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|Title:||Using Geographically Diverse High-Protein Germplasm to Simultaneously Improve Yield and Protein Percentage in Soybeans (Glycine Max Merr.)|
|Author(s):||Korczak, Jeannette Frances|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Previously reported studies from a limited sampling of soybean germplasm have indicated that yield and protein percentage are negatively correlated. However, this may not reflect the situation present in the species as a whole.
The purpose of this study was to examine the correlation between yield and protein percentage in a larger, more diverse group of soybean populations than previously considered. Seventeen populations were obtained from crosses of the adapted cultivar 'Williams' with a group of geographically diverse, and presumably genotypically diverse, high-protein lines. F(,3) lines were obtained from each population and were tested in the F(,3) and F(,4) generations at Urbana, Illinois. Five populations were evaluated in 1979 and 1980, and the remaining 12 in 1980 and 1981. Data were collected for yield, protein percentage, and other agronomic and chemical traits.
For yield, protein percentage, and various other traits, the population means were similar to their midparent values, as would be consistent with an additive genetic model for these traits. Transgressive segregates for yield and protein percentage were also rare.
From the two-year analyses, broad-sense heritability estimates for yield ranged from 0.3 to 0.7 in the 5-population experiment, but many negative estimates were obtained in the 12-population experiment. Protein percentage had an average heritability of 0.8 in the 17 populations.
Significant negative correlations in excess of -0.6 were obtained between yield and protein percentage in only 5 populations. There was little evidence of any negative correlation in 7 populations, and several nonsignificant positive correlations as high as 0.25 were observed. However, a favorable correlation between the two traits did not guarantee that high-yielding, high-protein lines could be found within a population, since the amount of diversity and the level of performance for both traits were also important. Several populations having a negative correlation between the two traits were good sources of high-yielding, high-protein lines because of the population performance level for each trait.
Various selection indexes were examined for their utility in simultaneously improving yield and protein percentage. The economic weights indexes behaved similarly to selection for yield itself, whereas the desired gains indexes predicted moderate amounts of progress for both traits in certain populations.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
|Date Available in IDEALS:||2014-12-16|