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Energy requirement for symbiotic nitrogen fixation.
1Department of Agronomy, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia.
Nature
|May 12, 1977
Summary
Legumes
Area of Science:
- Plant physiology
- Biochemistry
- Agricultural science
Background:
- Nitrogen is essential for plant growth.
- Legumes can fix atmospheric nitrogen symbiotically.
- Nitrogen can also be assimilated from soil nitrates.
Purpose of the Study:
- To compare the energy costs of symbiotic nitrogen fixation versus nitrate assimilation in legumes.
- To test the hypothesis that symbiotic nitrogen fixation and nitrate assimilation have similar energy costs.
Main Methods:
- Utilized a modified McCree method.
- Investigated CO2 efflux in Trifolium subterraneum L. (subterranean clover).
- Partitioned dark CO2 efflux into synthesis and maintenance components.
Main Results:
- Symbiotic nitrogen fixation and nitrate assimilation require comparable energy.
- Approximately 15% of net photosynthetic production is allocated to nitrogen requirements.
- Nitrogen fixation and assimilation contribute to the CO2 flux associated with synthesis.
Conclusions:
- The energy cost of symbiotic nitrogen fixation is similar to nitrate assimilation.
- Legumes utilizing symbiotic nitrogen fixation exhibit similar growth coefficients to those using mineral nitrogen.
- This supports the hypothesis of equivalent energy costs for different nitrogen acquisition strategies.
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