genetic improvement for S.contricta and raised new varieties with fast growth speed and distinct individual character through artificial breeding is an important way to salve the problem. This article carries on a research from screening parents to establish a family, and choose the genealogy, On the basis of the selected high salt and high temperature resistance of the varieties, in order to lay the foundation for respectively germplasm improvement.To compare the early growth performance of the Sinonovacula constricta family group and colony group, we chose the excellent group from Leqing Bay to conduct the growth experiment. We establish a selection group and 27 full-sib families(F₁、F₂、…F₃₀). For the selection group, the control group is breeding population group. For the full-sib families, single pair method is applied. And analyses were done about the fertility rate, the metamorphosis rate, the adhesive rate, the growth rate and size specification in different term. By multiple comparison and variance analysis, it was indicated that there was no significant difference of the fertility rate, the metamorphosis rate, the size of D-type larva and the adhesive rate between different experimental groups（P>0.05）. For all the experiment groups, the individual size and growth rate are different in different development period. And the size and growth rate of group selection are bigger than these of breeding population with significant difference（P<0.05）. Among the full-sib families, there were also differences in the growth rate. Groups of F₂, F₇, F₉, F₁₃, F₁₉, shown greater growth vigor than the control group with significant difference（P<0.05）. Groups of F)5, F)6, F₁₄, F₂₅, F₂₇ shown growth disadvantage compared with control group, also with significant difference（P<0.05）. The paper conducted comprehensive comparison of early growth performance between family group and colony group, obtained the excellent family and colony.To investigate the relationship between growth properties and thermal and high salt tolerance in Sinonovacula constricta, We have established and obtained 27 families with different growth performance of S.constricta in 2014 based on the excellent group from Leqing Bay. Growth traits of different families were recorded in the first three months: Five families showed superior growth rate, seventeen families showed medium growth rate and five families showed inferior growth. After the next three months, five superior and inferior families were obtained respectively. In the preliminary experiment, the semi-lethal temperature and salinity of S.constricta are 36.5℃and 35.8 respectively. With the control group of group breeding S.constricta, each families were cultivated in the environment of normal salinity, 36.5℃water or normal temperature, 35.8 salinity respectively. To conclude, the survival rate of superior families was higher than the disadvantage families under the conditions of semi-lethal temperature and salinity and there was a significant difference in heat tolerance and salt tolerance among the different families studied（P<0.05） by multiple comparison and variance analysis. The strongest family were higher than the worst family by 74% and 50% respectively in upper thermal and salt tolerance.