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1.
Summary Cotton and maize plants were grown under full sunlight in glass houses containing normal ambient partial pressure of CO 2 (330±20 bar) and enriched partial pressure of CO 2 (640 ±15 bar) with four levels of nitrogen nutrient. In 40 day old cotton plants grown in high CO 2, there was a 2-fold increase in day weight and a 1.6-fold increase in leaf area compared with plants grown in ambient CO 2. In 30 day old maize plants there was only 20% increase in dry weight in plants grown in 640 bar CO 2 compared with plants grown in 330 bar and no significant increase in leaf area. In both species, at both CO 2 treatments, dry weight and leaf area decreased in similar proportion with decreased nitrogen nutrient.The increase of leaf area in cotton plants at high CO 2 caused a reduction of total nitrogen on a dry weight basis. In cotton assimilation rate increased 1.5 fold when plants were grown with high nitrogen and high CO 2. The increase was less at lower levels of nitrate nutrient. There was a 1.2 fold increase in assimilation rate in maize grown at high CO 2 with high nitrate nutrient.Cotton and maize grown in high CO 2 had a lower assimilation rate in ambient CO 2 compared to plants grown in normal ambient air. This difference was due to the reduction in RuBP carboxylase activity. Water use efficiency was doubled in both cotton and maize plants grown at high CO 2 in all nutrient treatments. However, this increase in water use efficiency was due primarily to reduced transpiration in some treatments and to increased assimilation in others. These data show that plant responses to elevated atmospheric partial pressure of CO 2 depend on complex of partially compensatory processes which are not readily predictable. 相似文献
2.
A common observation in plants grown in elevated CO 2 concentration is that the rate of photosynthesis is lower than expected from the dependence of photosynthesis upon CO 2 concentration in single leaves of plants grown at present CO 2 concentration. Furthermore, it has been suggested that this apparent down regulation of photosynthesis may be larger in leaves of plants at low nitrogen supply than at higher nitrogen supply. However, the available data are rather limited and contradictory. In this paper, particular attention is drawn to the way in which whole plant growth response to N supply constitutes a variable sink strength for carbohydrate usage and how this may affect photosynthesis. The need for further studies of the acclimation of photosynthesis at elevated CO 2 in leaves of plants whose N supply has resulted in well-defined growth rate and sink activity is emphasised, and brief consideration is made of how this might be achieved.Abbreviations A
rate of CO 2 assimilation
- C i
internal CO 2 concentration
- PCR
photosynthetic carbon reduction
- Rubisco
Ribulose 1,5-bisphosphate carboxylase/oxygenase
- RuBP
ribulose 1,5-bisphosphate 相似文献
3.
The capacity for photosynthesis is often affected when plants are grown in air with elevated CO 2 partial pressure. We grew Phaseolus vulgaris L. in 35 and 65 Pa CO 2 and measured photosynthetic parameters. When assayed at the growth CO 2 level, photosynthesis was equal in the two CO 2 treatments. The maximum rate of ribulose-1,5-bisphosphate (RuBP) consumption was lower in plants grown at 65 Pa, but the CO 2 partial pressure at which the maximum occurred was higher in the high-CO 2-grown plants, indicating acclimation to high CO 2. The acclimation of RuBP consumption to CO 2 involved a reduction of the activity of RuBP carboxylase which resulted from reduced carbamylation, not a loss of protein. The rate of RuBP consumption declined with CO 2 when the CO 2 partial pressure was above 50Pa in plants grown under both CO 2 levels. This was caused by feedback inhibition as judged by a lack of response to removing O 2 from the air stream. The rate of photosynthesis at high CO 2 was lower in the high-CO 2-grown plants and this was correlated with reduced activity of sucrose-phosphate synthase. This is only the second report of O 2-insensitive photosynthesis under growth conditions for plants grown in high CO 2. 相似文献
4.
