Record Display for the EPA National Library CatalogRECORD NUMBER: 21 OF 288
|Main Title||Analysis of the Relationships among O3 Uptake, Conductance, and Photosynthesis in Needles of 'Pinus ponderosa'.|
|Author||Weber, J. A. ; Clark, C. S. ; Hogsett, W. E. ;|
|CORP Author||Corvallis Environmental Research Lab., OR. ;ManTech Environmental Technology, Inc., Corvallis, OR.|
|Additional Subjects||Ozone ; Pine trees ; Exposure ; Air pollution control ; Air pollution effects(Plants) ; Photosynthesis ; Exhaust gases ; Resistance ; Concentration(Composition) ; Response ; Tolerances(Physiology) ; Air filters ; Recovery ; Photons ; Charcoal ; Statistical analysis ; Regression analysis ; Diurnal variations ; Tables(Data) ; Reprints ; Cumulative uptake ; Stomata limitation ; Pinus ponderosa ; Ponderosa pine trees|
The determination of conductance and photosynthesis to ozone uptake is important for the prediction of the long-term response of trees to ozone exposure. The authors studied the effects of O3 uptake on conductance (gwv) and photosynthesis (A) in needles of ponderosa pine (Pinus ponderosa) seedlings exposed for 70 days to one of three O3 regimes -- Low-O3, High-O3, and Low/High-O3. Seedlings exposed to charcoal-filtered air served as controls. Total O3 exposures, expressed as ppm-h (the sum of the average hourly concentration to ppm over the exposure period), were 77, 135, 105, and 4 for the Low-O3, High-O3, Low/High-O3, and control treatments, respectively. Conductance declined to about 60% of the value in control seedlings by Day 6 in seedlings in the High-O3 treatment and by Day 37 in seedlings in the Low/High-O3 treatment, but did not decline at all in seedlings in the Low-O3 treatment.