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1.
Baxter R.; Bell S. A.; Sparks T.H.; Ashenden T.W.; Farrar J.F. 《Journal of experimental botany》1995,46(8):917-929
Agrostis capillaris L.5, Festuca vivipara L. and Poaalpina L.were grown in outdoor open-top chambers at either ambient (340 3µmol mol1) or elevated (6804µmol mol1)concentrations of atmospheric carbon dioxide (CO2) for periodsfrom 79189 d. Photosynthetic capacity of source leaves of plants grown atboth ambient and elevated CO2 concentrations was measured atsaturating light and 5% CO2. Dark respiration of leaves wasmeasured using a liquid phase oxygen electrode with the buffersolution in equilibrium with air (21% O2, 0.034% CO2). Photo-syntheticcapacity of P. alpina was reduced by growth at 680 µmolmol1 CO2 by 105 d, and that of F. vivipara was reducedat 65 d and 189 d after CO2 enrichment began, suggesting down-regulationor acclimation. Dark respiration of successive leaf blades ofall three species was unaltered by growth at 680 relative to340 µmol mol1 CO2. In F. vivipara, leaf respirationrate was markedly lower at 189 d than at either 0 d or 65 d,irrespective of growth CO2 concentration. There was a significantlylower total non-structural carbohydrate (TNC) concentrationin the leaf blades and leaf sheaths of A. capillaris grown at680µmol mol1 CO2. TNC of roots of A. capillariswas unaltered by CO2 treatment. TNC concentration was increasedin both leaves and sheaths of P. alpina and F. vivipara after105 d and 65 d growth, respectively. A 4-fold increase in thewater-soluble fraction (fructan) in P. alpina and in all carbohydratefractions in F. vivipara accounted for the increased TNC content. In F. vivipara the relationship between leaf photosyn-theticcapacity and leaf carbohydrate concentration was such that therewas a strong positive correlation between photosynthetic capacityand total leaf N concentration (expressed on a per unit structuraldry weight basis), and total nitrogen concentration of successivemature leaves reduced with time. Multiple regression of leafphotosynthetic capacity upon leaf nitrogen and carbohydrateconcentrations further confirmed that leaf photosynthetic capacitywas mainly determined by leaf N concentration. In P. alpina,leaf photosynthetic capacity was mainly determined by leaf CHOconcentration. Thus there is evidence for down-regulation ofphotosynthetic capacity in P. alpina resulting from increasedcarbohydrate accumulation in source leaves. Leaf dark respiration and total N concentration were positivelycorrelated in P. alpina and F. vivipara. Leaf dark respirationand soluble carbohydrate concentration of source leaves werepositively correlated in A. capillaris. Changes in source leafphotosynthetic capacity and carbohydrate concentration of plantsgrown at ambient or elevated CO2 are discussed in relation toplant growth, nutrient relations and availability of sinks forcarbon. Key words: Elevated CO2, Climate change, grasses, carbohydrate partitioning, photosynthesis, respiration 相似文献
2.
The photosynthetic response to CO2 concentration, light intensityand temperature was investigated in water hyacinth plants (Eichhorniacrassipes (Mart.) Solms) grown in summer at ambient CO2 or at10000 µmol(CO2) mol1 and in winter at 6000 µmol(CO2)mol1 Plants grown and measured at ambient CO2 had highphotosynthetic rate (35 µmo1(CO2) m2 s1),high saturating photon flux density (15002000) µmolm2 s1 and low sensitivity to temperature in therange 2040 °C. Maximum photosynthetic rate (63 µmol(CO2)m2 s1) was reached at an internal CO2 concentrationof 800 µmol mol1. Plants grown at high CO2 in summerhad photosynthetic capacities at ambient CO2 which were 15%less than for plants grown at ambient CO2, but maximum photosyntheticrates were similar. Photosynthesis by plants grown at high CO2and high light intensity had typical response curves to internalCO2 concentration with saturation at high CO2, but for plantsgrown under high CO2 and low light and plants grown under lowCO2 and high light intensity photosynthetic rates decreasedsharply at internal CO2 concentrations above 1000 µmol1. Key words: Photosynthesis, CO2, enrichment, Eichhornia crassipes 相似文献
3.
