| 1. Shrimps, due to its use in aquaculture with many spices, both farmed in size and value, take a very important status, so the key steps promoting shrimp breeding and cultivation are looking for premium resources and distinct breeding. After the analysis of Macrobrachium nipponense, it's found that both in growth performance, but also in the genetic diversity are available information and technology, and its breeding, hybridization, polyploid technology etc have obtained some achievements. But in production areas for the understanding level still have much ascend space, and in resource investigation and germ plasm improvement cause more concern.2. Growth performance was compared four groups of F1 of Macrobrachium nipponense from Taihu Lake (T) and Poyang Lake (P) populations by complete diallel crosses. The results showed that the group of F1 from T (♀)×P (♂) (TP) had the largest body length and weight gain and fastest growing speed, which was significantly larger and faster than those of P (♀)×T (♂) (PT) and inbreeding groups. The coefficient of variation of PT group in length and weight increased accompanying with the increase of month age, while the growth coefficient of variation and discrete degree of TP group always kept lower among the four groups. The correlation of body length and weight accorded with the power function W=aLb with very high relativity. The relation of body length and weight inrcease accompanying with farming time met exponential relationship L/W=ced△t, and the related coefficient of TP and PT groups was significantly higher than that of inbreeding ones. All of above, the obvious heterosis in growth performance could be achieved through the cross of M. nipponense populations between Taihu Lake (♀) and Poyang Lake (♂).3. Genetic diversity and genetic structure of Macrobrachium nipponense (parents of Taihu Lake and Poyang Lake, F1 from diallel crosses) were analyzed by using 12 pairs of microsatellite markers primers selected. The results showed: the average number of alleles (Na) for 17.67 and effective alleles (Ne) for 12.48, between 112-427bp in size. Average observed heterozygosity (Ho) for 0.6938, and mean expected heterozygosity (He) for 0.9134. Six stocks of genetic differentiation index Fst value between stocks in 0.0234-0.0529, gene flow (Nm) in 4.4766-10.4117. The differentiation is not obvious. Clustering analysis results showed that TP (Taihu Lake♀×Poyang Lake♂) stock and PT (Poyang Lake♀×Taihu Lake♂) stock, TH (Taihu Lake parents) stock and TT (Taihu Lake♀×Taihu Lake♂) stock, PY (Poyang Lake parents) stock and PP (Poyang Lake♀×Poyang Lake♂) stock were gathered, respectively, and then, TP, PT, TT and TH gathered again, finally, with PY and PP gathered. Test results showed that observed heterozygosity of the hybrid stocks had increased obviously, but there was not obvious differentiation between hybrid stocks and other stocks. Furthermore, the hybrid progenies were more similar with the female parent in genetic structure. In this study, we analyzed genetic diversity and genetic structure between various stocks by hybridization for Macrobrachium nipponense, so as to providing theory basis for resources conservation and exploitation.4. In this study, by comparing length and weight of F1 bred from different specification paternal Taihu Lake groups of Macrobrachium nipponense, the result showed that F1 bred from big norms has better performance than that bred from lesser specifications in 60 d. TB combination had 2.42 % and 7.17 % higher in length and weight respectively than TS combination, and the increase of the ratio on length and weight, along with the cultivate time, had the tendency of expansion. In addition, to compare with the growth rate of length and weight, TB combination was larger than TS combination in the experimental period within 60 d. Both combinations had large change in body length coefficient of variation, as to the body weight coefficient of variation; TB combination was less than TS combination from 30 d up. Overall speaking, TB combination had lesser discrete degree and better performance in growth. |
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