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1.
Improved method for measuring the apparent CO2 photocompensation point resolves the impact of multiple internal conductances to CO2 to net gas exchange
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There is a growing interest in accurate and comparable measurements of the CO2 photocompensation point (Γ*), a vital parameter to model leaf photosynthesis. The Γ* is measured as the common intersection of several CO2 response curves, but this method may incorrectly estimate Γ* by using linear fits to extrapolate curvilinear responses and single conductances to convert intercellular photocompensation points (Ci*) to chloroplastic Γ*. To determine the magnitude and minimize the impact of these artefacts on Γ* determinations, we used a combination of meta‐analysis, modelling and original measurements to develop a framework to accurately determine Ci*. Our modelling indicated that the impact of using linear fits could be minimized based on the measurement CO2 range. We also propose a novel method of analysing common intersection measurements using slope–intercept regression. Our modelling indicated that slope–intercept regression is a robust analytical tool that can help determine if a measurement is biased because of multiple internal conductances to CO2. Application of slope–intercept regression to Nicotiana tabacum and Glycine max revealed that multiple conductances likely have little impact to Ci* measurements in these species. These findings present a robust and easy to apply protocol to help resolve key questions concerning CO2 conductance through leaves. 相似文献
2.
The relationship between CO2 exchange and relative electron-transport rate through photosystem II (ETR, measured using chlorophyll a fluorescence) was determined for a moss and a green algal lichen, photobiont probably Trebouxia sp., in the field in Antarctica. Net photosynthesis (NP) and dark respiration (DR) were measured over temperatures from zero
to 25 °C and gross photosynthesis (GP) calculated (GP = NP + DR). The strong response of DR to temperature in these organisms
resulted in substantial changes in CO2 exchange rates. The moss Bryum argenteum Hedw. showed a strong, linear relationship between GP and ETR. This was an unexpected result since mosses are C3 plants and, in higher plants, this group normally has a curvilinear GP versus ETR relationship. It is suggested that suppression
of DR in the light might be involved. The lichen, Umbilicaria aprina Nyl., had nonlinear relationships between ETR and GP that were different at each measurement temperature. In some cases the
lowest ETR was at the higher CO2 exchange rates. It is suggested that these relationships are the result of strong quenching mechanisms that are inversely
proportional to GP. The results support a growing impression that the relationships between ETR and CO2 exchange are complex in these organisms and different from those found for higher plants.
Received: 24 November 1997 / Accepted 2 May 1998 相似文献
3.
Contribution of benthic microalgae to the temporal variation in phytoplankton assemblages in a macrotidal system
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Tania Hernández Fariñas Lourenço Ribeiro Dominique Soudant Catherine Belin Cédric Bacher Luis Lampert Laurent Barillé 《Journal of phycology》2017,53(5):1020-1034
Suspended marine benthic microalgae in the water column reflect the close relationship between the benthic and pelagic components of coastal ecosystems. In this study, a 12‐year phytoplankton time‐series was used to investigate the contribution of benthic microalgae to the pelagic system at a site along the French‐Atlantic coast. Furthermore, all taxa identified were allocated into different growth forms in order to study their seasonal patterns. The highest contribution of benthic microalgae was observed during the winter period, reaching up to 60% of the carbon biomass in the water column. The haptobenthic growth form showed the highest contribution in terms of biomass, dominant in the fall‐winter period when the turbidity and the river flow were high. The epipelic growth form did not follow any seasonal pattern. The epiphytic diatom Licmophora was most commonly found during summer. As benthic microalgae were found in the water column throughout the year, the temporal variation detected in the structure of pelagic assemblages in a macrotidal ecosystem was partly derived from the differentiated contribution of several benthic growth forms. 相似文献
4.
Juliet Brodie Christopher J. Williamson Dan A. Smale Nicholas A. Kamenos Nova Mieszkowska Rui Santos Michael Cunliffe Michael Steinke Christopher Yesson Kathryn M. Anderson Valentina Asnaghi Colin Brownlee Heidi L. Burdett Michael T. Burrows Sinead Collins Penelope J. C. Donohue Ben Harvey Andrew Foggo Fanny Noisette Joana Nunes Federica Ragazzola John A. Raven Daniela N. Schmidt David Suggett Mirta Teichberg Jason M. Hall‐Spencer 《Ecology and evolution》2014,4(13):2787-2798
Seaweed and seagrass communities in the northeast Atlantic have been profoundly impacted by humans, and the rate of change is accelerating rapidly due to runaway CO2 emissions and mounting pressures on coastlines associated with human population growth and increased consumption of finite resources. Here, we predict how rapid warming and acidification are likely to affect benthic flora and coastal ecosystems of the northeast Atlantic in this century, based on global evidence from the literature as interpreted by the collective knowledge of the authorship. We predict that warming will kill off kelp forests in the south and that ocean acidification will remove maerl habitat in the north. Seagrasses will proliferate, and associated epiphytes switch from calcified algae to diatoms and filamentous species. Invasive species will thrive in niches liberated by loss of native species and spread via exponential development of artificial marine structures. Combined impacts of seawater warming, ocean acidification, and increased storminess may replace structurally diverse seaweed canopies, with associated calcified and noncalcified flora, with simple habitats dominated by noncalcified, turf‐forming seaweeds. 相似文献
5.
