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1.
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
2.
Responses of CO2 assimilation to changes in irradiance: laboratory and field data and a model for beans (Phaseolus vulgaris L.) 总被引:1,自引:0,他引:1
The responses of net CO2 assimilation to sudden changes in irradiancewere studied in Phaseolus vulgaris L. in the laboratory andthe field. For irradiance changes between 50 µmol m2s1 to 350 µmol m2 s1 in the laboratory,assimilation rate increased with half-times of 2.7 and 4.1 minin well-watered and water-stressed plants, respectively. Ina field experiment with a change in irradiance from 400 to 1200µmol m2 s1 the response was faster (half-time=c.1.2 min). In all cases when irradiance was returned to a lowvalue, assimilation declined rapidly with a half-time of approximately1 min, which approached the time resolution of the gas-exchangesystem. The corresponding changes in stomatal conductance in responseto both increasing and decreasing irradiance were much slowerthan the assimilation responses, indicating that biochemicalprocesses, rather than CO2 supply, primarily determined theactual rate of assimilation in these experiments. The conceptof stomatal limitation to photosynthesis is discussed in relationto these results. A simple model for assimilation in a fluctuating light environmentis proposed that depends on a steadystate light response curve,an induction lag on increasing irradiance, andan induction-state memory. The likely importance of taking accountof such induction lags in natural canopy microclimates is considered. Key words: Models, Phaseolus vulgaris, photosynthetic induction, CO2 assimilation, stomatal limitation, sunflecks, water stress 相似文献
3.
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
4.
The poplar clones Columbia River, Beaupre, Robusta and Raspaljehave been investigated in the present (350 µmol mol1)and double the present (700 µmol mol1) atmosphericCO2 concentration. Cuttings were planted in pots and were grownin open-top chambers inside a glasshouse for 92 d. Stomatal density, stomatal index, length of stomatal pore andepidermal cell density were not affected by CO2 enrichment inany of the clones. Lack of differences in stomatal density orindex indicate that there were no direct effects of CO2 enrichmenton the initiation of the number of stomata during ontogenesisor on epidermal cell expansion at a later stage. Stomatal conductance decreased because of the effect of CO2on stomatal opening. The average reduction in both adaxial andabaxial surface has been estimated at 41%. Beaupre showed thelargest response of stomatal conductance and Columbia Riverthe smallest. Poplar clones, CO2 enrichment, stomatal density, stomatal length, stomatal conductance 相似文献
5.
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
6.
The mechanism of SO2-induced changes in stomatal conductance(g) of alder was examined to determine if SO2 affects guardcell function directly or indirectly through the SO2-inducedchanges in photosynthesis. During experimental fumigations at SO2 concentrations of 33µmol m3 (0.08 µl l1), stomatal closurepreceded declines in net photosynthetic rate (A), indicatingthat SO2 can directly affect guard cells. From these and otherstudies it appears that the sequence of A and g responses maybe influenced by SO2 concentration as well as by species. Fumigation with SO2 did not cause increases in g, even whenthe intercellular substomatal CO2 concentration (ci) was reducedby 50 µmol mol1. Increases in g are not attributableto SO2 effects on the CO2-based stomatal control system. Key words: Air pollution, Alnus serrulata, gas exchange, stomata, sulphur dioxide 相似文献
7.
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
8.
Biochemical Limitations to Carbon Assimilation in C3 Plants--A Retrospective Analysis of the A/Ci Curves from 109 Species 总被引:9,自引:0,他引:9
Species-specific differences in the assimilation of atmosphericCO2 depends upon differences in the capacities for the biochemicalreactions that regulate the gas-exchange process. Quantifyingthese differences for more than a few species, however, hasproven difficult. Therefore, to understand better how speciesdiffer in their capacity for CO2 assimilation, a widely usedmodel, capable of partitioning limitations to the activity ofribulose-1,5-bisphosphate carboxylase-oxygenase, to the rateof ribulose 1,5-bisphosphate regeneration via electron transport,and to the rate of triose phosphate utilization was used toanalyse 164 previously published A/Ci, curves for 109 C3 plantspecies. Based on this analysis, the maximum rate of carboxylation,Vcmax, ranged from 6µmol m2 s1 for the coniferousspecies Picea abies to 194µmol m2 s1 forthe agricultural species Beta vulgaris, and averaged 64µmolm2 s1 across all species. The maximum rate ofelectron transport, Jmax, ranged from 17µmol m2s1 again for Picea abies to 372µmol m2 s1for the desert annual Malvastrum rotundifolium, and averaged134µmol m2 s1 across all species. A strongpositive correlation between Vcmax and Jmax indicated that theassimilation of CO2 was regulated in a co-ordinated manner bythese two component processes. Of the A/Ci curves analysed,23 showed either an insensitivity or reversed-sensitivity toincreasing CO2 concentration, indicating that CO2 assimilationwas limited by the utilization of triose phosphates. The rateof triose phosphate utilization ranged from 4·9 µmolm2 s1 for the tropical perennial Tabebuia roseato 20·1 µmol m2 s1 for the weedyannual Xanthium strumarium, and averaged 10·1 µmolm2 s1 across all species. Despite what at first glance would appear to be a wide rangeof estimates for the biochemical capacities that regulate CO2assimilation, separating these species-specific results intothose of broad plant categories revealed that Vcmax and Jmaxwere in general higher for herbaceous annuals than they werefor woody perennials. For annuals, Vcmax and Jmax averaged 75and 154 µmol m2 s1, while for perennialsthese same two parameters averaged only 44 and 97 µmolm2 s1, respectively. Although these differencesbetween groups may be coincidental, such an observation pointsto differences between annuals and perennials in either theavailability or allocation of resources to the gas-exchangeprocess. Key words: A/Ci curve, CO2 assimilation, internal CO2 partial pressure, photosynthesis 相似文献
9.
