摘要
Sprague和Tatum(1942)提出的配合力概念(即一般配合力gi和特殊配合力sij)可用统计模型xij=μ+gi+gj+sij+eij表示,不考虑eij,则sij为xij偏离μ+gi+gj之差;杨允奎在其遗稿《玉米自交系数量性状遗传研究初步报告》中首次提出以xij偏离中亲值MP之差计算特殊配合力效应sij的简便方法(杨氏简法),即s′ij=xij-12(-xi.+-x.j)=sij+12(gi+gj),这两种特殊配合力的差异是由于表示这两种离差的原点不同所致。由于Sprague等的遗传假设不明确,所定原点不当,因而夸大了GCA而降低了SCA,不能真实地反应杂种优势。而杨氏所定义的特殊配合力与杂种优势完全一致,具有明确的遗传理论基础。此外,目前国内外广为采用的仍多为Griffing(1956)所提出的4种双列杂交方法,利用最小二乘法估计μ^、^gi、^gj和^sij。运用数量遗传学的原理和方法分析了Sprague等的直接定义法、Griffing的最小二乘算法和杨氏简法所得估算结果的异同及其相互间的代数关系,对于Griffing双列杂交试验的方法3和方法4,3种不同方法估算配合力效应值可以相互转换和验证。若以评价亲本育种价值为目的,3种方法所得结论一致;而以估计组合杂种优势为目的,则以杨氏简法最为可靠。
Combing ability including the general combining ability （GCA） and the special combining a- bility （SCA）, which was proposed by Sprague and Tatum （1942）, can be expressed as the following statistical model, xij =μ ＋ gi ＋ gj ＋ sij ＋ eij. SCA is the difference between the observed value xij and the sum of μ ＋ gi ＋ gj if the error item eij were not thought about. Another method of estimating SCA, firstly proposed in a paper ＂A preliminary report on the study of quantitative traits in corn inbred lines＂ written by Prof. Yang Yunkui in 1965, is defined as the difference between xij and the mean parents value （MP）, viz. s′ij = xij - 1/2（-↑xi. ＋-↑x.j） = sij ＋ 1/2（gi ＋ gj）. The two methods of estimating SCA differs from each other because the origins denote differently. GCA was enlarged and SCA was dwindled as the genetic hypothesis of Sprague＇ s definition of combining ability and the origin were improper, and the hybrid superiority was expressed truly. On the other hand, the Yang＇ s definition of SCA, which was consistent to hybrid superiority, possessed unambiguous foundation of genetic theory. Moreover, the most used method of calculating GCA and SCA is the one proposed by Gtiffing （1956） which adopted the least squares. By using the theories and methods of quantitative genetics, three methods and their relationship were analyzed and compared to understand the different results from method 3 and 4 of Griffing＇s diallel cross trials. To these trails, the results of GCA and SCA may be inter-transformed and inter-validated among three methods. If the object is evaluating the value of a series parents, three methods can yield the same conclusion. Otherwise, if forecasting hybrid superiority is the mainly object, the Yang＇s method of estimating SCA can be the most reliable.
出处
《四川农业大学学报》
CSCD
2006年第2期228-231,共4页
Journal of Sichuan Agricultural University
关键词
双列杂交
配合力
估算方法
diallel cross triM
combining ability
method of estimation