Wheeler T.R.; Hong T.D.; Ellis R.H.; Batts G.R.; Morison J.I.L.; Hadley P. 《Journal of experimental botany》1996,47(5):623-630
Winter wheat (Triticum aestivum L. cv. Hereward) was grown inthe field inside polyethylene-covered tunnels at a range oftemperatures at either 380 or 684 µmol mol1 CO2.Serial harvests were taken from anthesis until harvest maturity.Grain yield was reduced by warmer temperatures, but increasedby CO2 enrichment at all temperatures. During grain-filling,individual grain dry weight was a linear function of time fromanthesis until mass maturity (attainment of maximum grain dryweight) within each plot. The rate of progress to mass maturity(the reciprocal of time to mass maturity) was a positive linearfunction of mean temperature, but was not affected by CO2 concentration.The rate of increase in grain dry weight per ear was 2.0 mgd1 greater per 1 C rise, and was 8.0 mg d1 greaterat 684 compared with 380 µmol mol1 CO2 at a giventemperature. The rate of increase in harvest index was 1.0%d1 in most plots at 380 µmol mol1 CO2 andin open field plots, compared with 1.18% d1 in all plotsat 684 µmol mol1 CO2. Thus, the increased rateof grain growth observed at an elevated CO2 concentration couldbe attributed partly to a change in the partitioning of assimilatesto the grain. In contrast, the primary effect of warmer temperatureswas to shorten the duration of grain-filling. The rate of graingrowth at a given temperature and the rate of increase in harvestindex were only independent of the number of grains per earabove a critical grain number of 2324 grains per ear({small tilde}20 000 grains m2). Key words: Winter wheat, grain growth, temperature, CO2, harvest index, critical grain number 相似文献
4.
Plants of Phaseolus vulgaris L were grown from seed in open-topgrowth chambers at present day (350 µmol mol1)and double the present day (700 µmol mol1) atmosphericCO2 concentration with either low (L, without additional nutrientsolution) or relatively high (H, with additional nutrient solution)nutrient supply Measurements of assimilation rate, stomatalconductance and water use efficiency were started 17 d aftersowing on each fully expanded, primary leaf of three plantsper treatment Measurements were made in external CO2 concentrations(C2) of 200, 350, 450, 550 and 700 µmol mol1 andrelated to both Ca and to C1, the mean intercellular space CO2concentration Fully adjusted, steady state measurements weremade after approx 2 h equilibration at each CO2 concentration The rate of CO2 assimilation by leaves increased and stomatalconductance decreased similarly over the range of Ca or C1 inall four CO2 and nutrient supply treatments but both assimilationrate and stomatal conductance were higher in the high nutrientsupply treatment than in the low nutrient treatment The relationbetween assimilation rate or stomatal conductance and C1 wasnot significantly different amongst plants grown in present-dayor elevated CO2 concentration in either nutrient supply treatment,i e there was no evidence of down regulation of photosynthesisor stomatal response Increase in CO2 concentration from 350to 700 µmol mol1 doubled water use efficiency ofindividual leaves in the high nutrient supply treatment andtripled water use efficiency in the low nutrient supply treatment The results support the hypothesis that acclimation phenomenaresult from unbalanced growth that occurs after the seed reservesare exhausted, when the supply of resources becomes growth limiting CO2 enrichment, Phaseolus vulgaris L., net CO2 assimilation rate, stomatal conductance, water use efficiency 相似文献
5.
Pascopyrum smithii (C3) andBouteloua gracilis (C4) are importantforage grasses native to the Colorado shortgrass steppe. Thisstudy investigated photosynthetic responses of these grassesto long-term CO2enrichment and temperature in relation to leafnonstructural carbohydrate (TNC) and [N]. Glasshouse-grown seedlingswere transferred to growth chambers and grown for 49 d at twoCO2concentrations (380 and 750 µmol mol-1) at 20 and 35°C, and two additional temperatures (25 and 30 °C) at750 µmol mol-1CO2. Leaf CO2exchange rate (CER) was measuredat a plant's respective growth temperature and at two CO2concentrationsof approx. 380 and 700 µmol mol-1. Long-term CO2enrichmentstimulated CER in both species, although the response was greaterin the C3,P. smithii . Doubling the [CO2] from 380 to 750 µmolmol-1stimulated CER ofP. smithii slightly more in plants grownand measured at 30 °C compared to plants grown at 20, 25or 35 °C. CO2-enriched plants sometimes exhibited lowerCER when compared to ambient-grown controls measured at thesame [CO2], indicating photosynthetic acclimation to CO2growthregime. InP. smithii , such reductions in CER were associatedwith increases in TNC and specific leaf mass, reductions inleaf [N] and, in one instance, a reduction in leaf conductancecompared to controls. InB. gracilis , photosynthetic acclimationwas observed more often, but significant changes in leaf metabolitelevels from growth at different [CO2] were generally less evident.Temperatures considered optimal for growth (C3: 20 °C; C4:35 °C) sometimes led to CO2-induced accumulations of TNCin both species, with starch accumulating in the leaves of bothspecies, and fructans accumulating only inP. smithii. Photosynthesisof both species is likely to be enhanced in future CO2-enrichedand warmer environments, although responses will sometimes beattenuated by acclimation. Acclimation; blue grama (Bouteloua gracilis (H.B.K.) Lag ex Steud.); leaf nitrogen concentration; nonstructural carbohydrates; photosynthesis; western wheatgrass (Pascopyrum smithii (Rydb.) Love) 相似文献
6.