Elevated atmospheric carbon dioxide partial pressures have been shown to have variable direct and indirect effects on plant respiration rates. In this study, growth, leaf respiration, and leaf nitrogen and carbohydrate partitioning were measured in Gossypium hirsutum L. grown in 35 and 65 Pa CO 2 for 30d. Growth and maintenance coefficients of leaf respiration were estimated using gas exchange techniques both at night and during the day. Elevated CO 2 stimulated biomass production (107%) and net photo-synthetic rates (35–50%). Total day-time respiration (R d) was not significantly affected by growth CO 2 partial pressure. However, night respiration (R n) of leaves grown in 65 Pa CO 2 was significantly greater than that of plants grown in 35 Pa CO 2. Correlation of R d and R n with leaf expansion rates indicated that plants in both CO 2 treatments had equivalent growth respiration coefficients but maintenance respiration was significantly greater in elevated CO 2. Increased maintenance coefficients in elevated CO 2 appeared to be related to increased starch accumulation rather than to changes in leaf nitrogen. 相似文献
5.
We grew loblolly and ponderosa pine seedlings in a factorial experiment with two CO 2 partial pressures (35 and 70 Pa), and two nitrogen treatments (1.0 and 3.5 mol m ?3 NH 4+), for one growing season to examine the effects of carbon and nitrogen availability on leaf construction cost. Growth in elevated CO 2 reduced leaf nitrogen concentrations by 17 to 40%, and increased C:N by 22 to 68%. Elevated N availability increased leaf N concentrations and decreased C:N. Non-structural carbohydrates increased in high-CO 2-grown loblolly seedlings, except in fascicles from low N, and in ponderosa primary and fascicle leaves grown in high N. In loblolly, increases in starch were nearly 2-fold greater than the increases in soluble sugars. In ponderosa, only the soluble sugars were affected by CO 2. Leaf construction cost (g glucose g ?1 dm) varied by 9.3% across all treatments. All of the variation in loblolly leaf construction cost could be explained by changes in non-structural carbohydrates. A model of the response of construction cost to changes in the mass of different biochemical fractions suggests that the remainder of the variation in ponderosa, not explained by non-structural carbohydrates, is probably attributable to changes in lignin, phenolic or protein concentrations. 相似文献
6.
Experiments were performed to determine if growth at elevated partial pressure of CO 2 altered the sensitivity of leaf water vapour conductance and rate of CO 2 assimilation to the leaf-to-air difference in the partial pressure of water vapour (Δw). Comparisons were made between plants grown and measured at 350 and 700 μPa Pa ?1 partial pressures of CO 2 for amaranth, soybean and sunflower grown in controlled environment chambers, soybean grown outdoors in pots, and orchard grass grown in field plots. In amaranth, soybean and orchard grass, both the absolute and the relative sensitivity of conductance to Δw at the leaf surface were less in plants grown and measured at the elevated CO 2. In sunflower, there was no change in the sensitivity of conductance to Δw for the two CO 2 partial pressures. Tests in soybeans and amaranth showed that the change in sensitivity resulted from elevated CO 2 during the measurement of the Δw response. Assimilation rate of CO 2 was not altered by Δw in amaranth, which has C 4 metabolism. In sunflower, the assimilation rate of plants grown and measured at elevated CO 2 was insensitive to Δw, consistent with the response of assimilation rate to intercellular CO 2 partial pressure in the prevailing range. In soybean, the sensitivity of assimilation rate to Δw was not different between CO 2 treatments, in contrast to what would be expected from the response of assimilation rate to intercellular CO 2 partial pressure. 相似文献
7.
