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提出了一种新的体系以确定如何同时考虑几种性状来选择林木单株或家系。这种新体系在三个方面不同于选择指标体系:(1)运用了多重计算与多重选择;(2)选择总是在单个性状基础上选择出最好的林木;(3)采用的性状内的相关仅基于所选择的家系。其数据是收集抽芽期、直径、树高、垂直高以及南伊利诺斯两个黑胡桃种子园内优势木的数量。在四种选择水平上,将遗传力、选择差以及性状内的相关的所有选择组合加以综合计算,得出标准单位上总的遗传增益。对于五种性状的最佳组合(每种性状选择家系的百分数)是随选择水平以及所研究的种子园而变化的。本文将对经济上的以及把此方法引入实践中的其它方面进行讨论。
A new system was proposed to determine how to consider several traits at the same time to select individual trees or pedigree. This new system differs from the selection index system in three ways: (1) multiple computations and multiple selections are used; (2) the best forest of choice is always selected on the basis of individual traits; (3) The correlation is based only on the selected pedigree. The data is collected during the budding period, diameter, tree height, vertical height, and the number of dominant wood in two black walnut seed orchards in southern Illinois. At all four selection levels, all combinations of heritabilities, selection differences, and all pertinent within the trait are combined to give the total genetic gain over the standard unit. The best combination of five traits (the percentage of families selected for each trait) varies with the level of selection and the seed orchard in question. This article will discuss the economics and other aspects of introducing this approach into practice.