Effects of nitrogen on Pinus palustris foliar respiratory responses to elevated atmospheric CO2 concentration 总被引:2,自引:0,他引:2
Mitchell R.J.; Runion G.B.; Prior S.A.; Rogers H.H.; Amthor J.S.; Henning F.P. 《Journal of experimental botany》1995,46(10):1561-1567
Indirect effects of atmospheric CO2 concentration [CO2], onlongleaf pine (Pinus palustris Mill.) foliage respiration werestudied by growing trees in a factorial arrangement of low andhigh [CO2] (369 and 729µmol CO2 mol1) and low andhigh N (40 and 400 kg ha1 yr1). Direct effectsof [CO2] on leaf respiration were tested by measuring respirationrates of foliage from all treatments at two CO2 levels (360and 720µmol CO2mol1) at the time of measurement.Elevated CO2 did not directly or indirectly affect leaf respirationwhen expressed on a leaf area or mass basis, but a significantincrease in respiration per unit leaf N was observed in treesgrown in elevated [CO2] (indirect response to elevated [CO2]).The lack of a [CO2] effect on respiration, when analysed onan area or mass basis, may have resulted from combined effectsof [CO2] on factors that increase respiration (e.g. greateravailability of non-structural carbohydrates stimulating growthand carbon export from leaves) and on factors that decreaserespiration (e.g. lower N concentration leading to lower constructioncosts and maintenance requirements). Thus, [CO2] affected factorsthat influence respiration, but in opposing ways. Key words: Pinus palustris, elevated CO2, nitrogen, foliar, respiration 相似文献
7.
The variations of leaf carbohydrate concentration, carbon isotopediscrimination () of leaf soluble carbohydrate, gas-exchangeand growth during a soil drying cycle under 350 and 700 µmolmol-1 CO2 concentrations ([CO2]) inQuercus robur seedlings wereanalysed. In well-watered conditions, a doubling of [CO2] causedan increase of CO2 assimilation rate (A) ( +47%) and a decreaseof stomatal conductance for water vapour (g) (25%),anddoubled the intrinsic water-use efficiency (A/g). The valuesof A were not affected by elevated [CO2] which was consistentwith the 2-fold increase of A/g. Elevated [CO2 also significantlyincreased sucrose and starch leaf concentrations as well asaerial growth and plant dry weight. The stimulating effect ofCO2 enrichment on A and A/g was maintained in moderate droughtconditions, but disappeared in the most severe drought conditions.Drought induced an increase of hexose concentrations in both[CO2], but this effect was more pronounced under elevated [CO2],which may contribute to increase osmoregulation. From the onsetof drought, starch was depleted in both [CO2]. Carbon isotopediscrimination decreased in response to drought, which correspondedto an increase in A/g according to the two-step model of isotopicdiscrimination. In contrast, the A/g values derived from instantaneousleaf gas-exchange measurements decreased along the drying cycle.The discrepancy observed between the two independent estimatesof water-use efficiency is discussed in terms of time-scaleintegration. The results obtained with the isotopic approachusing soluble carbohydrate suggest a predominant stomatal limitationof CO2 assimilation in response to drought. Soil drying cycle,elevated CO2, leaf gas-exchange, leaf carbohydrate concentrations,carbon isotope discrimination, growth, Quercus robur. Key words: soil drying cycle, elevated CO2, leaf gas-exchange, leaf carbohydrate concentrations, carbon isotope discrimination, growth, Quercus robur 相似文献
8.
