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Physiological effects of long term exposure to low concentrations of SO2 and NH3 on poplar leaves 总被引:1,自引:0,他引:1
L. W. A. van Hove O. van Kooten K. J. van Wijk W. J. Vredenberg E. H. Adema G. A. Pieters 《Physiologia plantarum》1991,82(1):32-40
Shoots of poplar (Populus euramericana L. cv. Flevo) were exposed to filtered air, SO2, NH3 or a mixture of SO2 and NH3 for 7 weeks in fumigation chambers. After this exposure gas exchange measurements were carried out using a leaf chamber. As compared to leaves exposed to filtered air, leaves pretreated with 112 μg m?3 SO2 showed a small reduction in maximum CO2 assimilation rate (Pmax) and stomatal conductance (gs). They also showed a slightly higher quantum yield and dark respiration. In addition, the fluorescence measurements indicated that the Calvin cycle of the leaves pretreated with 112 μg m?3 SO2 was more rapidly activated after transition from dark to light. An exposure to 64 μg m?3 NH3 had a positive effect on Pmax, stomatal conductance and NH3 uptake of the leaves. This positive effect was counteracted by an SO2 concentration of 45 μg m?3. The exposure treatments appeared to have no effect on the relationship between net CO2-assimilation and gs. Also, no injury of the leaf cuticle or of epidermal cells was observed. Resistance analysis showed that NH3 transfer into the leaf can be estimated from data on the boundary layer and stomatal resistance for H2O transfer and NH3 concentration at the leaf surface, irrespective of whether the leaves are exposed for a short or long time to NH3 or to a mixture of NH3 and SO2. In contrast SO2 uptake into the leaves was only partly correlated to the stomatal resistance. The results suggest a large additional uptake of this gas by the leaves. The possibility of a difference in path length between SO2 and H2O molecules is proposed. 相似文献
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Physiological effects of five months exposure to low concentrations of O3 and NH3 on Douglas fir (Pseudotsuga menziesii) 总被引:2,自引:0,他引:2
Three years old seedlings of Douglas fir (Pseudotsuga menziesii) were exposed lo filtered air, O3 (day and night concentrations of 78 and 30 μgm?3: respectively). NH3 (54 μg m?3) and to a mixture of NH3+O3 (day and night concentrations of 49 + 83 and 49 + 44 μg m?3 respectively), for 5 months in fumigation chambers. Both gas exchange and chlorophyll fluorescence were measured on shoots which had sprouted at the beginning of the exposure period. After 4. 8, 10 and 20 weeks of exposure, light response curves of electron transport rate (J) were determined, in which J was deduced from chlorophyll fluorescence. Net CO2 assimiialion was measured at maximum light intensity of 560) μmol m?2 S?1 (Pn.560). After 8 and 10 weeks of exposure also light response curves of CO2 assimilation were assessed. Shoots exposed to O3 showed a reduction in net CO2 assimilation as compared to the control shoots during the entire exposure period. The reduction was related lo a lower chlorophyll content and a lower electron transport rate, whereas no effect on quantum yield efficiency (qy) was observed. In contrast, shoots exposed to NH3 showed a positive effect on photosynthesis. Shoots exposed to NH3. + O3 showed a rapid increase in Pn.560, in the period between 4 and 8 weeks to a level equal of that of the NH3-treatment. After this period a decline in Pn.560 was observed. After 10 weeks of exposure shoots exposed to O3 showed an increased transpiration rate in the dark as compared to the control shoots. In addition, water use efficiency (WUE) declined as a result of an increase in leaf conductance. Both observations indicate that the stomatal apparatus was affected by O3. A high transpiration rate in the dark was also found for shoots esposed to NHX. However, shoots exposed to NH3+ O3 showed neither an effect on WUE, nor an effect on transpiration rate in the dark. The possibility that NH3 delayed the O3 induced effects on photosynthesis and stomatal conductance is discussed. 相似文献
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Physiological effects of a long term exposure to low concentrations of NH3 , NO2 and SO2 on Douglas fir (Pseudotsuga menziesii) 总被引:1,自引:0,他引:1
L. W. A. van Hove M. E. Bossen M. G. J. Mensink O. van Kooten 《Physiologia plantarum》1992,86(4):559-567
The above-ground parts of two years old seedlings of Douglas fir (Pseudotsuga menziesii) were exposed to filtered air, NH3, NO2+, SO2 (66, 96 and 95 μg m?3, respectively), to a mixture of NO2+NH3 (55 + 82 μg m?3) or SO2+NO2 (128 + 129 μg m?3), for 8 months in fumigation chambers. Both chlorophyll fluorescence and gas exchange measurements were carried out on shoots which had sprouted at the beginning of the exposure period. The chlorophyll fluorescence measurements were performed after 3 and 5 months of exposure (average shoot age 70 and 140 days, respectively). Light response curves of electron transport rate (J) were determined, in which J was deduced from chlorophyll fluorescence. In addition, light response curves of net CO2 assimilation were determined after 5 months of exposure. After 3 months of exposure (average shoot age 70 days) all exposure treatments showed a lower