Abstract
Enzyme loci Pgm1, Adh1, Phi1, Acp4, Est4, Pgd1, Pgd2, Got1, Mdh2, Est1, Acp1, Glu1 and Prx1 were assayed electrophoretically by using 100 seedlings each of eight populations: Mexican Super Dwarf, Chinese, Elite Composite, Composite population (Mexican Super Dwarf x Chinese) x Elite composite and two cycles of recurrent selection for yield-index in normal and dwarf sub-populations derived from the composite population. Departure from expectation of genotype frequencies in the composite population relative to the component populations suggested the effect of natural selection. Differences among populations in their allele frequencies were detected for the 13 enzyme loci assayed. Changes in allele frequencies in cycle-1 and cycle-2 for both sub-populations relative to the allele frequencies in the composite population suggested an effect of artificial selection on allozyme frequencies. The br$\sb2$ gene did not seem to influence this effect through linkage with allozyme alleles of loci Pgm1 and Adh1. Also a trial was conducted involving 200 S$\sb1$ families each of the normal and dwarf sub-populations of cycle-2, plus 10 checks of cycle-1, all grown at two plant population densities. A 14 x 15 rectangular lattice design was used. For both types of plants, family means for days to anthesis, plant and ear height, grain moisture, ears per plant, adjusted grain yield and yield-index differed significantly (P $<$ 0.01), indicating variability among families. High heritabilities suggest that further improvement can be made in both sub-populations. Means of cycle-1 and cycle-2 have been improved in the direction intended for adjusted grain yield and yield-index in both sub-populations and for days to anthesis in the normal sub-population. Families x density interactions were non-significant, indicating no differential effect of density on families. Density x stature interactions were also non-significant. Possibly these results are related through the association of selection for yield-index with changes in allozyme frequencies, suggesting linkage of allozymes with quantitative genes that affect the components of yield-index.
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Claims 10
Claim · model-written summary
Genotype frequencies in the composite population departed from component-population expectations.
Not reportedTaxon
Verbatim
e0“Departure from expectation of genotype frequencies in the composite population relative to the component populations suggested the effect of natural selection.”
Claim · model-written summary
Allele frequencies differed among populations at 13 assayed enzyme loci.
Not reportedTaxon
Verbatim
e0“Differences among populations in their allele frequencies were detected for the 13 enzyme loci assayed.”
Claim · model-written summary
Recurrent selection cycles changed allozyme allele frequencies relative to the composite population.
Not reportedTaxonDirection
Verbatim
e0“Changes in allele frequencies in cycle-1 and cycle-2 for both sub-populations relative to the allele frequencies in the composite population suggested an effect of artificial selection on allozyme frequencies.”
Claim · model-written summary
The br$\sb2$ gene did not seem to influence selection effects via linkage with Pgm1 and Adh1.
Not reportedTaxonDirection
Verbatim
e0“The br$\sb2$ gene did not seem to influence this effect through linkage with allozyme alleles of loci Pgm1 and Adh1.”
Claim · model-written summary
Family means differed significantly across anthesis, height, moisture, ears, yield and yield-index.
- Outcome
- family means for days to anthesis, plant and ear height, grain moisture, ears per plant, adjusted grain yield and yield-indexe0
Not reportedTaxon
Verbatim
e0“For both types of plants, family means for days to anthesis, plant and ear height, grain moisture, ears per plant, adjusted grain yield and yield-index differed significantly (P $<$ 0.01), indicating variability among families.”
Claim · model-written summary
High heritabilities suggest further improvement is possible in both sub-populations.
- Outcome
- High heritabilitiese0
Not reportedTaxon
Verbatim
e0“High heritabilities suggest that further improvement can be made in both sub-populations.”
Claim · model-written summary
Adjusted grain yield and yield-index improved in both sub-populations from cycle 1 to cycle 2.
Not reportedTaxon
Verbatim
e0“Means of cycle-1 and cycle-2 have been improved in the direction intended for adjusted grain yield and yield-index in both sub-populations”
Claim · model-written summary
Days to anthesis improved in the normal sub-population.
Not reportedTaxon
Verbatim
e0“and for days to anthesis in the normal sub-population.”
Claim · model-written summary
Family by density interactions were not significant.
- Outcome
- Families x density interactionse0
Not reportedTaxon
Verbatim
e0“Families x density interactions were non-significant”
Claim · model-written summary
Density by stature interactions were not significant.
- Outcome
- Density x stature interactionse0
Not reportedTaxon
Verbatim
e0“Density x stature interactions were also non-significant.”