Acclimation of single plants of Lolium temulentum to changing[CO2] was studied on plants grown in controlled environmentsat 20°C with an 8 h photoperiod. In the first experimentplants were grown at 135 µ;mol m2 s1 photosyntheticphoton flux density (PPFD) at 415µl l1 or 550µll1 [CO2] with some plants transferred from the lowerto the higher [CO2] at emergence of leaf 4. In the second experimentplants were grown at 135 and 500 µmol m2 s1PPFD at 345 and 575 µl l1 [CO2]. High [CO2] during growth had little effect on stomatal density,total soluble proteins, chlorophyll a content, amount of Rubiscoor cytochrome f. However, increasing [CO2] during measurementincreased photosynthetic rates, particularly in high light.Plants grown in the higher [CO2] had greater leaf extension,leaf and plant growth rates in low but not in high light. Theresults are discussed in relation to the limitation of growthby sink capacity and the modifications in the plant which allowthe storage of extra assimilates at high [CO2]. Key words: Lolium, carbon dioxide, photosynthesis, growth, stomatal density 相似文献
9.
Clonal plants of white clover (Trifolium repens L ), whollydependent on N2 fixation, were grown for 6 weeks in controlledenvironments providing either (C680 regime) 23/18 °C day/nighttemperatures and a CO2, concentration of 680 µmol mol1,or (C340 regime) 20/15 °C day/night temperatures and a CO2,concentration of 340 µmol mol1 During the firsthalf of the experimental period the C680 plants grew fasterthan their C340 counterparts so that by week 3 they were twicethe weight this 2 1 superiority in weight persisted until theend of the experiment The faster initial growth of the C680plants was based on an approx 70 % increase in leaf numbersand an approx 30 % increase in their individual area Initially,specific leaf area (cm2 g1 leaf) was lower in C680 thanin C340 leaves but became similar in the latter half of theexperiment Shoot organ weights, including petioles and stolons,reflected the C680 plant's better growth in terms of photosyntheticsurface Throughout, C680 plants invested less of their weightin root than C340 plants and this disparity increased with timeAcetylene reduction assays showed that nitrogenase activityper unit nodule weight was the same in both C680 and C340 plantsBoth groups of plants invested about the same fraction of totalweight in nodules Nitrogen contents of plant tissues were similarirrespective of growth regime, but C680 expanded leaves containedslightly less nitrogen and their stolons slightly more nitrogenthan their C340 counterparts However, C680 leaves containedmore non-structural carbohydrate Young, unshaded C680 leavespossessed larger palisade cells, packed more tightly withinthe leaf, than equivalent C340 leaves The reason for the C680regime's loss of superiority in relative growth rate duringthe second half of the experiment was not clear, but more accumulationof non-structural carbohydrate, constriction of root growthand increased self-shading appear to be the most likely causes Trifolium repens, white clover, elevated CO2, elevated temperature, growth, N2 fixation, leaf structure 相似文献
10.
The stomatal response of seedlings grown in 360 or 720 µmolmol1 to irradiance and leaf-to-air vapour pressure deficit(VPD) at both 360 and 720 µmol mol1 to CO2 wasmeasured to determine how environmental factors interact withCO2 enrichment to affect stomatal conductance. Seedlings offour species with different conductances and life histories,Cercis canadensis (L.), Quercus rubra (L.), Populus deltoides(Bartr. ex Marsh.) P. nigra (L.), and Pinus taeda (L.), weremeasured in hopes of identifying general responses. Conductanceof seedlings grown at 360 and 720 µmol mol1 CO2were similar and responded in the same manner to measurementCO2 concentration, irradiance and VPD. Conductance was lowerfor all species when measured at 720 than when measured at 360µmol mol1 CO2 at both VPDs ({small tilde}1.5 and{small tilde}2.5 kPa) and all measured irradiances greater thanzero (100, 300, 600,>1600 µmol m2 S2)The average decrease in conductance due to measurement in elevatedCO2 concentration was 32% for Cercis, 29% for Quercus, 26% forPopulus, and 11% for Pinus. For alt species, the absolute decreasein conductance due to measurement in CO2 enrichment decreasedas irradiance decreased or VPD increased. The proportional decreasedue to measurement in CO2 enrichment decreased in three of eightcases: from 0.46 to 0.10 in Populus and from 0.18 to 0.07 inPinus as irradiance decreased from>1600 to 100 µmolm2 s1 and from 0.35 to 0.24 in Cercis as VPD increasedfrom 1.3 to 2.6 kPa. Key words: Stomatal conductance, CO2 enrichment, irradiance, vapour pressure deficit 相似文献
11.