Photosynthetic rates and photosynthate partitioning were studied in three-week-old soybean [ Glycine max (L.) Merr. cv. Williams] plants exposed to either ambient (35 Pa) or elevated (70 Pa) CO 2 in controlled environment chambers. Ambient CO 2-grown plants also were given a single 24 h treatment with 70 Pa CO 2 1 d prior to sampling. Photosynthetic rates of ambient CO 2-grown plants initially increased 36% when the measurement CO 2 was doubled from 35 to 70 Pa. Photosynthetic rates of the third trifoliolate leaf, both after 1 and 21 d of elevated CO 2 treatment, were 30 to 45% below those of ambient CO 2-grown plants when measured at 35 Pa CO 2. These reduced photosynthetic rates were not due to increased stomatal resistance and were observed for 2 to 8 h after plants given 1 d of CO 2 enrichment were returned to ambient CO 2. Initial and total ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activities, percent activation, Rubisco protein, soluble protein and leaf chlorophyll content were similar in all CO 2 treatments. Quantum yields of photosynthesis, determined at limiting irradiances and at 35 Pa CO 2, were 0.049±0.003 and 0.038±0.005 mol CO 2 fixed per mol quanta for ambient and elevated CO 2-grown plants, respectively (p<0.05). Leaf starch and sucrose levels were greater in plants grown at 70 than at 35 Pa CO 2. Starch accumulation rates during the day were greater in ambient CO 2-grown plants than in plants exposed to elevated CO 2 for either 1 or 21 d. However, the percentage of C partitioned to starch relative to total C fixed was unaffected by 1 d of CO 2 enrichment. The above results showed that both photosynthetic and starch accumulation rates of soybean leaflets measured at 35 Pa CO 2 were temporarily reduced after 1 and 21 d of CO 2 enrichment. The biochemical mechanism affecting these responses was not identified.Abbreviations SLW-
specific leaf weight (g m –2)
- Rubisco-
ribulose 1,5-bisphosphate carboxylase/oxygenase
- Rul-
5bisP, ribulose 1,5 bisphosphate
- DAP-
days after planting
- SAR-
starch accumulation rate
- C i-
intercellular CO 2 concentration 相似文献
8.
Summary Little is known about the effects of enriched CO 2 environments, which are anticipated to exist in the next century, on natural plant-insect herbivore interactions. To begin to understand such effects on insect growth and survival, I reared both early and penultimate instar larvae of the buckeye, Junonia coenia (Lepidoptera: Nymphalidae), on leaves from one of their major hostplants, plantain, Plantago lanceolata (Plantaginaceae), grown in either ambient (350 PPM) or high (700 PPM) CO 2 atmospheres. Despite consuming more foliage, early instar larvae experienced reduced growth on high CO 2-grown compared to ambient CO 2-grown leaves. However, survivorship of early instar larvae was unaffected by the CO 2 treatment. Larval weight gain was positively correlated with the nitrogen concentration of the plant material and consumption was negatively correlated with foliar nitrogen concentration, whereas neither larval weight gain nor consumption were significantly correlated with foliar water or allelochemical concentrations. In contrast, penultimate instar larvae had similar growth rates on ambient and high CO 2-grown leaves. Significantly higher consumption rates on high CO 2-grown plants enabled penultimate instar larvae to obtain similar amounts of nitrogen in both treatments. These larvae grew at similar rates on foliage from the two CO 2 treatments, despite a reduced efficiency of conversion of ingested food (ECI) on the low nitrogen, high CO 2-grown plants. However, nitrogen utilization efficiencies (NUE) were unaffected by CO 2 treatment. Again, for late instar larvae, consumption rates were negatively correlated with foliar nitrogen concentrations, and ECI was also very highly correlated with leaf nitrogen; foliar water or allelochemical concentrations did not affect either of these parameters. Differences in growth responses of early and late instar larvae to lower nitrogen, high-CO 2 grown foliage may be due to the inability of early instar larvae to efficiently process the increased flow of food through the gut caused by additional consumption of high CO 2 foliage. 相似文献
9.
Phosphorus-deficient spinach plants were grown by transferring them to nutrient solutions without PO 4. Photosynthetic rates were measured at a range of intercellular CO 2 partial pressures from 50–500 bar and then the leaves were freeze-clamped in situ to measure ribulose bisphosphate carboxylase (Rubisco) activity and metabolite concentrations. Compared with control leaves, deficient leaves had significantly lower photosynthetic rates, percentage activation of Rubisco, and amounts of ribulose bisphosphate and 3-phosphoglycerate at all CO 2 partial pressures. After feeding 10 mM PO 4 to the petioles of detached deficient leaves, all these measurements increased within 2 hours. At atmospheric CO 2 partial pressure the photosynthetic rate was stimulated in 19 mbar O 2 compared with 200 mbar. At higher CO 2 partial pressures this stimulation was less but the percentage stimulation in deficient leaves was no different from controls in either CO 2 partial pressure. It was concluded that phosphorus deficiency affects both Rubisco activity and the capacity for ribulose bisphosphate regeneration, and possible causes are discussed.Abbreviations A
CO 2 assimilation rate
- C i
intercellular CO 2 partial pressure
- PGA
3-phosphoglycerate
- RuP 2
ribulose 1,5-bisphosphate
- Rubisco
RuP 2 carboxylase/oxygenase 相似文献
10.