N. S. Balaur V. A. Vorontsov E. I. Kleiman Yu. D. Ton 《Russian Journal of Plant Physiology》2009,56(3):423-427
A novel technique designed for component monitoring of CO2 exchange in plants is described. The system is based on application of self-clamping leaf chambers connected to an open gas-exchange measuring system and on automatic recording of CO2 concentration. This technique was implemented in a commercially available instrument, PTM-48A Photosynthesis Monitor, which provides for long-term measurements of gas exchange and for discrimination of its separate components. Furthermore, many other plant functions can be monitored during plant growth and development under laboratory, greenhouse, and field conditions. 相似文献
6.
Leaf gas exchange of beech (Fagus sylvatica L.) seedlings in lightflecks: A system for measuring rapid changes in CO2 partial pressures 总被引:1,自引:0,他引:1
A system is described for the measurement of fast transient responses of leaf gas exchange to lightflecks. Any chamber adulterates a true signal unless in the steady-state; therefore, a procedure for estimating an effective chamber volume is presented which is an essential parameter for correcting a measured transient signal. A common correction is critically commented on. With the system, responses of net photosynthesis to lightflecks as short as 1 s have been observed in leaves of seedlings of Fagus sylvatica L. 相似文献
7.
Acclimation of photosynthesis to increasing atmospheric CO2: The gas exchange perspective 总被引:9,自引:0,他引:9
Rowan F. Sage 《Photosynthesis research》1994,39(3):351-368
The nature of photosynthetic acclimation to elevated CO2 is evaluated from the results of over 40 studies focusing on the effect of long-term CO2 enrichment on the short-term response of photosynthesis to intercellular CO2 (the A/Ci response). The effect of CO2 enrichment on the A/Ci response was dependent on growth conditions, with plants grown in small pots (< 5 L) or low nutrients usually exhibiting a reduction of A at a given Ci, while plants grown without nutrient deficiency in large pots or in the field tended to exhibit either little reduction or an enhancement of A at a given Ci following a doubling or tripling of atmospheric CO2 during growth. Using theoretical interpretations of A/Ci curves to assess acclimation, it was found that when pot size or nutrient deficiency was not a factor, changes in the shape of A/Ci curves which are indicative of a reallocation of resources within the photosynthetic apparatus typically were not observed. Long-term CO2 enrichment usually had little effect or increased the value of A at all Ci. However, a minority of species grown at elevated CO2 exhibited gas exchange responses indicative of a reduced amount of Rubisco and an enhanced capacity to metabolize photosynthetic products. This type of response was considered beneficial because it enhanced both photosynthetic capacity at high CO2 and reduced resource investment in excessive Rubisco capacity. The ratio of intercellular to ambient CO2 (the Ci/Ca ratio) was used to evaluate stomatal acclimation. Except under water and humidity stress, Ci/Ca exhibited no consistent change in a variety of C3 species, indicating no stomatal acclimation. Under drought or humidity stress, Ci/Ca declined in high-CO2 grown plants, indicating stomata will become more conservative during stress episodes in future high CO2 environments.Abbreviations A
net CO2 assimilation rate
- Ci (Ca)
intercellular (ambient) partial pressure of CO2
- operational Ci
intercellular partial pressure of CO2 at a given ambient partial pressure of CO2
- gs
stomatal conductance
- normal CO2
current atmospheric mole fraction of CO2 (330 to 355 mol mol–1)
- Rubisco
ribulose-1,5-bisphosphate carboxylase/oxygenase 相似文献
8.
Important gas exchange characteristics of C4 plants depend on the properties of phophoenolpyruvate carboxylase (PEPC), the enzyme catalysing the primary fixation of CO2 during C4 photosynthesis. In this study, the relationship between intracellular resistance for CO2 fixation (ri) at high photosynthetically active photon flux densities (PPFD) and maximum PEPC activity in vitro (Vpm) was examined in leaves of Zea mays L. The analysis allowed the estimation of the Michaelis constant Kp of the enzyme for CO2 (or the equivalent number for bicarbonate) in vivo. At low PPFD (below 100 mol m-2 s-1) the initial slopes of the curves describing net CO2 uptake rate A as a function of intercellular CO2 concentration ci increased with increasing PPFD. The increase (i. e. a decrease in ri) was interpreted as due to a reversible activation of PEPC by light. Including this assumption into a model of C4 photosynthesis enabled us to reproduce A(ci) response curves measured at low levels of PPFD. Fitting the model to experimental data resulted in values for KI, the PPFD at which PEPC reaches half of its full activation, of about 200 mol m-2 s-1. Similar results were derived from the dependence of ri on PPFD. The analysis of the relationships between ri and Vpm and between ri and PPFD, as well as fitting of the model to gas exchange data all gave rise to estimates for the resistance for CO2 transfer within mesophyll cells that are comparable with those known from C3 plants. 相似文献
9.