The Effects of CO2 Enrichment and Nutrient Supply on Growth Morphology and Anatomy of Phaseolus vulgaris L. Seedlings 总被引:2,自引:0,他引:2
Plants of Phaseolus vulgaris were grown from seed in open-topgrowth chambers at the present (P, 350 µmol mol1)atmospheric CO2 concentration and at an elevated (E, 700 µmolmol1) CO2 concentration, and at low (L, without additionalnutrient solution) and high (H, with additional nutrient solution)nutrient supply for 28 d The effects of CO2 and nutrient availabilitywere examined on growth, morphological and biochemical characteristics Leaf area and dry mass were significantly increased by CO2 enrichmentand by high nutrient supply Stomatal density, stomatal indexand epidermal cell density were not affected by elevated CO2concentration or by nutrient supply Leaf thickness respondedpositively to CO2 increasing particularly in mesophyll areaas a result of cell enlargement Intercellular air spaces inthe mesophyll decreased slightly in plants grown in elevatedCO2 Leaf chlorophyll content per unit area or dry mass was significantlylower in elevated CO2 grown plants and increased significantlywith increasing nutrient availability The content of reducingcarbohydrates of leaves, stem, and roots was not affected byCO2 but was significantly increased by nutrient addition inall plant parts Starch content in leaves and stem was significantlyincreased by elevated CO2 concentration and by high nutrientsupply Phaseolus vulgaris, elevated atmospheric CO2, CO2-nutrient interaction, stomatal density, leaf anatomy, chlorophyll, carbohydrates, starch 相似文献
12.
CO2 Assimilation and Partitioning of Carbon in Maize Plants Deprived of Orthophosphate 总被引:3,自引:0,他引:3
KHAMIS SAADI; CHAILLOU SYLVAIN; LAMAZE THIERRY 《Journal of experimental botany》1990,41(12):1619-1625
In order to study the effects of inorganic phosphate (P1) starvationon C4plants, 3-week-old maize plants (Zea maysL cv. Brulouis)were grown in a growth chamber on a nutrient solution withoutP1 over 22 d During the first 2 weeks, Pi-starved plants grewas well as control plants The Pi concentration in the planttissue decreased rapidly with time, which suggests that normalbiomass production can be maintained at the expense of internalP1 In addition, photosynthetic CO2 assimilation measured 4-6h after dawn was not affected, but the concentration of glucose,sucrose, and starch in leaves was much higher than in the controls14CO2 pulse-chase experiments earned out on the ninth day oftreatment showed that 14CO2 assimilation was perturbed duringthis initial period, resulting in a larger flow of carbon toboth starch and sucrose At the beginning of the third week ofP1 starvation (15 d after treatment) 14C incorporation intosucrose stayed high relative to controls but this was not thecase for starch At the end of the third week of P1-deficiency,shoot growth was considerably reduced and fresh weight was onlyone-third of that of the control plants. The P1 concentrationof both the leaf and root tissues was less than 1.0 µmolg1 FW compared to 20-25µmol g1 FW in the controls.Photosynthetic CO2 assimilation was reduced and the leaf concentrationof sucrose and starch, which had begun to decrease after theend of the second week of P1 limitation, became lower than inthe controls. These results obtained on maize plants show thatphotosynthesis and carbon partitioning between sucrose and starchwere strongly affected by P1 deficiency, similar to C3 species. Key words: CO2 assimilation, corn, orthophosphate deficiency, starch, sucrose 相似文献
13.
Effects of elevated carbon dioxide on three montane grass species: I. Growth and dry matter partitioning 总被引:4,自引:0,他引:4
Baxter R.; Ashenden T.W.; Sparks T.H.; Farrar J.F. 《Journal of experimental botany》1994,45(3):305-315
Upland grasslands are a major component of natural vegetationwithin the UK. Such grasslands support slow growing relativelystable plant communities. The response of native montane grassspecies to elevated atmospheric carbon dioxide concentrationshas received little attention to date. Of such studies, mosthave only focused on short-term (days to weeks) responses, oftenunder favourable controlled environment conditions. In thisstudy Agrostis caplllaris L.5, Festuca vivipara L. and Poa alpinaL. were grown under semi-natural conditions in outdoor open-topchambers at either ambient (340µmol mol1) or elevated(680µmol mol1) concentrations of atmospheric carbondioxide (CO2 for periods from 79 to 189 d, with a nutrient availabilitysimilar to that of montane Agrostis-Fescue grassland in Snowdonia,N. Wales. Whole plant dry weight was increased for A. capillarisand P. alpina, but decreased for F. vivipara, at elevated CO2.Major components of relative growth rate (RGR) contributingto this change at elevated CO2 were transient changes in specificleaf area (SLA) and leaf area ratio (LAR). Despite changes ingrowth rate at 680 µmol mol1 CO2, partitioningof dry weight between shoot and root in plants of A. capillarisand P. alpina was unaltered. There was a significant decreasein shoot relative to root growth at elevated CO2 in F. viviparawhich also showed marked discoloration of the leaves and increasedsenescence of the foliage. Key words: Allometry, growth analysis, elevated CO2, grasses 相似文献
14.
