尼罗罗非鱼与萨罗罗非鱼正反交鱼自繁后代F2耐盐性、生长性能及亲本对杂种优势贡献力的评估

Evaluation of the growth, salt tolerance and parents’ heterosis contribution in reciprocal hybrids F2 between Oreochromis niloticus and Sarotherodon melanotheron

  • 摘要: 为选育耐盐和生长兼优的罗非鱼,以原始亲本尼罗罗非鱼(Oreochromis niloticus)和萨罗罗非鱼(Sarotherodon melanotheron)为对照, 正交鱼(尼罗罗非鱼♀×萨罗罗非鱼♂)自繁第二代(F2)和反交鱼(萨罗罗非鱼♀×尼罗罗非鱼♂)自繁第二代(F2)为试验对象, 观察和比较他们在0、15、20及25盐度中的耐盐性和生长性能,并估算杂种优势及亲本的贡献力。结果如下:(1)盐度20~25是正、反交鱼的适宜生长盐度, 他们在这一范围盐度里的日均增重率为尼罗罗非鱼在盐度0下的75%左右、萨罗罗非鱼在盐度25下的4倍左右, 表明杂交后代的生长速度比较接近尼罗罗非鱼, 远优于萨罗罗非鱼。在盐度25条件下, 正交鱼比反交鱼生长快7%左右。(2)在盐度15与20下,生长速度和体重变异系数的杂种优势较明显,未发现不同盐度会导致正反交鱼成活率有显著变化。(3)不同亲本鱼类的强势性状, 如尼罗的快速生长、萨罗的高耐盐性, 对杂交后代的不同性状在不同盐度中有不同的贡献力。运用F1a1P1+a2P2所作的估算表明,对杂交后代在15~25盐度下的生长率, 尼罗的杂种优势贡献力比萨罗的大3~4倍;对杂交后代在25盐度下的耐盐性, 尼罗的贡献力几乎为零, 而萨罗的贡献力几乎为100%。

     

    Abstract: In order to select a good breed both with ideal culture performance and high salt tolerance, taking Nile tilapia (O. niloticus) and black-chip tilapia (S. melanotheron) as compared groups, two reciprocal hybrids, e.g., O. n. ♀×S. m. ♂ (F2) and S. m.♀×O. n. ♂ (F2) as trial groups, a comparisons were conducted under 4 salinities (0, 15, 20 and 25 ppt). The major results were: (1) Both O. n. ♀×S. m. ♂ (F2) and S. m.♀×O. n.♂ (F2) showed a better growth under 20 and 25 salinities, equal to about 75% of growth of O. niloticus under 0 salinity, and 4 times of growth of S. m. under 25 salinity. It indicated that the growth of hybrids close to O. n., but much better than S. m. Under 25 salinity, O. n. ♀×S. m. ♂ (F2) showed 7% faster growth than S. m. ♀×O. n. ♂ (F2). (2) under 15 and 20 salinity, the heterosis showed higher in growth rate and coefficient variation of body weight, and It was found that 0、15、20、25 salinity could not cause a significant difference in survival of two hybrids.(3)It is founded that, the superior traits from different parent fish species, such as the fast growth of Nile tilapia, and the high salt tolerance of black-chip tilapia, are of different contribution for different traits of hybrids under different salinities. Estimated by the formula F1a1P1+a2P2,the contribution for growth of hybrids from Nile tilapia is 3~4 times higher than that from black-chip in 15-25 salinity, and the contribution for survival of hybrids in 25 salinity is almost 0 from Nile tilapia, but 100% from black-chip.

     

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