A diallel cross is a mating scheme used by
plant and
animal breeders, as well as
geneticists, to investigate the genetic underpinnings of quantitative traits.
[Hallauer, A. R. and J. B. Miranda Filho. 1988 Quantitative genetics in maize breeding. 2nd ed. Iowa State University Press, Ames, IO.]
In a full diallel, all parents are crossed to make hybrids in all possible combinations. Variations include half diallels with and without parents, omitting reciprocal crosses. Full diallels require twice as many crosses and entries in experiments, but allow for testing for
maternal and paternal effects.
If such "reciprocal" effects are assumed to be negligible, then a half diallel without reciprocals can be effective.
Common analysis methods utilize
general linear models to identify
heterotic groups, estimate
general or
specific combining ability,
[Gardner, C. O. and S. A. Eberhart. 1966. Analysis and interpretation of the variety cross diallel and related populations. Biometrics 22: 439-452] interactions with testing environments and years, or estimates of additive, dominant, and epistatic genetic effects
[Hayman, B. I. 1954. The analysis of variance of diallel tables. Biometrics 10: 235-244] and genetic correlations.
Mating designs
There are four main types of diallel mating design:
# Full diallel with parents and reciprocal F1 crosses
# Full diallel as above, but excluding parents
# Half diallel with parents, but without reciprocal crosses
# Half diallel without parents or reciprocal crosses
References
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Genetics
Breeding