Effect of elevated CO2 and nutrient status on growth, dry matter partitioning and nutrient content of Poa alpina var. vivipara L. 总被引:1,自引:0,他引:1
Poa alpina var. vivipara L. was grown in an atmosphere containingeither 340 or 680 µmol CO2 mol1 within controlledenvironment chambers. The available nutrient regime was variedby altering the supply of nitrogen and phosphorus within a completenutrient solution. At a high, but not low, N and P supply regime,elevated CO2 markedly increased growth. Differences betweennutrient supply, but not atmospheric CO2 concentration, alteredthe allometric relations between root and shoot. Net photosynthesisof mature leaf blades and leaf N and P concentration were reducedin plants grown at the elevated CO2 concentration. The question was asked: is it possible to ascribe all of theseeffects to elevated CO2 or are some due to nutrient deficiencycaused by dilution with excess carbon? Several criteria, includingthe nutrient content of sink tissue, root:shoot allometry andthe use of divalent cations to estimate integrated water flowsare suggested in order to make this distinction. It is concludedthat only at a low supply of N and P1 and elevated CO2 concentration,was low leaf N concentration due to induced nutrient deficiency.The data are consistent with a model where the capacity of sinksto use photosynthetically assimilated carbon sets both the rateof import into those sinks (and thus rate of export from sourceleaves) and the rate of photosynthesis of source leaves themselves. Key words: Poa alpina L., growth, photosynthesis, carbohydrate, export, nitrogen, phosphorus 相似文献
15.
Ceulemans R.; Taylor G.; Bosac C.; Wilkins D.; Besford R.T. 《Journal of experimental botany》1997,48(9):1681-1689
The effects of elevated CO2 were studied on the photosyntheticgas exchange behaviour and leaf physiology of two contrastingpoplar (Populus) hybrids grown and treated in open top chambers(OTCs in Antwerp, Belgium) and in closed glasshouse cabinets(GHCs in Sussex, UK). The CO2 concentrations used in the OTCswere ambient and ambient +350 µmol mol1 while inthe GHCs they were c. 360 µmol mol1 versus 719µmol mol1. Measurements of photosynthetic gas exchangewere made for euramerican and interamerican poplar hybrids incombination with measurements of dark respiration rate and Rubiscoactivity. Significant differences in the leaf anatomy and structure(leaf mass per area and chlorophyll content) were observed betweenthe leaves grown in the OTCs and those grown in the GHCs. ElevatedCO2 stimulated net photosynthesis in the poplar hybrids after1 month in the GHCs and after 4 months in the OTCs, and therewas no evidence of downward acclimation (or down-regulation)of photosynthesis when the plants in the two treatments weremeasured in their growth CO2 concentration. There was also noevidence of down-regulation of Rubisco activity and there wereeven examples of increases in Rubisco activity. Rubisco exerteda strong control over the light-saturated rate of photosynthesis,which was demonstrated by the close agreement between observednet photosynthetic rates and those that were predicted fromRubisco activities and Michaelis-Menten kinetics. After 17 monthsin elevated CO2 in the OTCs there was a significant loss ofRubisco activity for one of the hybrid clones, i.e. Beaupr,but not for clone Robusta. The effect of the CO2 measurementconcentration (i.e. the short-term treatment effect) on netphotosynthesis was always larger than the effect of the growthconcentration in both the OTCs or GHCs (i.e. the longterm growthCO2 effect), with one exception. For the interamerican hybridBeaupr dark respiration rates in the OTCs were not significantlyaffected by the elevated CO2 concentrations. The results suggestthat for rapidly growing tree species, such as poplars, thereis little evidence for downward acclimation of photosynthesiswhen plants are exposed to elevated CO2 for up to 4 months;longer term exposure reveals loss of Rubisco activity. Key words: Elevated CO2, Populus, Rubisco, photosynthesis, chlorophyll content 相似文献
16.