To test whether different nitrogen form (nitrate or ammonium) in substrate can alter the response to elevated partial pressure of CO 2 (pCO 2) plants of perennial ryegrass ( Lolium perenne cv. Bastion) were grown from seeds in growth chambers under pCO 2 of either 35 Pa (ambient, CA) or 70 Pa (elevated, CE) in a hydroponic system (with nutrient and pH control) for 24 d. Nitrogen was supplied as ammonium, nitrate or an equimolar mixture of both N forms. Under CE plants grew faster than their counterparts under CA during the first 14 d but after 23 d of cultivation stimulation disappeared. Despite the strong positive effect of mixed forms of N on plant growth, the beneficial effect of CE was similar to that in the other two N treatments. However, the almost alike final growth response to CE had different underlying mechanisms in different N treatments. Plants supplied with nitrate as a sole source of nitrogen had lower leaf mass ratio but much higher specific leaf area compared to plants supplied with ammonium. The decrease in the content of leaf organic N (per unit of structural dry mass) under CE was found only in leaves of plants supplied with ammonium on day 14. Nevertheless, the available form of N evidently contributes to changes of leaf N content under CE. The high levels of N and non-structural saccharides in plants supplied with ammonium at CE suggest that the CO 2 response of these plants was controlled by factors other than amount of available carbon and nitrogen. 相似文献
11.
Small birch plants ( Betula pendula Roth.) were grown from seed for periods of up to 70d in a climate chamber at optimal nutrition and at present (350 μmol mol ?1) or elevated (700 μmol mol ?1) concentrations of atmospheric CO 2. Nutrients were sprayed over the roots in Ingestad-type units. Relative growth rate and net assimilation rate were slightly higher at elevated CO 2, whereas leaf area ratio was slightly lower. Smaller leaf area ratio was associated with lower values of specific leaf area. Leaves grown at elevated CO 2 had higher starch concentrations (dry weight basis) than leaves grown at present levels of CO 2. Biomass allocation showed no change with CO 2, and no large effects on stem height, number of side shoots and number of leaves were found. However, the specific root length of fine roots was higher at elevated CO 2. No large difference in the response of carbon assimilation to intercellular CO 2 concentration (A/C i curves) were found between CO 2 treatments. When measured at the growth environments, the rates of photosynthesis were higher in plants grown at elevated CO 2 than in plants grown at present CO 2. Water use efficiency of single leaves was higher in the elevated treatment. This was mainly attributable to higher carbon assimilation rate at elevated CO 2. The difference in water use efficiency diminished with leaf age. The small treatment difference in relative growth rate was maintained throughout the experiment, which meant that the difference in plant size became progressively greater. Thus, where plant nutrition is sufficient to maintain maximum growth, small birch plants may potentially increase in size more rapidly at elevated CO 2. 相似文献
12.
