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(Mexican Super Dwarf x Chinese) x Elite Composite: I. Allozyme assays of germplasms and derived populations. II. Recurrent selection for yield-index in normal and dwarf subpopulations
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.
Subject Area
Agronomy|Genetics
Recommended Citation
Pixley-Sinclair, Alfredo Leopoldo, "(Mexican Super Dwarf x Chinese) x Elite Composite: I. Allozyme assays of germplasms and derived populations. II. Recurrent selection for yield-index in normal and dwarf subpopulations" (1989). ETD collection for University of Nebraska-Lincoln. AAI9013623.
https://digitalcommons.unl.edu/dissertations/AAI9013623