Degree Type


Date of Award


Degree Name

Master of Science



First Advisor

William Beavis


Increasing grain yield in soybean is an important breeding goal for plant breeders. While identification of yield QTL can result in identification of genomic regions for increasing yield, these regions are often not consistent across environments due to genetic and environment interactions. Water limitation for crop growth is one such environment in which yield QTL are not consistent. Water limitations during grain fill can be especially devastating to the final yield of a crop. The objective of this study was to identify and then map QTL in three families of recombinant inbred lines (RILs) developed from two plant introductions and one line originating from a commercial variety from the University of Missouri all crossed to IA3023. QTL mapping was done with yield data and ureide concentration. One set of data was obtained from a small field study in Nebraska created for the purpose of limiting water to the crop. The second set of data was opportunistic data from a larger study spanning many states in the Midwest over 3 years. For QTL mapping, the families included F5 lines developed using IA3023 as the common crossing parent and selected for similar maturity. The three families were created with PI 427.136, PI 404.188A, and LD00-3309. The three bi-parental populations were evaluated with 4,363 informative SNP markers for yield and ureides during 2 years in Lincoln, Nebraska and for yield and 3 years at 9 locations across the Midwest. Genotypic and phenotypic data were analyzed using rQTL to identify major QTL. Clustering environments was used in the larger dataset for separation of like environments. Two phenotypes focused on QTL mapping. Those were ureide levels and grain yield. For water limited and adequate water environments 23 QTL were identified through both studies for ureides and yield.


Copyright Owner

Dawn Gibson



File Format


File Size

93 pages