maximum electron transport rate (Jmax) as compared to the control shoots (filtered air). A large reduction (45%) was observed for shoots exposed to SO2+NO2. During the exposure period between 3 and 5 months (average shoot age 70 and 140 days, respectively) a decrease of Jmax was observed for all treatments. Jmax had further declined some time after termination of the exposure, when average shoot age was 310 days. Shoots exposed to SO2 and SO2+NO2 also showed a reduction in maximum net CO2 assimilation (Pmax) as compared to the control shoots. However, shoots exposed to NO2 showed no reduction and even a higher Pmax was observed for shoots exposed to NH3 or NO2+NH3. Needles of these treatments also showed a higher chlorophyll content which might explain the contradictory results obtained for these treatments: the increased amount of photosynthetic units counteracts the reduction in Jmax and consequently no reduction in Pmax is measured. Shoots exposed to SO2 and SO2+NO2 also showed a reduction in maximum stomatal conductance (gs). However, the stomatal opening was larger than could be expected on basis of their (maximum) CO2 assimilation rate. Consequently, water use efficiency of these shoots was lower than that of the control shoots. Also shoots exposed to NO2 had a lower water use efficiency due to a significantly higher maximum gs. Shoots exposed to NH3 showed a high transpiration rate in the dark, indicating imperfect stomatal closure. 相似文献
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Delayed NH3 and N2 O uptake by maize leaves 总被引:1,自引:1,他引:0
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Effects of low level O3 exposure on leaf diffusive conductance and water-use efficiency in hybrid poplar 总被引:10,自引:2,他引:8
Abstract Young, amphistomatous hybrid poplar (Populus deltoides x trichocarpa) plants were exposed daily to either background (0.025 cm3 m-3) or elevated (0.125 cm3 m-3) concentrations of O3. Levels of abaxial and adaxial leaf conductance were affected interactively by pollutant treatment, leaf age, and photon fluence rate. Consequently, conductance in O3-treated leaves was sometimes higher and sometimes lower than in comparable control leaves, depending on leaf age or level of photon fluence rate. For example, at low photon fluence rate or in the dark, conductance was greater in O3-treated than in control plants, while at high photon fluence rate that relationship was reversed. Exposure to O3 also reduced the water-use efficiency and range of leaf conductance of individual leaves, and altered the relationship between the conductances of the two leaf surfaces (the ratio of abaxial to adaxial leaf conductance was increased). Furthermore, O3 treatment resulted in diminished stomatal control of water loss; excised O3-treated leaves had higher conductances and wilted sooner than excised control leaves of identical ages. Overall, the data indicate that exposure to O3 resulted in impaired stomatal function. 相似文献
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Stomatal sensitivity to vapour pressure difference over a subambient to elevated CO2 gradient in a C3 /C4 grassland 总被引:1,自引:0,他引:1
In the present study the response of stomatal conductance (gs) to increasing leaf‐to‐air vapour pressure difference (D) in early season C3 (Bromus japonicus) and late season C4 (Bothriochloa ischaemum) grasses grown in the field across a range of CO2 (200–550 µmol mol?1) was examined. Stomatal sensitivity to D was calculated as the slope of the response of gs to the natural log of externally manipulated D (dgs/dlnD). Increasing D and CO2 significantly reduced gs in both species. Increasing CO2 caused a significant decrease in stomatal sensitivity to D in Br. japonicus, but not in Bo. ischaemum. The decrease in stomatal sensitivity to D at high CO2 for Br. japonicus fit theoretical expectations of a hydraulic model of stomatal regulation, in which gs varies to maintain constant transpiration and leaf water potential. The weaker stomatal sensitivity to D in Bo. ischaemum suggested that stomatal regulation of leaf water potential was poor in this species, or that non‐hydraulic signals influenced guard cell behaviour. Photosynthesis (A) declined with increasing D in both species, but analyses of the ratio of intercellular to atmospheric CO2 (Ci/Ca) suggested that stomatal limitation of A occurred only in Br. japonicus. Rising CO2 had the greatest effect on gs and A in Br. japonicus at low D. In contrast, the strength of stomatal and photosynthetic responses to CO2 were not affected by D in Bo. ischaemum. Carbon and water dynamics in this grassland are dominated by a seasonal transition from C3 to C4 photosynthesis. Interspecific variation in the response of gs to D therefore has implications for predicting seasonal ecosystem responses to CO2. 相似文献
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A. Noormets A. Sôber E. J. Pell R. E. Dickson G. K. Podila J. Sôber J. G. Isebrands & D. F. Karnosky 《Plant, cell & environment》2001,24(3):327-336
