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Genetic Variance Components and Predicted Response to Selection Under Selfing and Full‐sib Mating in a Maize Population 1
Author(s) -
Cornelius P. L.,
Dudley J. W.
Publication year - 1976
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1976.0011183x001600030005x
Subject(s) - overdominance , inbreeding depression , biology , selfing , inbreeding , dominance (genetics) , population , selection (genetic algorithm) , mating system , diallel cross , additive genetic effects , statistics , agronomy , genetics , heritability , mathematics , heterosis , mating , hybrid , demography , artificial intelligence , sociology , gene , computer science
Genetic and environmental variance components in maize ( Zea mays L.) Synthetic O.P. were estimated from covariances among 12 generations (1 noninbred, 7 sibmated, 4 selfed) in 1970 and 1971 experiments previously described (Crop Sci. 14:815–819). The results showed: a) significant variance due to multiple alleles for plant height and ear height in 1971 and for grain yield in a 2‐year analysis, b) significant variance due to dominance for plant height and ear height in 1971 and for grain yield in both years, c) satisfactory fit of an additive genetic model for percent moisture at harvest and percent oil, and d) significant lack of fit of an additive and dominance model for kernel weight. The additive, dominance, multiple‐allele model contains three additive components (σ 2 I , C, σ 2 A ) and 2 dominance components (µ 2 1 ,σ 2 D . The relative importance ofμ ∘ 1 2was roughly proportional to inbreeding depression previously reported.σ ∘ D 3was large for yield but negative for plant height and ear height.σ ∘ A 2for yield was negative and an estimate of average degree of dominance suggested extreme overdominance. This may result from repulsion phase linkages of loci showing partial to complete dominance. Predictions of response to selection for general combining ability (GCA) and performance of lines per se (LPS) suggested a) at equivalent levels of inbreeding, selection under the two systems will be about equally effective if there has been no prior selection, but cumulative response to selection would be 1.5 to 2.0 times as great under sib‐mating as under selfing, b) a given amount of cumulative progress will be reached at a lower level of homozygosity under sib‐mating, and c) for yield, if substantial improvement in both LPS and GCA are desired, both must be evaluated.