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1.
To determine how increased atmospheric CO2 will affect the physiology of coppiced plants, sprouts originating from two hybrid poplar clones ( Populus trichocarpa × P. deltoides - Beaupre and P. deltoides × P. nigra - Robusta) were grown in open-top chambers containing ambient or elevated (ambient + 360 μmol mol−1 ) CO2 concentration. The effects of elevated CO2 concentration on leaf photosynthesis, stomatal conductance, dark respiration, carbohydrate concentration and nitrogen concentration were measured. Furthermore, dark respiration of leaves was partitioned into growth and maintenance components by regressing specific respiration rate vs specific growth rate. Sprouts of both clones exposed to CO2 enrichment showed no indication of photosynthetic down-regulation. During reciprocal gas exchange measurements, CO2 enrichment significantly increased photosynthesis of all sprouts by approximately 60% ( P < 0.01) on both an early and late season sampling date, decreased stomatal conductance of all sprouts by 10% ( P < 0.04) on the early sampling date and nonsignificantly decreased dark respiration by an average of 11%. Growth under elevated CO2 had no consistent effect on foliar sugar concentration but significantly increased foliar starch by 80%. Respiration rate was highly correlated with both specific growth rate and percent nitrogen. Long-term CO2 enrichment did not significantly affect the maintenance respiration coefficient or the growth respiration coefficient. Carbon dioxide enrichment affected the physiology of the sprouts the same way it affected these plants before they were coppiced. 相似文献
2.
To investigate the diurnal variation of stomatal sensitivity to CO2 , stomatal response to a 30 min pulse of low CO2 was measured four times during a 24 h time-course in two Crassulacean acid metabolism (CAM) species Kalanchoe daigremontiana and Kalanchoe pinnata , which vary in the degree of succulence, and hence, expression and commitment to CAM. In both species, stomata opened in response to a reduction in p CO2 in the dark and in the latter half of the light period, and thus in CAM species, chloroplast photosynthesis is not required for the stomatal response to low p CO2 . Stomata did not respond to a decreased p CO2 in K. daigremontiana in the light when stomata were closed, even when the supply of internal CO2 was experimentally reduced. We conclude that stomatal closure during phase III is not solely mediated by high internal p CO2 , and suggest that in CAM species the diurnal variability in the responsiveness of stomata to p CO2 could be explained by hypothesizing the existence of a single CO2 sensor which interacts with other signalling pathways. When not perturbed by low p CO2 , CO2 assimilation rate and stomatal conductance were correlated both in the light and in the dark in both species. 相似文献
3.
Interaction of elevated CO2 and O3 on growth, photosynthesis and respiration of three perennial species grown in low and high nitrogen 总被引:1,自引:0,他引:1
Seedlings of three species native to central North America, a C3 tree, Populus tremuloides Michx., a C3 grass, Agropyron smithii Rybd., and a C4 grass, Bouteloua curtipendula Michx., were grown in all eight combinations of two levels each of CO2 , O3 and nitrogen (N) for 58 days in a controlled environment. Treatment levels consisted of 360 or 674 μmol mol-1 CO2 , 3 or 92 nmol mol-1 O3 , and 0.5 or 6.0 m M N. In situ photosynthesis and relative growth rate (RGR) and its determinants were obtained at each of three sequential harvests, and leaf dark respiration was measured at the second and third harvests. In all three species, plants grown in high N had significantly greater whole-plant mass, RGR and photosynthesis than plants grown in low N. Within a N treatment, elevated CO2 did not significantly enhance any of these parameters nor did it affect leaf respiration. However, plants of all three species grown in elevated CO2 had lower stomatal conductance compared to ambient CO2 -exposed plants. Seedlings of P. tremuloides (in both N treatments) and B. curtipendula (in high N) had significant ozone-induced reductions in whole-plant mass and RGR in ambient but not under elevated CO2. This negative O3 impact on RGR in ambient CO2 was related to increased leaf dark respiration, decreased photosynthesis and/or decreased leaf area ratio, none of which were noted in high O3 treatments in the elevated CO2 environment. In contrast, A. smithii was marginally negatively affected by high O3. 相似文献
4.