Leaf gas exchange parameters and the content of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) in the leaves of two 2‐year‐old aspen (Populus tremuloides Michx.) clones (no. 216, ozone tolerant and no. 259, ozone sensitive) were determined to estimate the relative stomatal and mesophyll limitations to photosynthesis and to determine how these limitations were altered by exposure to elevated CO2 and/or O3. The plants were exposed either to ambient air (control), elevated CO2 (560 p.p.m.) elevated O3 (55 p.p.b.) or a mixture of elevated CO2 and O3 in a free air CO2 enrichment (FACE) facility located near Rhinelander, Wisconsin, USA. Light‐saturated photosynthesis and stomatal conductance were measured in all leaves of the current terminal and of two lateral branches (one from the upper and one from the lower canopy) to detect possible age‐related variation in relative stomatal limitation (leaf age is described as a function of leaf plastochron index). Photosynthesis was increased by elevated CO2 and decreased by O3 at both control and elevated CO2. The relative stomatal limitation to photosynthesis (ls) was in both clones about 10% under control and elevated O3. Exposure to elevated CO2 + O3 in both clones and to elevated CO2 in clone 259, decreased ls even further – to about 5%. The corresponding changes in Rubisco content and the stability of Ci/Ca ratio suggest that the changes in photosynthesis in response to elevated CO2 and O3 were primarily triggered by altered mesophyll processes in the two aspen clones of contrasting O3 tolerance. The changes in stomatal conductance seem to be a secondary response, maintaining stable Ci under the given treatment, that indicates close coupling between stomatal and mesophyll processes. 相似文献
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A combined model to simulate CO2 and H2O gas exchange at the leaf scale was parameterized using data obtained from in situ leaf‐scale observations of diurnal and seasonal changes in the CO2 and H2O gas exchange of four temperate deciduous broad‐leaved trees using a porometric method. The model consists of a Ball et al. type stomatal conductance submodel [Ball, Woodrow & Berry, pp. 221–224 in Progress in Photosynthesis Research (ed. I. Biggins), Martinus‐Nijhoff Publishers, Dordrecht, The Netherlands, 1987] and a Farquhar et al. type biochemical submodel of photosynthesis (Farquhar, von Caemmerer & Berry, Planta 149, 78–90, 1980). In these submodels, several parameters were optimized for each tree species as representative of the quantitative characteristics related to gas exchange. The results show that the seasonal physiological changes of Vcmax25 in the biochemical model of photosynthesis should be used to estimate the long‐term CO2 gas exchange. For Rd25 in the biochemical model of photosynthesis and m in the Ball et al. type stomatal conductance model, the difference should be counted during the leaf expansion period. 相似文献
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Elevated atmospheric CO2 improved Sorghum plant water status by ameliorating the adverse effects of drought 总被引:2,自引:0,他引:2
G. W. Wall T. J. Brooks N. R. Adam A. B. Cousins B. A. Kimball P. J. Pinter Jr R. L. LaMorte J. Triggs M. J. Ottman S. W. Leavitt A. D. Matthias D. G. Williams A. N. Webber 《The New phytologist》2001,152(2):231-248
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Stomatal conductance of forest species after long-term exposure to elevated CO2 concentration: a synthesis 总被引:13,自引:4,他引:9
B. E. Medlyn C. V. M. Barton M. S. J. Broadmeadow R. Ceulemans P. De Angelis M. Forstreuter M. Freeman S. B. Jackson S. Kellomäki E. Laitat A. Rey P. Roberntz B. D. Sigurdsson J. Strassemeyer K. Wang P. S. Curtis P. G. Jarvis 《The New phytologist》2001,149(2):247-264
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Leaf growth of hybrid poplar following exposure to elevated CO2 总被引:1,自引:1,他引:0
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Elevated atmospheric CO2 alters stomatal responses to variable sunlight in a C4 grass 总被引:1,自引:1,他引:0
Native tallgrass prairie in NE Kansas was exposed to elevated (twice ambient) or ambient atmospheric CO2 levels in open-top chambers. Within chambers or in adjacent unchambered plots, the dominant C4 grass, Andropogon gerardii, was subjected to fluctuations in sunlight similar to that produced by clouds or within canopy shading (full sun > 1500 μmol m−2 s−1 versus 350 μmol m−2 s−1 shade) and responses in gas exchange were measured. These field experiments demonstrated that stomatal conductance in A. gerardii achieved new steady state levels more rapidly after abrupt changes in sunlight at elevated CO2 when compared to plants at ambient CO2. This was due primarily to the 50% reduction in stomatal conductance at elevated CO2, but was also a result of more rapid stomatal responses. Time constants describing stomatal responses were significantly reduced (29–33%) at elevated CO2. As a result, water loss was decreased by as much as 57% (6.5% due to more rapid stomatal responses). Concurrent increases in leaf xylem pressure potential during periods of sunlight variability provided additional evidence that more rapid stomatal responses at elevated CO2 enhanced plant water status. CO2-induced alterations in the kinetics of stomatal responses to variable sunlight will likely enhance direct effects of elevated CO2 on plant water relations in all ecosystems. 相似文献
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