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Global aspects of C/N interactions determining plant-environment interactions
John A Raven1, Linda L Handley, Mitchell Andrews
1Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee, Dundee DD1 4HN, UK. j.a.raven@dundee.ac.uk
Journal of Experimental Botany
|December 3, 2003
Summary
The atomic carbon-to-nitrogen (C:N) ratio varies significantly across photolithotrophs, impacting nitrogen assimilation. Organisms with higher C:N ratios, like terrestrial plants, have different nutrient needs and growth costs compared to aquatic species.
Area of Science:
- Biogeochemistry
- Plant Physiology
- Microbial Ecology
Background:
- The atomic carbon-to-nitrogen (C:N) ratio in photolithotrophs is determined by their biochemical composition, ranging from 5 in microalgae to higher values in macroalgae and plants.
- Differences in C:N ratios influence nitrogen assimilation rates between marine and terrestrial environments, despite similar global carbon assimilation.
- Aquatic organisms utilize dissolved inorganic carbon and nitrogen, while terrestrial photolithotrophs obtain carbon and nitrogen from the atmosphere and soil.
Purpose of the Study:
- To explore the implications of varying C:N ratios in photolithotrophs on nutrient assimilation and growth.
- To investigate the factors influencing nitrogen and water costs of growth in terrestrial plants.
- To understand the role of C:N ratios in regulating terrestrial-to-aquatic nutrient fluxes.
Main Methods:
- Comparative analysis of C:N ratios across different photolithotroph groups.
- Examination of nutrient acquisition strategies in aquatic versus terrestrial environments.
- Modeling of nitrogen and water costs associated with plant growth based on C:N ratios and resource availability.
Main Results:
- Significant variations in C:N ratios exist, affecting nitrogen assimilation patterns globally.
- Terrestrial plants can adjust their C:N ratios with minimal impact on growth by altering solute composition or protein content.
- Lower water costs for terrestrial plants are observed with increased nitrogen and carbon availability, influencing denitrification and nutrient fluxes.
Conclusions:
- The C:N ratio is a critical factor governing nutrient dynamics and growth efficiency in photolithotrophs.
- Understanding C:N variations is essential for predicting ecosystem responses to environmental changes and nutrient availability.
- Plant physiological adjustments and environmental factors like water and nutrient supply interact to shape biogeochemical cycles.