Changes in leaf nitrogen and carbohydrates underlie temperature and CO2 acclimation of dark respiration in five boreal tree species 总被引:8,自引:3,他引:5
We tested the hypothesis that acclimation of foliar dark respiration to CO2 concentration and temperature is associated with adjustments in leaf structure and chemistry. Populus tremuloides Michx. , Betula papyrifera Marsh. , Larix laricina (Du Roi) K. Koch , Pinus banksiana Lamb., and Picea mariana (Mill.) B.S.P. were grown from seed in combined CO2 (370 or 580 μ mol mol–1 ) and temperature treatments (18/12, 24/18, or 30/24 °C). Temperature and CO2 effects were predominately independent. Specific respiration rates partially acclimated to warmer thermal environments through downward adjustment in the intercept, but not Q 10 of the temperature–response functions. Temperature acclimation of respiration was larger for conifers than broad-leaved species and was associated with pronounced reductions in leaf nitrogen concentrations in conifers at higher growth temperatures. Short-term increases in CO2 concentration did not inhibit respiration. Growth in the elevated CO2 concentration reduced leaf nitrogen and increased non-structural carbohydrate concentrations. However, for a given nitrogen concentration, respiration was higher in leaves grown in the elevated CO2 concentration, as rates increased with increasing carbohydrates. Across species and treatments, respiration rates were a function of both leaf nitrogen and carbohydrate concentrations ( R 2 = 0·71, P < 0·0001). Long-term acclimation of foliar dark respiration to temperature and CO2 concentration is largely associated with changes in nitrogen and carbohydrate concentrations. 相似文献
5.
Effect of elevated CO2 on the stomatal distribution and leaf physiology of Alnus glutinosa 总被引:1,自引:1,他引:0
Variation in stomatal development and physiology of mature leaves from Alnus glutinosa plants grown under reference (current ambient, 360 μmol mol−1 CO2 ) and double ambient (720 μmol mol−1 CO2 ) carbon dioxide (CO2 ) mole fractions is assessed in terms of relative plant growth, stomatal characters (i.e. stomatal index and density) and leaf photosynthetic characters. This is the first study to consider the effects of elevated CO2 concentration on the distribution of stomata and epidermal cells across the whole leaf and to try to ascertain the cause of intraleaf variation. In general, a doubling of the atmospheric CO2 concentration enhanced plant growth and significantly increased stomatal index. However, there was no significant change in relative stomatal density. Under elevated CO2 concentration there was a significant decrease in stomatal conductance and an increase in assimilation rate. However, no significant differences were found for the maximum rate of carboxylation ( V cmax ) and the light saturated rate of electron transport ( J max ) between the control and elevated CO2 treatment. 相似文献
6.
We developed and applied an ecosystem-scale model that calculated leaf CO2 assimilation, stomatal conductance, chloroplast CO2 concentration and the carbon isotope composition of carbohydrate formed during photosynthesis separately for sunlit and shaded leaves within multiple canopy layers. The ecosystem photosynthesis model was validated by comparison to leaf-level gas exchange measurements and estimates of ecosystem-scale photosynthesis from eddy covariance measurements made in a coastal Douglas-fir forest on Vancouver Island. A good agreement was also observed between modelled and measured δ 13 C values of ecosystem-respired CO2 ( δ R ). The modelled δ R values showed strong responses to variation in photosynthetic photon flux density (PPFD), air temperature, vapour pressure deficit (VPD) and available soil moisture in a manner consistent with leaf-level studies of photosynthetic 13 C discrimination. Sensitivity tests were conducted to evaluate the effect of (1) changes in the lag between the time of CO2 fixation and the conversion of organic matter back to CO2 ; (2) shifts in the proportion of autotrophic and heterotrophic respiration; (3) isotope fractionation during respiration; and (4) environmentally induced changes in mesophyll conductance, on modelled δ R values. Our results indicated that δ R is a good proxy for canopy-level C c / C a and 13 C discrimination during photosynthetic gas exchange, and therefore has several applications in ecosystem physiology. 相似文献
7.