Wheat ( Triticum aestivum L. cv Yecora 70) plants were grown with various concentrations of nitrate nitrogen available to the roots. Sampling of flag leaves began after they had reached full expansion and continued throughout senescence. Rates of gas exchange, ribulose-1,5-bisphosphate (RuP 2) carboxylase activity, and the amounts of chlorophyll, soluble protein, nitrogen, and phosphorus were determined for each flag leaf. Rate of CO 2 assimilation was uniquely related to total leaf nitrogen irrespective of nutrient treatment, season, and leaf age. Assimilation rate increased with leaf nitrogen, but the slope of the relationship declined markedly when leaf nitrogen exceeded 125 millimoles nitrogen per square meter. Chlorophyll content and RuP 2 carboxylase activity were approximately proportional to leaf nitrogen content. As leaves aged, RuP 2 carboxylase activity and calculated Hill activity declined in parallel. With normal ambient partial pressure of CO 2, the intercellular partial pressure of CO 2 was always such that rate of assimilation appeared colimited by RuP 2 carboxylation and RuP 2 regeneration capacity. The initial slope of rate of CO2 assimilation against intercellular partial pressure of CO2 varied nonlinearly with carboxylase activity. It is suggested that this was due to a finite conductance to CO2 diffusion in the wall and liquid phase which causes a drop in CO2 partial pressure between the intercellular spaces and the site of carboxylation. A double reciprocal plot was used to obtain an estimate of the transfer conductance. 相似文献
13.
Cotton plants ( Gossypium hirsutum L. var Deltapine 90) and radish plants ( Raphanus sativus L var Round Red) were grown under full sunlight using a factorial combination of atmospheric CO 2 concentrations (350 µmol mol -1 and 700 µmol mol -1) and humidities (35% and 90% RH at 32 °C during the day). Cotton plants showed large responses to increased humidity and to doubled CO 2. In cotton plants, the enhanced dry matter yield due to doubled CO 2 concentration was 1.6-fold greater at low humidity than at high humidity. Apart from the direct effect of elevated CO 2 level on photosynthesis, the greater effect of doubled CO 2 concentration on dry matter yield at low humidity was probably due to: (1) increased leaf water potential caused by reduction of transpiration resulting from the negative CO 2 response of stomata to increased CO 2 concentration the consequence being greater leaf area expansion; (2) reduction of CO 2 assimilation rate at low humidity and normal CO 2 concentration as a result of humidity response of stomata causing reduction of intercellular CO 2 concentration. In contrast, apart from the very early stage of development, radish plants do not respond to increased humidity but had a relatively large response to doubled CO 2 concentration. Furthermore, due to the determinate growth pattern as well as having a prominent storage root, the extra photoassimilate derived at doubled CO 2 level is allocated to the storage root.Abbreviatios DAE
day after emergence
- LAD
leaf areal density (leaf dry weight/leaf area)
- LAR
leaf area ratio (leaf area/plant dry weight)
- NAR
net assimilation rate
- c i
internal CO 2 concentration
- PPFD
photosynthetic photon flux density
- RGR
relative growth rate
- RLAGR
relative leaf area growth rate
- VPD
vapour pressure deficit 相似文献
14.
Plants grown at elevated CO 2 often acclimate such that their photosynthetic capacities are reduced relative to ambient CO 2-grown plants. Reductions in synthesis of photosynthetic enzymes could result either from reduced photosynthetic gene expression or from reduced availability of nitrogen-containing substrates for enzyme synthesis. Increased carbohydrate concentrations resulting from increased photosynthetic carbon fixation at elevated CO 2 concentrations have been suggested to reduce the expression of photosynthetic genes. However, recent studies have also suggested that nitrogen uptake may be depressed by elevated CO 2, or at least that it is not increased enough to keep pace with increased carbohydrate production. This response could induce a nitrogen limitation in elevated-CO 2 plants that might account for the reduction in photosynthetic enzyme synthesis. If CO 2 acclimation were a response to limited nitrogen uptake, the effects of elevated CO 2 and limiting nitrogen supply on photosynthesis and nitrogen allocation should be similar. To test this hypothesis we grew non-nodulating soybeans at two levels each of nitrogen and CO 2 concentration and measured leaf nitrogen contents, photosynthetic capacities and Rubisco contents. Both low nitrogen and elevated CO 2 reduced nitrogen as a percentage of total leaf dry mass but only low nitrogen supply produced significant decreases in nitrogen as a percentage of leaf structural dry mass. The primary effect of elevated CO 2 was to increase non-structural carbohydrate storage rather than to decrease nitrogen content. Both low nitrogen supply and elevated CO 2 also decreased carboxylation capacity ( Vcmax) and Rubisco content per unit leaf area. However, when Vcmax and Rubisco content were expressed per unit nitrogen, low nitrogen supply generally caused them to increase whereas elevated CO 2 generally caused them to decrease. Finally, elevated CO 2 significantly increased the ratio of RuBP regeneration capacity to Vcmax whereas neither nitrogen supply nor plant age had a significant effect on this parameter. We conclude that reductions in photosynthetic enzyme synthesis in elevated CO 2 appear not to result from limited nitrogen supply but instead may result from feedback inhibition by increased carbohydrate contents. 相似文献
15.
