Incorporation of Exotic Germplasm Into Adapted Maize Synthetics to Improve Grain Yield and Multiple Leaf Blight Resistance (Selection Response, Zea Mays, Quantitative Genetics, Corn)
Greder, Rodney Richard
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https://hdl.handle.net/2142/71624
Description
Title
Incorporation of Exotic Germplasm Into Adapted Maize Synthetics to Improve Grain Yield and Multiple Leaf Blight Resistance (Selection Response, Zea Mays, Quantitative Genetics, Corn)
Author(s)
Greder, Rodney Richard
Issue Date
1986
Department of Study
Agronomy
Discipline
Agronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Abstract
Population testcrosses to FRB73 and to FRMo17 of maize (Zea mays L.) populations containing 0, 25, 50, and 100% exotic germplasm, 80 to 100 random S(,1) families from each population, and the populations per se were evaluated for grain yield and aggregate leaf disease resistance. One cycle of divergent S(,1) family selection for each trait was conducted in the adapted, BC(,1)F(,2), F(,2), and exotic populations for three sets of crosses. Several suggested estimators of favorable alleles (i.e. Dudley's statistics (1p(,1)u, 1p(,1)u(,adj)), minimum upper-bound (m(UBND)/2), and predicted three-way (PTW/2)) were used in conjunction with other data to identify the most appropriate foundation population in which to initiate selection for grain yield.
Significant mid-parent heterosis and favorable values of the estimators indicate BS16 and PIC2 likely contain unique, favorable alleles and/or have high frequencies of favorable alleles at certain loci controlling grain yield. Larger C(,1) (cycle one) S(,1) means, improved C(,1) S(,1) distributions and larger C(,1) high yield synthetic means for the BC(,1)F(,2) suggest selection in the BC(,1)F(,2) to be superior to selection in the F(,2) for improving grain yield, in the short term, in adapted x exotic population crosses.
The exotic populations had 20 to 48% less leaf area infected by the multiple leaf blight pathogens than the adapted synthetics. Better gains from selection in the F(,2) in two of three crosses and significantly better C(,1) synthetic means for the F(,2) than BC(,1)F(,2) for all crosses suggest its appropriateness as a base population for incorporating favorable leaf blight resistance alleles. Low genetic correlations and favorable correlated responses indicate improvement in both grain yield and aggregate leaf blight resistance should be possible from selection in the F(,2) or BC(,1)F(,2).
Characterization of populations containing different proportions of exotic germplasm and the detection of response to selection in each using the suggested estimators was only marginally effective. Rankings of populations for grain yield were significantly correlated between the following estimates: population per se x (mean) with S(,1) x, x of top 10% S(,1)'s with FRMo17 testcross x, FRMo17 testcross x with 1p(,1)u, FRMo17 testcross x with 1p(,1)u(,adj), 1p(,1)u(,adj) with PTW/2, and 1p(,1)u with variance among S(,1) lines.
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