The mechanisms mediating CO2 sensing and light–CO2 interactions in guard cells are unknown. In growth chamber-grown Vicia faba leaves kept under constant light (500 μ mol m–2 s–1 ) and temperature, guard cell zeaxanthin content tracked ambient [CO2 ] and stomatal apertures. Increases in [CO2 ] from 400 to 1200 cm3 m–3 decreased zeaxanthin content from 180 to 80 mmol mol–1 Chl and decreased stomatal apertures by 7·0 μ m. Changes in zeaxanthin and aperture were reversed when [CO2 ] was lowered. Guard cell zeaxanthin content was linearly correlated with stomatal apertures. In the dark, the CO2 -induced changes in stomatal aperture were much smaller, and guard cell zeaxanthin content did not change with chamber [CO2 ]. Guard cell zeaxanthin also tracked [CO2 ] and stomatal aperture in illuminated stomata from epidermal peels. Dithiothreitol (DTT), an inhibitor of zeaxanthin formation, eliminated CO2 -induced zeaxanthin changes in guard cells from illuminated epidermal peels and reduced the stomatal CO2 response to the level observed in the dark. These data suggest that CO2 -dependent changes in the zeaxanthin content of guard cells could modulate CO2 -dependent changes of stomatal apertures in the light while a zeaxanthin-independent CO2 sensing mechanism would modulate the CO2 response in the dark. 相似文献
8.
Spruce seedlings [ Picea abies (L.) Karst.] were exposed to a range of concentrations of Zn, Cd, Hg and methyl-Hg for 5 weeks. The chlorophyll and water content of the needles were then estimated. The rates of photosynthesis, transpiration and dark respiration of the intact plant were determined using a Li-cor portable photosynthesis measuring system. Chlorophyll and water contents of needles decreased in response to all metal treatments, as did CO2 uptake. At 1 μ M Cd, 0.1 μ M Hg and 30 and 60 μ M Zn, the decrease in CO2 uptake could be accounted for by decreased chlorophyll concentrations. Decreased transpiration was only found at 5 μ M Cd and 0.01 μ M methyl-Hg. At 5 μ M Cd most of the decrease in CO2 uptake could be explained by decreased chlorophyll levels and stomatal closure induced by water stress. At 0.01 μ M methyl-Hg, besides a decrease in chlorophyll concentration and partial stomatal closure, photosynthetic reactions may have been directly affected. Respiration rates were not influenced by exposure to heavy metals. 相似文献
9.
Definitions of the variables used and the units are given in Table 1
The literature reports enormous variation between species in the extent of stomatal responses to rising CO
Table 1 . Abbreviations 相似文献
10.
Respiration measured as CO2 efflux was determined at various soil O2 and CO2 concentrations for individual, attached roots of a succulent perennial from the Sonoran Desert, Agave deserti Engelm. The respiration rate increased with increasing O2 concentration up to about 16% O2 for established roots and 5% O2 for rain roots (fine branch roots on established roots induced by wetting of the soil) and then remained fairly constant up to 21% O2 . When O2 was decreased from 21 to 0%, the respiration rates were similar to those obtained with increasing O2 concentration. The CO2 concentration in the root zone, which for the shallow-rooted A. deserti in the field was about 1 000 μl l-1 , did not affect root respiration at concentrations up to 2 000 μl l-1 , but higher concentrations reduced it, respiration being abolished at 20 000 μl l-1 (2%) CO2 for both established and rain roots. Upon lowering CO2 to 1 000 μl l-1 after exposure to concentrations up to 10000 μl l-1 CO2 , inhibition of respiration was reversible. Uptake of the vital stain neutral red by root cortical cells was reduced to zero, indicating cell death, in about 4 h at 2% CO2 , substantiating the detrimental effects of high soil CO2 concentrations on roots of A. deserti . This CO2 response may explain why roots of desert succulents tend to occur in porous, well-aerated soils. 相似文献
11.