Limitations to net photosynthesis as affected by nitrogen status in jack pine (Pinus banksiana Lamb.) seedlings 总被引:2,自引:0,他引:2
Relative limitations of nitrogen (N) status on the processescontributing to photosynthetic rate (A) were investigated. Jackpine {Pinus banksiana Lamb.) seedlings from seeds grown in sandculture were supplied with four different N treatments for 6weeks, which resulted in a needle N content ranging from 5085mmol m2 (1432 mg g1 dry weight). Leaf gasexchange at varying CO2 levels was measured and limitationson A350 (A at ambient CO2 level) caused by finite, limitingcarboxylation efficiency (c.e.), maximum A (Amax)and stomatalconductance were estimated from an analysis of the responseof A to internal CO2 concentration. Although c.e. and Amax decreasedlinearly with the decline in needle N, the magnitudes of theirchanges relative to A350 differed. Amax varied with A350 andalways exceeded A350 by 3738% c.e., however, declinedfaster than A350, as needle N level decreased. Consequently,relative limitation on A350 caused by inefficient Amax remainedconstant, but limitations caused by c.e. increased by 1015%at low N levels. In contrast, the limitation by stomatal conductancedeclined initially, but remained stable when N content droppedbelow 75 mmol m2. The results suggest: (1) a decreasein biochemical capacity, but not stomatal conductance, contributedto the reduction of A350 induced by N-deficiency in jack pineseedlings; and (2) the capacity of carboxylation appeared tobe impaired more than that of electron transport and/or photophosphorylationand its reduction may be the major reason for the reductionin A350. Key words: ACi analysis, carboxylation efficiency, electron transport, nitrogen deficiency, stomatal conductance 相似文献
10.
Effects of elevated carbon dioxide on three grass species from montane pasture II. Nutrient uptake, allocation and efficiency of use 总被引:5,自引:0,他引:5
Baxter R.; Gantley M.; Ashenden T.W.; Farrar J.F. 《Journal of experimental botany》1994,45(9):1267-1278
Agrostis capillaris L.4 Festuca vivipara L. and Poa alpinaL.were grown in outdoor open-top chambers at either ambient (340µmol mol1) or elevated (680 µmol1)CO2 for periods from 79 to 189 d. Under these conditions thereis increased growth of A. caplllarls and P. alpina, but reducedgrowth of F. vivipara. Nutrient use efficiency, nutrient productivity(total plant dry weight gain per unit of nutrient) and nutrientallocation of all three grass species were measured in an attemptto understand their individual growth responses further andto determine whether altered nutrient-use efficiencies and productivitiesenable plants exposed to an elevated atmospheric CO2 environmentto overcome potential limitations to growth imposed by soilfertility. Total uptake of nutrients was, in general, greater in plantsof A. capillaris and P. alpina (with the exception of N andK in the latter) when grown at 680 µmol mol1 CO2.In F. vivipara, however, uptake was considerably reduced inplants grown at the higher CO2 concentration. Overall, a doubling of atmospheric CO2 concentration had littleeffect on the nutrient use efficiency or productivity of A.capillaris. Reductions in tissue nutrient content resulted fromincreased plant growth and not altered nutrient use efficiency.In P. alpina, potassium, magnesium and calcium productivitieswere significantly reduced and photosynthetic nitrogen and phosphorususe efficiencies were doubled at elevated CO2 with respect toplants grown at ambient CO2 F. vivipara grown for 189 d showedthe most marked changes in nutrient use efficiency and nutrientproductivity (on an extracted dry weight basis) when grown atelevated CO2, F. vivipara grown at elevated CO2 however, showedlarge increases in the ratio of non-structural carbohydrateto nitrogen content of leaves and reproductive tissues, indicatinga substantial imbalance between the production and utilizationof assimilate. Key words: Nutrient, allocation, nutrient use efficiency, grasses, nutrient productivity, elevated CO2, cliniate change 相似文献
11.
