Corn breeders bring their high density corn research to Monmouth

In 2013, the Northwestern Illinois Agricultural Research and Demonstration Center (NWIARDC) was one field location for a research study in which graduate student Sarah Potts (under the direction of Dr. Martin Bohn, University of Illinois Associate Professor in Quantitative Genetics and Plant Breeding, and Dr. Rita Mumm, University of Illinois Professor Emeritus in Quantitative Genetics and Plant Breeding) is working to identify corn genes involved in high plant density tolerance. Mrs. Potts recently answered a series of questions about this research project:

Why study plant density tolerance in corn?

Previous yield increases in corn have largely been the result of increased yield per unit area and not individual plant yield potential. This suggests that future yield improvement lies in the ability for crops to maintain yield under higher plant densities.

How many years did it take for you to get to the field trial stage?

Brian Mansfield, the Research Agronomist at the NWIARDC worked on his Master's degree for 3 years researching plant density tolerance as a precursor to the research I am currently pursuing. From the results of Brian's research, we were able to determine which traits were truly important for observing responses to plant density tolerance, as well as which inbred parents to choose to develop my research population.

Where does the NWIARDC field trial fit in the larger project?

It took two years and over 150,000 hand pollinations to create the 320 hybrids used for these trials (Figure). Our first two trial locations were grown during the 2012 growing season, and we tested an additional three trial locations, including the NWIARDC, during the 2013 season. Each plot was a hybrid test-cross, of which there were a total of 320 hybrids. Each hybrid plot was grown once in each of the three replications under high planting density of 47,000 plants per acre (Figure).

What types of phenotypic data did you collect in Monmouth?

The data collected in Monmouth included plant and ear heights, leaf angle, upper stem diameter, stay green, barrenness, lodging, and grain yield and moisture.

Please explain how the lab and field work you are doing fit together.

The simplest way to explain this work is to describe it as correlation. By looking at the trends in the phenotypic data, and seeing what trends are also present and corresponding in the genotypic (genetic) data, we can identify which segments of the corn genome are likely contributing to the physical responses we observed in the field. For example, if hybrids A and B, but not C, are top yielding hybrids under high planting density (47,000 plants per acre), and both A and B, but not C, share a certain allele in the genome, we might conclude that this allele is a genetic contributor to the effect. Except, of course, this example scales up to 320 hybrids and breaks down into multiple traits with a set of over 12,000 molecular markers to test for correlation.

What do you hope to do with the results of this research?

One of the main deliverables from this research is the identification of molecular markers for use in selection during the breeding process. Eventually, a training population could be created to implement a genomic selection program. Additionally, the results from this research will be an indicator of which traits are truly important to measure in breeding programs specifically targeting plant density tolerance. The corn breeding industry is highly interested in plant density tolerance research, and many companies are already conducting their own plant density tolerance research.

For more information:

For more information, contact Sarah Potts by phone through the Department of Crop Sciences (217) 333-3420 or by email: The University of Department of Crop Sciences website has additional information about crop genetic improvement.