The responses of individual stomata to CO2 concentrations ranging from 0 to 900 μmol mol−1 air were analysed in Ipomoea pes-caprae L. Sweet (Convolvulaceae). The stomata were directly observed using a measurement system that permitted continuous observation of stomatal movement under controlled light and CO2 conditions. A CO2 concentration of 350 μmol mol−1 or higher induced stomatal closure, whereas concentrations below 350 μmol mol−1 did not. The time lag before stomatal closure decreased with increasing CO2 concentration, as did the steady-state aperture of the stomata after a change in CO2 concentration. However, the rate of stomatal closure increased with increasing CO2 concentration. Therefore, not only the stomatal closure rate but also the time from the CO2 concentration change to the beginning of stomatal closure changed with increasing CO2 concentration. These results suggest that atmospheric CO2 may be the stimulus for the closure of guard cells. No significant differences were observed between adaxial and abaxial stomata in terms of their responses to CO2 . However, heterogeneous responses were detected between neighbouring stomata on each leaf surface. 相似文献
12.
We present, for the first time, the oxygen response kinetics of mitochondrial respiration measured in intact leaves (sunflower and aspen). Low O2 concentrations in N2 (9–1500 ppm) were preset in a flow-through gas exchange measurement system, and the decrease in O2 concentration and the increase in CO2 concentration as result of leaf respiration were measured by a zirconium cell O2 analyser and infrared-absorption CO2 analyser, respectively. The low O2 concentrations little influenced the rate of CO2 evolution during the 60-s exposure. The initial slope of the O2 uptake curve on the dissolved O2 concentration basis was relatively constant in leaves of a single species, 1.5 mm s−1 in sunflower and 1.8 mm s−1 in aspen. The apparent K 0.5 (O2 ) values ranged from 0.33 to 0.67 μ M in sunflower and from 0.33 to 1.1 μ M in aspen, mainly because of the variation of the maximum rate, V max (leaf temperature 22°C). The initial slope of the O2 response of respiration characterizes the catalytic efficiency of terminal oxidases, an important parameter of the respiratory machinery in leaves. The plateau of the response characterizes the activity of the mitochondrial electron transport chain and is subject to regulations in accordance with the necessity for ATP production. The relatively low oxygen conductivity of terminal oxidases means that in leaves, less than 10% of the photosynthetic oxygen can be reassimilated by mitochondria. 相似文献
13.
Two Italian CO2 springs allowed us to study the long-term effect of a 350–2600 μ mol mol–1 increase in CO2 concentrations on the surface structures of leaves of Quercus ilex L. Carbon dioxide increased the quantity of cuticular waxes, above an apparent threshold of 750 μ mol mol–1 CO2 . Leaf wettability was not modified by CO2 concentrations. Reduction in stomatal frequency was observable up to 750 μ mol mol–1 CO2 , the slope being almost the same as that estimated for the increase in CO2 concentration from pre-industrial times to the present. At higher concentrations, CO2 seemed to exert no more impact on stomatal frequency. 相似文献
14.