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
12.
Fragments of maize leaves were incubated at controlled temperatureand irradiance either on distilled water or on one of threeconcentrations of cytokinin (101, 102 and 103mol m3). The effects of zeatin or kinetin on stomatalaperture were determined by stripping abaxial epidermis fromthe fragments after incubation and immediately measuring stomatalapertures under the microscope. At each cytokinin concentrationleaf pieces were incubated at 5 or 350 µmol mol1CO2 with or without ABA (101 mol m3). At 5.0 µmolmol1 CO2 increasing the concentrations of zeatin hada negligible effect upon stomatal aperture. When air containing350 umol mol1 CO2 was bubbled through the incubationsolutions, apertures of stomata incubated on water were morethan halved. Increasing cytokinin concentrations reduced theeffect of CO2 on stomata and incubation on 101 mol m3zeatin completely removed any CO2 response. The addition ofABA restored the effect of CO2, even at the highest cytokininconcentration. Key words: Maize, CO2 response, ABA, Cytokinins 相似文献
13.
Effects of Prolonged Darkness on the Sensitivity of Leaf Respiration to Carbon Dioxide Concentration in C3and C4Species 总被引:3,自引:1,他引:2
Predicting responses of plant and global carbon balance to theincreasing concentration of carbon dioxide in the atmosphererequires an understanding of the response of plant respirationto carbon dioxide concentration ([CO2]). Direct effects of thecarbon dioxide concentration at which rates of respiration ofplant tissue are measured are quite variable and their effectsremain controversial. One possible source of variation in responsivenessis the energy status of the tissue, which could influence thecontrol coefficients of enzymes, such as cytochrome-c oxidase,whose activity is sensitive to [CO2]. In this study we comparedresponses of respiration rate to [CO2] over the range of 60to 1000 µmol mol-1in fully expanded leaves of four C3andfour C4herbaceous species. Responses were measured near themiddle of the normal 10 h dark period, and also after another24 h of darkness. On average, rates of respiration were reducedabout 70% by the prolonged dark period, and leaf dry mass perunit area decreased about 30%. In all species studied, the relativedecrease in respiration rate with increasing [CO2] was largerafter prolonged darkness. In the C3species, rates measured at1000 µmol mol-1CO2averaged 0.89 of those measured at 60µmol mol-1in the middle of the normal dark period, and0.70-times when measured after prolonged darkness. In the C4species,rates measured at 1000 µmol mol-1CO2averaged 0.79 of thoseat 60 µmol mol-1CO2in the middle of the normal dark period,and 0.51-times when measured after prolonged darkness. In threeof the C3species and one of the C4species, the decrease in theabsolute respiration rate between 60 and 1000 µmol mol-1CO2wasessentially the same in the middle of the normal night periodand after prolonged darkness. In the other species, the decreasein the absolute rate of respiration with increase in [CO2] wassubstantially less after prolonged darkness than in the middleof the normal night period. These results indicated that increasingthe [CO2] at the time of measurement decreased respiration inall species examined, and that this effect was relatively largerin tissues in which the respiration rate was substrate-limited.The larger relative effect of [CO2] on respiration in tissuesafter prolonged darkness is evidence against a controlling roleof cytochrome-c oxidase in the direct effects of [CO2] on respiration.Copyright 2001 Annals of Botany Company Carbon dioxide, respiration, Abutilon theophrasti(L.), Amaranthus retroflexus(L.),Amaranthus hypochondriacus (L.), Datura stramonium(L.), Helianthus annuus(L.), Solanum melongena(L.), Sorghum bicolor(L. Moench), Zea mays 相似文献
14.
Polley H. Wayne; Johnson Hyrum B.; Mayeux Herman S.; Malone Stephen R. 《Annals of botany》1993,71(4):347-356
Two cultivars of wheat (Triticum aestivum L.), 'Yaqui 54' and'Seri M82', were grown along a gradient of daytime carbon dioxideconcentrations ([CO2]) from near 350-200 µmol CO2 mol-1air in a 38 m long controlled environment chamber. Carbon dioxidefluxes and evapotranspiration were measured for stands (plantsand soil) in five consecutive 7·6-m lengths of the chamberto determined potential effects of the glacial/interglacialincrease in atmospheric [CO2] on C3 plants. Growth rates andleaf areas of individual plants and net assimilation per unitleaf area and daily (24-h) net CO2 accumulation of wheat standsrose with increasing [CO2]. Daytime net assimilation (PD, mmolCO2 m-2 soil surface area) and water use efficiency of wheatstands increased and the daily total of photosynthetic photonflux density required by stands for positive CO2 accumulation(light compensation point) declined at higher [CO2]. Nighttimerespiration (RN, mmol CO2 m-2 soil surface) of wheat, measuredat 369-397 µmol mol-1 CO2, apparently was not alteredby growth at different daytime [CO2], but RN /PD of stands declinedlinearly as daytime [CO2] and PD increased. The responses ofwheat to [CO2], if representative of other C3 species, suggestthat the 75-100% increase in [CO2] since glaciation and the30% increase since 1800 reduced the minimum light and waterrequirements for growth and increased the productivity of C3plants.Copyright 1993, 1999 Academic Press Atmospheric carbon dioxide, carbon accumulation, evapotranspiration, light compensation point, net assimilation, respiration, Triticum aestivum, water use efficiency, wheat 相似文献
15.
