Diallel Analysis Models: A Comparison of Certain Genetic Statistics

Abstract

ReseaRchD iallel mating design is often used by plant and animal breeders to generate genetic information that can be used for devising breeding strategies. Crop breeders would like to know if genetic parameters or statistics obtained from different diallel methods developed by Griffing (1956) and Gardner and Eberhart (1966) and from the diallel experiments with different numbers of parental lines yield the same, similar, or different results. Such information would not only be useful for researchers in selecting the most appropriate diallel method, but it would also be valuable in determining if the results from other diallel studies with different numbers and different sets of parental lines could be used as reference in our own crop breeding programs.Several key studies relate to diallel mating designs (e.ABSTRACT Diallel analyses, although popular, raise key questions: (i) Do genetic statistics from different diallel methods with same and different sets of lines offer the same or similar information? and (ii) Would lack of information on reciprocal (REC) and maternal (MAT) effects in certain diallels put breeding programs at risk? To answer these questions, general (GCA) and specific combining ability (SCA), MAT, and REC effects were calculated from diallels with 12, 10, 8, 6, and 4 maize (Zea mays L.) parents. We found that with the same lines, the signs and magnitudes of GCA effects were similar and highly correlated among Griffing's Methods 1, 2, 3, and 4 and identical between Griffing's Method 4 and Gardner and Eberhart analysis III (G&EIII). The SCA effects from Griffing's Methods 1 to 4 were correlated. Griffing's Method 4 produced SCA effects identical to G&EII and G&EIII; SCA effects from Griffing's Methods 1 and 2 were upwardly biased because of inclusion of parental lines. Griffing's Method 3 (no parents included) was the best method among all six methods; it gave unbiased SCA estimates and information on MAT and REC effects. With different numbers of lines in diallel crosses, genetic statistics could serve as references across breeding programs because the signs of GCA and SCA effects were mostly same; however, caution must be exercised because some effects with opposite signs were detected. A diallel method that does not provide REC and MAT information could miss identifying superior hybrid(s). Because Methods 1 and 2 provided upwardly biased estimates of GCA and SCA effects, they are not recommended for estimation of GCA and SCA effects. We also concluded that Method 3 was the best diallel method; it provided unbiased estimates of SCA effects and also provided crucial REC and MAT effects, which are useful for proper selection of male and female parents in hybrid development.

Reciprocal Diallel Crosses Impact Combining Ability, Variance Estimation, and Heterotic Group Classification

“…have allowed researchers (e.g., Yao et al, 2013) to estimate related genetic variances among different diallel methods.…”

“…Griffing's methods have become popular among plant breeders to determine GCA and SCA effects in maize Kang et al, 1999Kang et al, , 2005Phumichai et al, 2008;Yao et al, 2013) and other crops (Ragsdale and Smith, 2007;Zwart et al, 2008;Yang and Gai, 2009;Velu et al, 2011;Berger et al, 2012). The GCA and SCA effects have been further used for genetic diversity evaluation, inbred line selection, heterotic pattern classification, heterosis estimation, and hybrid development (Sughroue and Hallauer, 1997;Fan et al, 2002;Melani and Carena, 2005;Barata and Carena, 2006).…”

Effects of open- and self-pollination treatments on genetic estimations in maize diallel experiment

“…Griffing's method 3, model 1 was applied for the diallel analyses (Griffing, 1956a,b), since it offers better estimation with less biased genetic calculations compared to other Griffing methods (Yao et al, 2013). Statistical analyses were based on the following model:…”

“…Although the effect of different pollination treatments on several biochemical traits in maize has been investigated, the effects on genetic calculations in diallel mating are still unclear. Almost all studies comparing genetic estimations in diallel analyses are based on contrasting statistical models and methods (Yao et al, 2013;Fan et al, 2014). However, a significant effect on the kernel structure resulting from the selected pollination treatment has been suggested as possible by Letchworth & Lambert (1998) and Krieger et al (1998).…”

Pendugaan Daya Gabung dan Heritabilitas Beberapa Karakter Agronomis pada Populasi Generasi F1 Kakao (Theobroma cacao L.)

“…Keberhasilan program tersebut sangat dipengaruhi oleh ketersedian sumber daya, tujuan, dan perilaku genetik dari sifat-sifat unggul yang diinginkan (Yao et al, 2013). Oleh sebab itu, pengetahuan mengenai parameter genetik seperti daya gabung dan daya waris suatu sifat unggul sangat penting.…”