Physiological mechanisms influencing plant nitrogen isotope composition
1University of Arkansas Stable Isotope Laboratory, Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA. devans@uark.edu
Trends in Plant Science
|March 10, 2001
Summary
Plant nitrogen isotope composition reflects external nitrogen sources, but internal plant processes and mycorrhizae can alter this signal. Understanding these variations is key for plant nitrogen uptake research.
Area of Science:
- Plant Physiology
- Stable Isotope Ecology
- Biogeochemistry
Background:
- Nitrogen isotope composition (δ15N) in plants is influenced by the nitrogen source and internal plant physiology.
- Whole-plant δ15N can mirror the external nitrogen source when plant nitrogen demand outpaces supply.
Purpose of the Study:
- To elucidate the factors controlling whole-plant and leaf nitrogen isotope composition in plants.
- To identify mechanisms causing deviations from the external nitrogen source signature within plants.
Main Methods:
- Analysis of whole-plant and leaf nitrogen isotope ratios.
- Comparison of plant δ15N with external nitrogen source isotope ratios.
- Consideration of physiological processes like nitrogen uptake, assimilation, and reallocation.
Main Results:
- Plant nitrogen isotope composition is a function of both the external nitrogen source and internal plant physiological mechanisms.
- Mycorrhizal uptake can lead to a divergence between plant and source δ15N.
- Intra-plant δ15N variation arises from multiple assimilation events, organ-specific nitrogen loss, and nitrogen resorption/reallocation.
Conclusions:
- Plant nitrogen isotope composition provides insights into nitrogen source and plant physiological status.
- Further research is needed on organic nitrogen acquisition, mycorrhizal roles, and internal nitrogen transformations.
- Understanding these factors is crucial for accurately interpreting plant δ15N as an ecological tracer.
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