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.
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Claims 8
Claim · model-written summary
At recommended nitrogen, elevated carbon dioxide did not affect corn production.
- Taxon
- Corn
Zea mays subsp. mayst0 - Treatment
- carbon dioxidee0
- Outcome
- productione0
- Direction
- no carbon dioxide effecte0
- Qualifier
- recommended rate of nitrogen applicatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the recommended rate of nitrogen application, no carbon dioxide effect on production occurred.”
t0“Corn”
Claim · model-written summary
Elevated carbon dioxide reduced ear biomass below the recommended nitrogen rate and increased it at the highest rates.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- elevated carbon dioxide treatmente0
- Outcome
- eare0
- Direction
- lowere0
- Qualifier
- less than the recommended rate of nitrogen applicatione0
- Comparator
- ambient treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Corn”
Claim · model-written summary
Elevated carbon dioxide reduced leaf plus stem biomass below recommended nitrogen and increased it at highest rates.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- elevated carbon dioxide treatmente0
- Outcome
- leaf plus stem biomasse0
- Direction
- lowere0
- Qualifier
- less than the recommended rate of nitrogen applicatione0
- Comparator
- ambient treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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.”
t0“Corn”
Claim · model-written summary
Mid-day leaf gas exchange did not respond significantly to nitrogen rate under either carbon dioxide treatment.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- nitrogen application ratee0
- Outcome
- mid-day leaf gas exchange ratese0
- Direction
- no significant responsese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no significant responses of mid-day leaf gas exchange rates to nitrogen application rate for either carbon dioxide treatment”
t0“Corn”
Claim · model-written summary
Elevated carbon dioxide did not significantly increase leaf carbon dioxide assimilation at any nitrogen level.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- elevated carbon dioxidee0
- Outcome
- leaf carbon dioxide assimilation ratese0
- Direction
- did not significantly increasee0
- Qualifier
- at any nitrogen levele0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated carbon dioxide did not significantly increase leaf carbon dioxide assimilation rates at any nitrogen level”
t0“Corn”
Claim · model-written summary
Vegetative leaf area index increased more with nitrogen at elevated than ambient carbon dioxide.
- Taxon
- CornZea mays subsp. mayst0
- Organ / stage
- vegetative growthe0
- Treatment
- nitrogen application ratee0
- Outcome
- Leaf area indexe0
- Direction
- increased moree0
- Comparator
- ambient carbon dioxidee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area index during vegetative growth increased more with nitrogen application rate at elevated than at ambient carbon dioxide.”
t0“Corn”
Claim · model-written summary
Elevated carbon dioxide increased corn growth responsiveness to nitrogen through leaf area response.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- elevated carbon dioxidee0
- Outcome
- responsiveness of corn growth to nitrogen applicatione0
- Direction
- increasede0
- Qualifier
- by increasing the response of leaf area to nitrogen application ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated carbon dioxide increased the responsiveness of corn growth to nitrogen application by increasing the response of leaf area to nitrogen application rate”
Claim · model-written summary
Elevated carbon dioxide increased nitrogen required for maximum corn yields.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- elevated carbon dioxidee0
- Outcome
- amount of nitrogen required to achieve maximum yieldse0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated carbon dioxide increased the amount of nitrogen required to achieve maximum yields”
t0“Corn”
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