Abstract
Corn, with C4 photosynthetic metabolism, often has no photosynthetic 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 mmol·mol-1) 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 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 more with nitrogen application rate at elevated than at ambient 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.
Highlights
There would be substantial environmental benefits to reducing the amount of nitrate and nitrous oxide lost to runoff, ground water and the air from agricultural ecosystems
This can result in lower tissue nitrogen concentrations required for maximum growth, but could result in an increase in the amount of applied nitrogen required for maximum yield [2,3], this has not been tested under field conditions
This work tested for an effect of elevated carbon dioxide concentration on the response curves relating the yield of sweet corn to nitrogen application rate under field conditions
Summary
There would be substantial environmental benefits to reducing the amount of nitrate and nitrous oxide lost to runoff, ground water and the air from agricultural ecosystems. Losses of these nitrogenous compounds increase with nitrogen fertilizer application rates, which may increase with rising atmospheric carbon dioxide concentrations. The concentration of nitrogen in plant tissue often decreases when plants are grown at elevated carbon dioxide concentrations [1] This can result in lower tissue nitrogen concentrations required for maximum growth, but could result in an increase in the amount of applied nitrogen required for maximum yield [2,3], this has not been tested under field conditions. This work tested for an effect of elevated carbon dioxide concentration on the response curves relating the yield of sweet corn to nitrogen application rate under field conditions
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