M. DURANCEAU J. GHASHGHAIE F. BADECK E. DELEENS & G. CORNIC 《Plant, cell & environment》1999,22(5):515-523
The variations in δ 13 C in both leaf carbohydrates (starch and sucrose) and CO2 respired in the dark from the cotyledonary leaves of Phaseolus vulgaris L. were investigated during a progressive drought. As expected, sucrose and starch became heavier (enriched in 13 C) with decreasing stomatal conductance and decreasing p i / p a during the first half (15 d) of the dehydration cycle. Thereafter, when stomata remained closed and leaf net photosynthesis was near zero, the tendency was reversed: the carbohydrates became lighter (depleted in 13 C). This may be explained by increased p i / p a but other possible explanations are also discussed. Interestingly, the variations in δ 13 C of CO2 respired in the dark were correlated with those of sucrose for both well-watered and dehydrated plants. A linear relationship was obtained between δ 13 C of CO2 respired in the dark and sucrose, respired CO2 always being enriched in 13 C compared with sucrose by ≈ 6‰. The whole leaf organic matter was depleted in 13 C compared with leaf carbohydrates by at least 1‰. These results suggest that: (i) a discrimination by ≈ 6‰ occurs during dark respiration processes releasing 13 C-enriched CO2 ; and that (ii) this leads to 13 C depletion in the remaining leaf material. 相似文献
15.
Stomatal density (SD) and stomatal conductance ( g s ) can be affected by an increase of atmospheric CO2 concentration. This study was conducted on 17 species growing in a naturally enriched CO2 spring and belonging to three plant communities. Stomatal conductance, stomatal density and stomatal index (SI) of plants from the spring, which were assumed to have been exposed for generations to elevated [CO2 ], and of plants of the same species collected in a nearby control site, were compared. Stomatal conductance was significantly lower in most of the species collected in the CO2 spring and this indicated that CO2 effects on g s are not of a transitory nature but persist in the long term and through plant generations. Such a decrease was, however, not associated with changes in the anatomy of leaves: SD was unaffected in the majority of species (the decrease was only significant in three out of the 17 species examined), and also SI values did not vary between the two sites with the exception of two species that showed increased SI in plants grown in the CO2 -enriched area. These results did not support the hypothesis that long-term exposure to elevated [CO2 ] may cause adaptive modification in stomatal number and in their distribution. 相似文献
16.
KAY-MAY MIYAGI TOSHIHIKO KINUGASA KOUKI HIKOSAKA TADAKI HIROSE 《Global Change Biology》2007,13(10):2161-2170
Elevated atmospheric CO2 concentration ([CO2 ]) stimulates seed mass production in many species, but the extent of stimulation shows large variation among species. We examined (1) whether seed production is enhanced more in species with lower seed nitrogen concentrations, and (2) whether seed production is enhanced by elevated [CO2 ] when the plant uses more N for seed production. We grew 11 annuals in open top chambers that have different [CO2 ] conditions (ambient: 370 μmol mol−1 , elevated: 700 μmol mol−1 ). Elevated [CO2 ] significantly increased seed production in six out of 11 species with a large interspecific variation (0.84–2.12, elevated/ambient [CO2 ]). Seed nitrogen concentration was not correlated with the enhancement of seed production by elevated [CO2 ]. The enhancement of seed production was strongly correlated with the enhancement of seed nitrogen per plant caused by increased N acquisition during the reproductive period. In particular, legume species tended to acquire more N and produced more seeds at elevated [CO2 ] than non-nitrogen fixing species. Elevated [CO2 ] little affected seed [N] in all species. We conclude that seed production is limited primarily by nitrogen availability and will be enhanced by elevated [CO2 ] only when the plant is able to increase nitrogen acquisition. 相似文献
17.
The effect of long-term water stress on photosynthetic carbon metabolism in Casuarina equisetifolia Forst. & Forst. was analysed by measuring CO2 assimilation, stomatal conductance, the quantum yield of photosystem II ( Φ PSII ), enzyme activities, and the levels of photosynthetic intermediates and carbohydrates. CO2 assimilation decreased under water stress while the intercellular CO2 concentration ( C i ) as estimated by gas exchange measurements remained high. However, the estimates of C i from measurements of Φ PSII suggest that the decrease in photosynthesis can be explained in terms of stomatal closure. Water stress decreased total stromal fructose-1,6-bisphosphatase activity and did not alter the activities and activation states of ribulose bisphosphate carboxylase oxygenase and NADP-dependent malate dehydrogenase (NADP-MDH). The concentration of photosynthetic metabolites, glucose, fructose and sucrose decreased, whereas starch concentrations increased under drought conditions. 相似文献
18.
