Purdue University | Indiana CCA

Proceedings 2007

Indiana Certified Crop Adviser Conference


Corn Plant Population Response and Risk in the Northern Corn Belt

The optimum plant population for corn (Zea mays L.) production has been increasing due to improved stress tolerance at high plant population, lodging resistance, and the development of new transgenic traits that improves root and stalk integrity thus protecting yield. The objective of this presentation is to determine the optimum plant population, how much it has changed over time and describe risks associated with populations higher and lower than the optimum. Replicated data involving 632 hybrids were analyzed using 20 years (1987 to 2006) of experiments from 136 locations, primarily from the Midwest U.S.. Nearly 31% of the time, yield increased with increasing plant population over the range of plant densities evaluated. About 15% of the time, grain yield increased to an optimum and then decreased. Nearly 50% of the time, no significant relationship existed between plant population and grain yield. Only 4% of the time grain yield decreased with increasing plant population. Significant genotype X location interactions were observed indicating that optimum plant population for corn hybrids need to be “fine-tuned” for specific environments. Optimum plant population has increased over this time period in northern Corn Belt locations, and recommendations should be changed to reflect these higher optimum plant densities. An approach to determining the optimum plant population in relation to seed cost and yield response will be presented.


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Shawn ConleyJoe LauerProfessor
University of Wisconsin

Joe Lauer is a Professor in the Agronomy Department at the University of Wisconsin. At UW, he is responsible for developing education programs and materials on 1) corn hybrid selection, 2) the influence of management decisions on profitability and risk, 3) integrating changing technologies and cultural practices into corn production systems, and 4) assessing yield impacts of management and environmental factors during corn growth and development. Joe grew up in north central Minnesota and holds degrees from St. John's University and the University of Minnesota. From 1985 to 1994, he was faculty extension agronomist at the University of Wyoming. In 1994, Joe joined the Agronomy faculty at the University of Wisconsin as a corn extension agronomist.