Submitted to: American Journal of Plant Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/14/2014
Publication Date: 2/1/2014
Citation: Bunce, J.A. 2014. Corn growth response to elevated CO2 varies with the amount of nitrogen applied. American Journal of Plant Sciences. 5:306-312. Interpretive Summary: Higher carbon dioxide concentrations often reduce the nitrogen content of plants, and could increase the amount of fertilizer nitrogen required to achieve maximum crop yields, although this has not been tested under field conditions. This experiment tested this hypothesis in sweet corn grown in the field. It was found that corn crops grown at elevated carbon dioxide had a stronger response to nitrogen application rate, and had a higher nitrogen requirement than at the current atmospheric carbon dioxide concentration. This work will be of interest to crop scientists working to modify crop management systems for global change conditions.
Technical Abstract: Corn, with C4 photosynthetic carbon metabolism, often has no photosynthetic, growth, or yield response to elevated carbon dioxide concentrations. In C3 species, the yield stimulation at elevated carbon dioxide concentrations often decreases with nitrogen limitation. I tested whether such a nitrogen interaction occurred in corn, by growing sweet corn in field plots in open top chambers at ambient and elevated (ambient + 180 ppm) carbon dioxide concentrations for four seasons, with six nitrogen application rates, ranging from half to twice the locally recommended rate. At the recommended rate of nitrogen application, no carbon dioxide effect on production occurred. However, both ear and leaf plus stem biomass were lower for the elevated carbon dioxide treatment than for the ambient treatment at less than the recommended rate of nitrogen application, and higher than the ambient treatment at the highest rates of nitrogen application. There were no significant responses of mid-day leaf gas exchange rates to nitrogen application rate for either carbon dioxide treatment, and elevated carbon dioxide did not significantly increase leaf carbon dioxide assimilation rates at any nitrogen level. Leaf area index during vegetative growth increased with nitrogen application rate at elevated but not at ambient carbon dioxide, indicating that N was saturating to growth at ambient but not elevated carbon dioxide. It is concluded that elevated carbon dioxide increased the responsiveness of corn growth to nitrogen application by increasing the response of leaf area to nitrogen application rate, and that elevated carbon dioxide increased the amount of nitrogen required to achieve maximum yields.