Master of Science / Department of Agronomy / Johanna A. Dille / Corn yield potential is limited by water deficit stress and limited soil nitrogen. Field and greenhouse experiments were conducted near Manhattan, KS in 2005 and 2006. The field experiment evaluated the influence of nitrogen (N) rate and increasing Palmer amaranth (PA) density grown alone and in competition with corn in two moisture environments. In 2006 the dryland environment was very drought stressed, while 2005 had more intermediate conditions. Weed-free corn yields were approximately half in dryland environments compared to the irrigated environment across years. Increasing PA density increased corn yield loss similarly in both 2005 environments and in 2006 dryland environment across all N rates. In the 2006 irrigated environment corn yield loss was increased by decreasing N rate and increasing PA density. Maximum predicted yield loss at high PA densities in both 2005 environments was 20-54% while in 2006 dryland environment, maximum yield loss was 95% and in the irrigated environment was 62%. In general, soil moisture environment was more critical than N rate or PA density when determining potential corn yield. In the greenhouse study a factorial arrangement of two irrigation methods and five crop-weed combinations (corn, PA, GF, corn/PA, and corn/GF) was established with two replications and three runs conducted. Two plants were grown in 25.4 cm diameter PVC pipe cut into 91.5 cm lengths. Irrigation application method included a surface and subsurface application. Plants were harvested at the V10 corn growth stage. No differences were detected between irrigation methods with respect to above- or below ground biomass production. Corn aboveground biomass was decreased by the presence of corn or PA but not GF. Below ground biomass information was presented as column totals because species could not be separated. There was no impact on root to shoot ratio, total below ground biomass, rooting depth, or root area across the crop-weed combinations except for the GF monoculture columns which were lower than all other crop-weed combinations. Future research needs to examine the light interception of corn and PA when grown at different N rates along with examining the influence of surface and subsurface irrigation practices on crop weed interactions and weed seed germination in a field setting.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/425 |
| Date | January 1900 |
| Creators | Ruf, Ella Kathrene |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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