Bernardo R
Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108, USA.
Theor Appl Genet. 2003 Nov;107(7):1252-6. doi: 10.1007/s00122-003-1375-0. Epub 2003 Aug 19.
Some breeders select inbreds from many F(2) or backcross breeding populations, each with relatively few progenies. Other breeders select inbreds from only a few breeding populations, each with many progenies. My objectives were to: (1) determine the relative importance of parental selection, number of breeding populations, and size of each population, and (2) find optimum combinations between number and size of breeding populations. I assumed that a breeder has resources to test a total of 2,000 recombinant inbreds for a quantitative trait that was controlled by 100 additive loci and had a heritability of 0.20, 0.60, or 1.0. The parental inbreds had an inherent pedigree structure due to advanced cycle breeding. The parental inbreds were ranked according to their mean performance, and breeding populations were made among all parents, the top 25% of parents, and the top 10% of parents. I found that the issue of number versus size of breeding populations was only secondary compared with the ability to identify, prior to making the crosses, the breeding populations with the highest mean performance. For a given level of effectiveness of parental selection, the selection response was largest when the maximum number of breeding populations was used. The effect of the number of breeding populations was minor, however, when selection was practiced among the parents or when heritability was less than 1.0. The results suggested that, in practice, large selection responses could be obtained with a wide range of combinations between number and size of breeding populations.
一些育种者从许多F(2)或回交育种群体中选择自交系，每个群体的后代相对较少。另一些育种者仅从少数育种群体中选择自交系，每个群体有许多后代。我的目标是：(1)确定亲本选择、育种群体数量和每个群体规模的相对重要性，以及(2)找到育种群体数量和规模之间的最佳组合。我假设一位育种者有资源对总共2000个重组自交系进行一个数量性状的测试，该性状由100个加性基因座控制，遗传力分别为0.20、0.60或1.0。由于先进的轮回育种，亲本自交系具有固有的系谱结构。根据亲本自交系的平均表现进行排名，并在所有亲本、前25%的亲本和前10%的亲本之间构建育种群体。我发现，与在杂交前识别平均表现最高的育种群体的能力相比，育种群体数量与规模的问题只是次要的。对于给定的亲本选择有效性水平，当使用最大数量的育种群体时，选择反应最大。然而，当在亲本之间进行选择或遗传力小于1.0时，育种群体数量的影响较小。结果表明，在实践中，通过育种群体数量和规模的广泛组合可以获得较大的选择反应。