Long-term effects of atmospheric carbon dioxide concentration(ambient or 700 µmol mol1) and air temperature(simulation of field conditions or + 4 C) on leaf photosyntheticrate were examined in Lolium perenne L. cv. Vigor, exposed tonatural illumination during winter. Photosynthetic capacitywas compared over a range of air temperatures and photon fluxdensities of photosynthetically active radiation which wererepresentative of winter climate (515 C and 0500µmol m2s1), with CO2 level during measurementsimilar to that during the experimental period. Long-term exposureto increased air temperature reduced leaf CO2 fixation capacityby 23% (averaged over all measurement conditions), resultingfrom a decline in lightsaturated uptake rate, but not in incident-lightquantum efficiency. CO2- stimulation was largely absent in plantsgrown in ambient temperature, but pronounced in plants grownunder +4 C, where it compensated for two-thirds of the 23%drop. This enhancing effect of elevated CO2 level on leaf CO2uptake rate observed in the warmer treatment, was strongly dependenton measurement temperature, increasing from 5% at 5 C, to upto 32% at 15 C. Measurements of chlorophyll fluorescence anddry matter corresponded with the observed changes in assimilationcapacity, which could not be attributed to a deteriorated nitrogenstatus of the leaves as there was a similar N content on anarea basis. Several hypotheses are considered to explain theobserved CO2-temperature interactions. Key words: Acclimation, chlorophyll fluorescence, elevated CO2 level, global warming, low temperature 相似文献
17.
CAMPBELL WILLIAM J.; ALLEN L. H. JR; BOWES GEORGE 《Journal of experimental botany》1990,41(4):427-433
Photosynthetic rates of outdoor-grown soybean (Glycine max L.Merr. cv. Bragg) canopies increased with increasing CO2 concentrationduring growth, before and after canopy closure (complete lightinterception), when measured over a wide range of solar irradiancevalues. Total canopy leaf area was greater as the CO2 concentrationduring growth was increased from 160 to 990 mm3 dm3.Photosynthetic rates of canopies grown at 330 and 660 mm3 CO2dm3 were similar when measured at the same CO2 concentrationsand high irradiance. There was no difference in ribulose bisphosphatecarboxylase/oxygenase (rubisco) activity or ribulose 1,5-bisphosphate(RuBP) concentration between plants grown at the two CO2 concentrations.However, photosynthetic rates averaged 87% greater for the canopiesgrown and measured at 660 mm3 CO2 dm3. A 10°C differencein air temperature during growth resulted in only a 4°Cleaf temperature difference, which was insufficient to changethe photosynthetic rate or rubisco activity in canopies grownand measured at either 330 or 660 mm3 CO2 dm3. RuBP concentrationsdecreased as air temperature during growth was increased atboth CO2 concentrations. These data indicate that the increasedphotosynthetic rates of soybean canopies at elevated CO2 aredue to several factors, including: more rapid development ofthe leaf area index; a reduction in substrate CO2 limitation;and no downward acclimation in photosynthetic capacity, as occurin some other species. Key words: CO2 concentration, soybean, canopy photosynthesis 相似文献
18.
Differentiating Day from Night Effects of High Ambient [CO2] on the Gas Exchange and Growth of Xanthium strumarium L. Exposed to Salinity Stress 总被引:2,自引:0,他引:2
Sodium chloride, at a concentration of 88 mol m-3in half strengthHoagland nutrient solution, increased dry weight per unit areaofXanthium strumarium L. leaves by 19%, and chlorophyll by 45%compared to plants grown without added NaCl at ambient (350µmol mol-1) CO2concentration. Photosynthesis, per unitleaf area, was almost unaffected. Even so, over a 4-week period,growth (dry weight increment) was reduced in the salt treatmentby 50%. This could be ascribed to a large reduction in leafarea (>60%) and to an approx. 20% increase in the rate ofdark respiration (Rd). Raising ambient [CO2] from zero to 2000 µmol mol-1decreasedRd in both control and salinized plants (by 20% at 1000, andby 50% at 2000 µmol mol-1CO2concentration) compared toRd in the absence of ambient CO2. High night-time [CO2] hadno significant effect on growth of non-salinized plants, irrespectiveof day-time ambient [CO2]. Growth reduction caused by salt wasreduced from 51% in plants grown in 350 µmol mol-1throughoutthe day, to 31% in those grown continuously in 900 µmolmol-1[CO2]. The effect of [CO2] at night on salinized plants depended onthe daytime CO2concentration. Under 350 µmol mol-1day-time[CO2], 900 µmol mol-1at night reduced growth over a 4-weekperiod by 9% (P <0.05) and 1700 µmol mol-1reduced itby 14% (P <0.01). However, under 900 µmol mol-1day-time[CO2], 900vs . 350 µmol mol-1[CO2] at night increasedgrowth by 17% (P <0.01). It is concluded that there is both a functional and an otiose(functionless) component to Rd, which is increased by salt.Under conditions of low photosynthesis (such as here, in thelow day-time [CO2] regime) the otiose component is small andhigh night-time [CO2] partly suppresses functional Rd, therebyreducing salt tolerance. In plants growing under conditionswhich stimulate photosynthesis (e.g. with increased daytime[CO2]), elevated [CO2] at night suppresses mainly the otiosecomponent of respiration, thus increasing growth. Consequently,in regions of adequate water and sunlight, the predicted furtherelevation of the world atmospheric [CO2] may increase plantsalinity tolerance. Xanthium strumarium ; respiration; photosynthesis; salt stress; sodium chloride; carbon dioxide; atmosphere 相似文献
19.