Physiological processes that modulate photosynthetic acclimation to rising atmospheric CO 2 concentration are subjects of intense discussion recently. Apparently, the down-regulation of photosynthesis under elevated CO 2 is not understood clearly. In the present study, the response of soybean ( Glycine max L.) to CO 2 enrichment was examined in terms of nitrogen partitioning and water relation. The plants grown under potted conditions without combined N application were exposed to either ambient air (38 Pa CO 2) or CO 2 enrichment (100 Pa CO 2) for short (6 days) and long (27 days). Plant biomass, apparent photosynthetic rate, transpiration rate and 15N uptake and partitioning were measured consecutively after elevated CO 2 treatment. Long-term exposure reduced photosynthetic rate, stomatal conductance and transpiration rate. In contrast, short-term exposure increased biomass production of soybean due to increase in dry weight of leaves. Leaf N concentration tended to decrease with CO 2 enrichment, however such difference was not true for stem and roots.A close correlation was observed between transpiration rate and 15N partitioned into leaves, suggesting that transpiration plays an important role on nitrogen partitioning to leaves. In conclusion existence of a feed back mechanism for photosynthetic acclimation has been proposed. Down-regulation of photosynthetic activity under CO 2 enrichment is caused by decreasing leaf N concentration, and reduced rate of transpiration owing to decreased stomatal conductance is partially responsible for poor N translocation. 相似文献
16.
Rising levels of atmospheric CO 2 will have profound, direct effects on plant carbon metabolism. In this study we used gas exchange measurements, models describing the instantaneous response of leaf net CO 2 assimilation rate ( A) to intercellular CO 2 partial pressure ( Ci), in vitro enzyme activity assay, and carbohydrate assay in order to investigate the photosynthetic responses of wheat (Triticum aestivum L., cv. Wembley) to growth under elevated partial pressures of atmospheric CO 2 ( Ca). At flag leaf ligule emergence, the modelled, in vivo, maximum carboxylation velocity for RuBisCO was significantly lower in plants grown at elevated Ca than in plants grown at ambient Ca (70 Pa compared with 40 Pa). By 12 d after ligule emergence, no significant difference in this parameter was detectable. At ligule emergence, plants grown at elevated Ca exhibited reduced in vitro initial activities and activation states of RuBisCO. At their respective growth Ci values, the photosynthesis of 40-Pa-grown plants was sensitive to p(O 2) and to p(CO 2) whereas that of 70-Pa-grown plants was insensitive. Both sucrose and starch accumulated more rapidly in the leaves of plants grown at 70 Pa. At flag leaf ligule emergence, modelled non-photorespiratory respiration in the light ( Rd) was significantly higher in 70-Pa-grown plants than in 40-Pa-grown plants. By 12 d after ligule emergence no significant differences in Rd were detectable. 相似文献
17.
Soil N availability may play an important role in regulating the long-term responses of plants to rising atmospheric CO 2 partial pressure. To further examine the linkage between above- and belowground C and N cycles at elevated CO 2, we grew clonally propagated cuttings of Populus grandidentata in the field at ambient and twice ambient CO 2 in open bottom root boxes filled with organic matter poor native soil. Nitrogen was added to all root boxes at a rate equivalent
to net N mineralization in local dry oak forests. Nitrogen added during August was enriched with 15N to trace the flux of N within the plant-soil system. Above-and belowground growth, CO 2 assimilation, and leaf N content were measured non-destructively over 142 d. After final destructive harvest, roots, stems,
and leaves were analyzed for total N and 15N.
