Photosynthesis and Respiration of Developing Populus tremuloides Internodes
1Department of Environmental and Forest Biology, State University of New York, Syracuse, New York 13210.
Plant Physiology
|April 1, 1982
Summary
Populus tremuloides internodes show declining photosynthesis as bark develops. Stem respiration consistently exceeds photosynthesis, increasing with temperature up to 50°C.
Area of Science:
- Plant Physiology
- Forest Ecology
- Wood Biology
Background:
- Developing tree internodes undergo significant anatomical and morphological changes.
- Metabolic activity, including photosynthesis and respiration, shifts during internode development.
- Understanding these metabolic shifts is crucial for forest productivity and carbon cycling.
Purpose of the Study:
- To evaluate the photosynthetic and respiratory performance of developing Populus tremuloides internodes.
- To correlate anatomical and morphological transitions with metabolic activity.
- To determine the impact of temperature on stem photosynthesis and respiration.
Main Methods:
- Infrared gas analysis was used to measure gas exchange.
- Photosynthetic rates were quantified in developing internodes.
- Respiration rates were measured across a range of temperatures.
Main Results:
- Photosynthetic rates decreased from 6.0-10.0 mg CO2 dm-2 hr-1 in young internodes to 2.5-3.8 mg CO2 dm-2 hr-1 in mature internodes.
- Stem respiration exceeded photosynthesis by approximately a factor of two on average.
- Stem photosynthesis increased with temperature up to 40°C, declining sharply thereafter, while respiration rose linearly up to 50°C.
Conclusions:
- Internode development in Populus tremuloides involves a transition from net carbon gain to a net carbon loss state.
- Stem respiration is a significant metabolic process in these internodes, highly sensitive to temperature.
- These findings have implications for understanding carbon allocation and energy balance in trees.
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