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Quantifying foliar uptake of gaseous nitrogen dioxide using enriched foliar delta15N values
Dena M Vallano1, Jed P Sparks1
1Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853-2701, USA.
The New Phytologist
|December 12, 2007
Summary
Plants can absorb nitrogen dioxide (NO(2)) directly through their leaves, contributing to their nitrogen needs, especially under nutrient-poor conditions. This foliar uptake of nitrogen dioxide does not significantly impact growth at typical environmental concentrations.
Area of Science:
- Plant Physiology
- Environmental Science
- Biogeochemistry
Background:
- Gaseous nitrogen dioxide (NO(2)) is a common air pollutant with potential impacts on plant life.
- Understanding direct foliar uptake of NO(2) is crucial for assessing its role in plant nitrogen nutrition.
- Nitrogen isotopic composition (delta(15)N) offers a method to trace nitrogen assimilation pathways in plants.
Purpose of the Study:
- To quantify the direct uptake of gaseous nitrogen dioxide (NO(2)) into tomato and tobacco leaves.
- To determine the impact of foliar NO(2) uptake on plant metabolism and growth.
- To assess the utility of foliar nitrogen isotopic composition (delta(15)N) for tracing NO(2) assimilation.
Main Methods:
- A hydroponics-fumigation system was employed to expose plant shoots to isotopically labeled (15)NO(2) and roots to varying nitrate concentrations.
- Morphological, stable isotope (delta(15)N and delta(13)C), and nitrate reductase activity (NRA) analyses were conducted.
- Quantification of (15)N incorporation into plant biomass was performed.
Main Results:
- Tomato (Lycopersicon esculentum) and tobacco (Nicotiana tabacum) incorporated 11% and 15% of supplied (15)NO(2)-N into biomass, respectively, via foliar uptake.
- Plant biomass accumulation, allocation, carbon isotope composition (delta(13)C), and nitrate reductase activity (NRA) showed no significant response to NO(2) exposure at 40 ppb.
- Significant amounts of nitrogen from NO(2) were assimilated into plant tissues, irrespective of external nitrogen availability.
Conclusions:
- Foliar uptake of nitrogen dioxide (NO(2)) can be a significant source of nitrogen for plants, particularly under nitrogen-limited conditions.
- At concentrations up to 40 ppb, direct NO(2) uptake does not substantially affect plant growth or metabolism.
- Foliar delta(15)N analysis is a viable method for tracing the contribution of gaseous NO(2) to plant nitrogen nutrition.
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