Single clonal plants of white clover (Trifolium repens L) grownfrom explants in a Perlite rooting medium, and dependent fornitrogen on N2 fixation in root nodules, were grown for severalweeks in controlled environments which provided two regimesof CO2, and temperature 23/18 °C day/night temperaturesat 680 µmol mol1 CO2, (C680), and 20/15 °Cday/night temperatures at 340 µmol mol1 CO2 (C340)After 34 weeks of growth, when the plants were acclimatedto the environmental regimes, leaf and whole-plant photosynthesisand respiration were measured using conventional infra-red gasanalysis techniques Elevated CO2 and temperature increased ratesof photosynthesis of young, fully expanded leaves at the growthirradiance by 1729%, despite decreased stomatal conductancesand transpiration rates Water use efficiency (mol CO2 mol H2O1)was also significantly increased Plants acclimated to elevatedCO2, and temperature exhibited rates of leaf photosynthesisvery similar to those of C340 leaves instantaneouslyexposed to the C680 regime However, leaves developed in theC680 regime photosynthesised less rapidly than C340 leaves whenboth were exposed to a normal CO2, and temperature environmentIn measurements where irradiance was varied, the enhancementof photosynthesis in elevated CO2 at 23 °C increased graduallyfrom approx 10 % at 100 µmol m1 s1 to >27 % at 1170 µmol m2 s1 In parallel, wateruse efficiency increased by 2040 % at 315 µmolm2 s1 In parallel, water use efficiency increasedby 2040 % at 315 µmol m2 s1 In parallel,water use efficiency increased by 2040 % at 315 µmolm2 s1 In parallel, water use efficiency increasedby 2040 % at 315 µmol m2 s1 to approx100 % at the highest irradiance Elevated CO2, and temperatureincreased whole-plant photosynthesis by > 40 %, when expressedin terms of shoot surface area or shoot weight No effects ofelevated CO2 and temperature on rate of tissue respiration,either during growth or measurement, were established for singleleaves or for whole plants Dependence on N2, fixation in rootnodules appeared to have no detrimental effect on photosyntheticperformance in elevated CO2, and temperature Trifolium repens, white clover, photosynthesis, respiration, elevated CO2, elevated temperature, water use efficiency, N2 fixation 相似文献
20.
Temperature Effects on Rice at Elevated CO2 Concentration 总被引:1,自引:0,他引:1
The continuing increase in atmospheric carbon dioxide concentration([CO2]) and projections of possible future increases in globalairtemperatures have stimulated interest in the effects of theseclimate variables on agriculturally important food crops. Thisstudywas conducted to determine the effects of [CO2] and temperatureon rice (Oryza sativa L., cv. IR30). Rice plants weregrownseason-long in outdoor, naturally sunlit, controlled-environment,plant growth chambers in temperature regimes ranging from 25/18/21°Cto 37/30/34°C (daytime dry bulb air temperature/night-timedry bulb air temperature/paddy water temperature)and [CO2] of660 µmol CO2 mol1 air. An ambient chamber was maintainedat a [CO2] of 330 µmol mol1 and temperature regimesof 28/21/25°C. Carbon dioxide enrichment at 28/21/25°Cincreased both biomass accumulation and tillering and increasedgrain yield by 60%. In the 660 µmol mol1 [CO2]treatment, grain yield decreased from 10.4 to 1.0 Mg ha1with increasing temperature from 28/21/25°C to the 37/30/34°Ctemperature treatment. Across this temperature range, the numberof panicles plant1 nearly doubled while the number ofseeds panicle1 declined sharply. These results indicatethat while future increases in atmospheric [CO2] are likelyto be beneficial to rice growth and yield, potentially largenegative effects on rice yield are possible if air temperaturesalso rise. Key words: Oryza sativa, CO2, temperature, growth, yield 相似文献