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
16.
Mistletoes usually have slower rates of photosynthesis thantheir hosts. This study examines CO2assimilation, chlorophyllfluorescence and the chlorophyll content of temperate hostparasitepairs (nine hosts parasitized by Ileostylus micranthus and Carpodetusserratus parasitized by Tupeia antarctica). The hosts of I.micranthus had higher mean annual CO2assimilation (3.59 ±0.41 µmol m-2 s-1) than I. micranthus(2.42 ± 0.20µmol m-2 s-1), and C. serratus(2.41 ± 0.43 µmolm-2 s-1) showed higher CO2assimilation than T. antarctica(0.67± 0.64 µmol m-2 s-1). Hosts saturated at significantlyhigher electron transport rates (ETR) and light levels thanmistletoes. The positive relationship between CO2assimilationand electron transport suggests that the lower CO2assimilationrates in mistletoes are a consequence of lower electron transportrates. When photosynthetic rates, ETR and chlorophyll a /b ratioswere adjusted for photosynthetically active radiation, hostsdid not have significantly higher CO2assimilation (3.21 ±0.37 µmol m-2 s-1) than mistletoes (2.54 ± 0.41µmol m-2 s-1), but still had significantly higher ETRand chlorophyll a / b ratios. The electron transport rates,saturating light and chlorophyll a / b ratios of sun leavesfrom mistletoes were similar to host shade leaves. These responsesindicate that in comparison with their hosts, mistletoe leaveshave the photosynthetic characteristics of the leaves of shadeplants. Copyright 2000 Annals of Botany Company CO2assimilation, photosynthetic active radiation (PAR), chlorophyll fluorescence, electron transport rate (ETR), photochemical quenching (qp), non-photochemical quenching (qn), sun and shade leaves, chlorophyll content, Ileostylus micranthus, Tupeia antarctica, New Zealand 相似文献
17.
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
18.
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
19.
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
20.
Hogan K.P.; Fleck I.; Bungard R.; Cheeseman J.M.; Whitehead D. 《Journal of experimental botany》1997,48(6):1289-1297
Red beech (Nothofagus fusca (Hook. F.) Oerst.; Fagaceae) andradiata pine (Pinus radiata D. Don; Pinaceae) were grown for16 months in large open-top chambers at ambient (37 Pa) andelevated (66 Pa) atmospheric partial pressure of CO2, and incontrol plots (no chamber). Summer-time measurements showedthat photosynthetic capacity was similar at elevated CO2 (lightand CO2-saturated value of 17.2 µmol m2 s1for beech, 13.5 µmol m2 s1 for pine), plantsgrown at ambient CO2 (beech 21.0 µmol2 s1,pine 14.9 µmol m2s1) or control plants grownwithout chambers (beech 23.2 µmol m2 s1,pine 12.9 µmol m2 s1). However, the higherCO2 partial pressure had a direct effect on photosynthetic rate,such that under their respective growth conditions, photosynthesisfor the elevated CO2 treatment (measured at 70 Pa CO2 partialpressure: beech 14.1 µmol m2 s1 pine 10.3)was greater than in ambient (measured at 35 Pa CO2: beech 9.7µmol m2 s1, pine 7.0 µmol m2s1) or control plants (beech 10.8 µmol m2s1, pine 7.2 µmol m2 s1). Measurementsof chlorophyll fluorescence revealed no evidence of photodamagein any treatment for either species. The quantity of the photoprotectivexanthophyll cycle pigments and their degree of de-epoxidationat midday did not differ among treatments for either species.The photochemical efficiency of photosystem II (yield) was lowerin control plants than in chamber-grown plants, and was higherin chamber plants at ambient than at elevated CO2. These resultssuggest that at lower (ambient) CO2 partial pressure, beechplants may have dissipated excess energy by a mechanism thatdoes not involve the xanthophyll cycle pigments. Key words: Carotenoids, chlorophyll fluorescence, photosynthesis, photoinhibition, photoprotection, xanthophyll cycle 相似文献