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|Title:||Characterization in the USA and Argentina of Maize Populations With Different Proportions of Flint-Dent Germplasm|
|Author(s):||Brun, Eduardo Luis|
|Doctoral Committee Chair(s):||Dudley, J.W.,|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The importance of maize (Zea mays L.) germplasm type to the differential nitrogen fertilizer response in the USA and Argentina and the value of the USA dent germplasm in maize breeding in Argentina have not been reported. Testcrosses to a flint and a dent tester of four maize populations with 100, 75, 50, and 25% of Argentine flint germplasm grown at two nitrogen levels were evaluated in both countries for grain yield and other agronomic traits.
In both countries, populations with increasing proportions of dent germplasm and the dent tester produced testcrosses with significantly higher means for grain yield at low and high nitrogen levels, average yield, and average relative N use efficiency but not for nitrogen response. The relative nitrogen response was 15% in both countries. The genetic variance for nitrogen response was significantly different from zero in the USA but not in Argentina. Nitrogen response and average relative N use efficiency show negative correlations when the genetic variance at high nitrogen is not greater than that at low nitrogen levels. This genetic correlation becomes less favorable as the difference in N rates between high and low N levels is increased. These populations may be better tested under higher than lower N environment in both countries.
The higher yields of the more dent-like populations may be explained by heavier ears, higher ear row number, and heavier and longer kernels. The maize population with 25% of flint germplasm seems to be the most suitable for developing high-yielding hybrids with good standability. The populations with higher percentage of dent germplasm and the dent tester showed lower means for kernel protein and oil percentage. Within a country, populations did not differ significantly for genetic variance and heritability estimates for any trait. Prolificacy showed the highest positive genetic correlation with grain yield in both countries and its use, as a secondary trait, could improve the efficiency of index selection of the populations with the flint tester in the USA. In Argentina, higher relative predicted gain for grain yield was obtained with the flint tester.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.
|Date Available in IDEALS:||2014-12-16|