There was no CO 2 treatment effect on leaf area, root length, or net assimilation prior to the completion of N addition. Following the N addition,
leaf N content increased in both CO 2 treatments, but net assimilation showed a sustained increase only in elevated CO 2 grown plants. Root relative extension rate was greater at elevated CO 2, both before and after the N addition. Although final root biomass was greater at elevated CO 2, there was no CO 2 effect on plant N uptake or allocation. While low soil N availability severely inhibited CO 2 responses, high CO 2 grown plants were more responsive to N. This differential behavior must be considered in light of the temporal and spatial
heterogeneity of soil resources, particularly N which often limits plant growth in temperate forests. 相似文献
18.
Various aspects of the biochemistry of photosynthetic carbon assimilation in C 3 plants are integrated into a form compatible with studies of gas exchange in leaves. These aspects include the kinetic properties of ribulose bisphosphate carboxylase-oxygenase; the requirements of the photosynthetic carbon reduction and photorespiratory carbon oxidation cycles for reduced pyridine nucleotides; the dependence of electron transport on photon flux and the presence of a temperature dependent upper limit to electron transport. The measurements of gas exchange with which the model outputs may be compared include those of the temperature and partial pressure of CO 2( p(CO 2)) dependencies of quantum yield, the variation of compensation point with temperature and partial pressure of O 2( p(O 2)), the dependence of net CO 2 assimilation rate on p(CO 2) and irradiance, and the influence of p(CO 2) and irradiance on the temperature dependence of assimilation rate.Abbreviations RuP 2
ribulose bisphosphate
- PGA
3-phosphoglycerate
- C= p(CO 2)
partial pressure of CO 2
- O= p(O 2)
partial pressure of O 2
- PCR
photosynthetic carbon reduction
- PCO
photorespiratory carbon oxidation 相似文献
19.
Seedlings of loblolly pine ( Pinus taeda L.) were grown under varying conditions of soil nitrogen and atmospheric carbon dioxide availability to investigate the interactive effects of these resources on the energetic requirements for leaf growth. Increasing the ambient CO 2 partial pressure from 35 to 65 Pa increased seedling growth only when soil nitrogen was high. Biomass increased by 55% and photosynthesis increased by 13% after 100 days of CO 2 enrichment. Leaves from seedlings grown in high soil nitrogen were 7.0% more expensive on a g glucose g –1 dry mass basis to produce than those grown in low nitrogen, while elevated CO 2 decreased leaf cost by 3.5%. Nitrogen and CO 2 availability had an interactive effect on leaf construction cost expressed on an area basis, reflecting source-sink interactions. When both resources were abundant, leaf construction cost on an area basis was relatively high (81.8±3.0 g glucose m –2) compared to leaves from high nitrogen, low CO 2 seedlings (56.3±3.0 g glucose m –2) and low nitrogen, low CO 2 seedlings (67.1±2.7 g glucose m –2). Leaf construction cost appears to respond to alterations in the utilization of photoassimilates mediated by resource availability. 相似文献
20.
Rates of CO 2 assimilation and leaf conductances to CO 2 transfer were measured in plants of Zea mays during a period of 14 days in which the plants were not rewatered, and leaf water potential decreased from −0.5 to −8.0 bar. At any given ambient partial pressure of CO 2, water stress reduced rate of assimilation and leaf conductance similarly, so that intercellular partial pressure of CO 2 remained almost constant. At normal ambient partial pressure of CO 2, the intercellular partial pressure of CO 2 was estimated to be 95 microbars. This is the same as had been estimated in plants of Zea mays grown with various levels of nitrogen supply, phosphate supply and irradiance, and in plants of Zea mays examined at different irradiances. After leaves of Phaseolus vulgaris L. and Eucalyptus pauciflora Sieb. ex Spreng had been exposed to high irradiance in an atmosphere of CO2-free N2 with 10 millibars O2, rates of assimilation and leaf conductances measured in standard conditions had decreased in similar proportions, so that intercellular partial pressure of CO2 remained almost unchanged. As the conductance of each epidermis that had not been directly irradiated had declined as much as that in the opposite, irradiated surface it was hypothesized that conductance may have been influenced by photoinhibition within the mesophyll tissue. 相似文献
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