Photosynthetic and respiratory responses to temperature and light of three Alaskan tundra growth forms 总被引:2,自引:0,他引:2
Photosynthetic and respiratory response of four Alaskan tundra species comprising three growth forms were investigated in the laboratory using an infrared gas analysis system. Vaccinium vitis-idaea , a dwarf evergreen shrub, demonstrated a low photosynthetic capacity: Pmax = 1 mg CO2 g dry wt−1 h−1 ; Topt < 10°C. Betula nana , a deciduous shrub, had a high relatively photosynthetic capacity: Pmax = 14 mg CO2 g dry wt−1 h−1 ; Topt 17°C. Two graminoid (sedge) species, Carex aquatilis and Eriophorum vaginalum , showed different responses. Carex showed a high photosynthetic capacity: Pmax = 20 mg CO2 g dry wt−1 h−1 ; Topt 22°C. Eriophorum vaginatum demonstrated an intermediate photosynthetic capacity of 4 mg CO2 g dry wt−1 h−1 at saturated light levels. Leaf dark respiration, up to 20°C, was approximately the same for all species. The patterns of root respiration among species was opposite to the trend in photosynthesis. Vaccinium vitis-idaea had the highest rate of root respiration and B. nana the lowest ( C aquatilis was not measured). Correlation between leaf nitrogen content (%) and photosynthetic capacity was high. Hypothesized growth form relationships explained differences in photosynthetic capacity between the deciduous shrub and evergreen shrub, but did little to account for differences between the two sedges. Differences in rooting patterns between species may affect tissue nutrient content, carbon flux rates, and carbon balance. 相似文献
19.
Abstract. This paper discusses the consequences of non-uniform (= patchwise) stomatal closure on the estimation of gas exchange parameters. The estimation of the partial pressure of internal CO2 (ci ) appears to be little sensitive to complete non-uniform stomatal closure. During the process of closure of these patches, however, a lower ci will be calculated. For gas exchange measurements done at low wind speeds, it can be shown that an error is made in the partitioning of the total vapour transfer resistance into boundary layer and stomatal resistance. This error influences the calculated total transfer resistance of gases other than water vapour (e.g. CO2 ). The apparent negative internal gas concentrations that have sometimes been found in fumigation experiments with SO2 can possibly be explained by this error. 相似文献
20.
Respiration in a future, higher-CO2 world 总被引:20,自引:9,他引:11
J. S. AMTHOR 《Plant, cell & environment》1991,14(1):13-20
Abstract. Apart from its impact on global warming, the annually increasing atmospheric [CO2 ] is of interest to plant scientists primarily because of its direct influence on photosynthesis and photorespiration in C3 species. But in addition, 'dark' respiration, another major component of the carbon budget of higher plants, may be affected by a change in [CO2 ] independent of an increase in temperature. Literature pertaining to an impact of [CO2 ] on respiration rate is reviewed. With an increase in [CO2 ], respiration rate is increased in some cases, but decreased in others. The effects of [CO2 ] on respiration rate may be direct or indirect. Mechanisms responsible for various observations are proposed. These proposed mechanisms relate to changes in: (1) levels of nonstructural carbohydrates, (2) growth rate and structural phytomass accumulation, (3) composition of phytomass, (4) direct chemical interactions between CO2 and respiratory enzymes, (5) direct chemical interactions between CO2 and other cellular components, (6) dark CO2 fixation rate, and (7) ethylene biosynthesis rate. Because a range-of (possibly interactive) effects exist, and present knowledge is limited, the impact of future [CO2 ] on respiration rate cannot be predicted. Theoretical considerations and types of experiments that can lead to an increase in the understanding of this issue are outlined. 相似文献