Rapid light-response curves (RLC) of variable chlorophyll fluorescence were measured on estuarine benthic microalgae with
the purpose of characterising its response to changes in ambient light, and of investigating the relationship to steady-state
light-response curves (LC). The response of RLCs to changes in ambient light (E, defined as the irradiance level to which a sample is acclimated to prior to the start of the RLC) was characterised by constructing
light-response curves for the RLC parameters α
RLC, the initial slope, ETRm,RLC, the maximum relative electron transport rate, and E
k,RLC, the light-saturation parameter. Measurements were carried out on diatom-dominated suspensions of benthic microalgae and
RLC and LC parameters were compared for a wide range of ambient light conditions, time of day, season and sample taxonomic
composition. The photoresponse of RLC parameters was typically bi-phasic, consisting of an initial increase of all parameters
under low ambient light (E < 21–181 μmol m−2 s−1), and of a phase during which α
RLC decreased significantly with E, and the increase of ETRm,RLC and E
k,RLC was attenuated. The relationship between RLC and LC parameters was dependent on ambient irradiance, with significant correlations
being found between α
RLC and α, and between ETRm,RLC and ETRm, for samples acclimated to low and to high ambient irradiances, respectively. The decline of α
RLC under high light (Δα
RLC) was strongly correlated (P < 0.001 in all cases) with the level of non-photochemical quenching (NPQ) measured before each RLC. These results indicate
the possibility of using RLCs to characterise the steady-state photoacclimation status of a sample, by estimating the LC parameter
E
k, and to trace short-term changes in NPQ levels without dark incubation. 相似文献
10.
Junbin Zhao Matthias Peichl Mats Öquist Mats B. Nilsson 《Global Change Biology》2016,22(12):4028-4037
In high‐latitude regions, carbon dioxide (CO2) emissions during the winter represent an important component of the annual ecosystem carbon budget; however, the mechanisms that control the winter CO2 emissions are currently not well understood. It has been suggested that substrate availability from soil labile carbon pools is a main driver of winter CO2 emissions. In ecosystems that are dominated by annual herbaceous plants, much of the biomass produced during the summer is likely to contribute to the soil labile carbon pool through litter fall and root senescence in the autumn. Thus, the summer carbon uptake in the ecosystem may have a significant influence on the subsequent winter CO2 emissions. To test this hypothesis, we conducted a plot‐scale shading experiment in a boreal peatland to reduce the gross primary production (GPP) during the growing season. At the growing season peak, vascular plant biomass in the shaded plots was half that in the control plots. During the subsequent winter, the mean CO2 emission rates were 21% lower in the shaded plots than in the control plots. In addition, long‐term (2001–2012) eddy covariance data from the same site showed a strong correlation between the GPP (particularly the late summer and autumn GPP) and the subsequent winter net ecosystem CO2 exchange (NEE). In contrast, abiotic factors during the winter could not explain the interannual variation in the cumulative winter NEE. Our study demonstrates the presence of a cross‐seasonal link between the growing season biotic processes and winter CO2 emissions, which has important implications for predicting winter CO2 emission dynamics in response to future climate change. 相似文献
11.
12.
ANTTI KILPELÄINEN ASHRAFUL ALAM HARRI STRANDMAN SEPPO KELLOMÄKI 《Global Change Biology Bioenergy》2011,3(6):461-471
The study describes an integrated impact assessment tool for the net carbon dioxide (CO2) exchange in forest production. The components of the net carbon exchange include the uptake of carbon into biomass, the decomposition of litter and humus, emissions from forest management operations and carbon released from the combustion of biomass and degradation of wood‐based products. The tool enables the allocation of the total carbon emissions to the timber and energy biomass and to the energy produced on the basis of biomass. In example computations, ecosystem model simulations were utilized as an input to the tool. We present results for traditional timber production (pulpwood and saw logs) and integrated timber and bioenergy production (logging residues, stumps and roots) for Norway spruce, in boreal conditions in Finland, with two climate scenarios over one rotation period. The results showed that the magnitude of management related emissions on net carbon exchange was smaller when compared with the total ecosystem fluxes; decomposition being the largest emission contributor. In addition, the effects of management and climate were higher on the decomposition of new humus compared with old humus. The results also showed that probable increased biomass growth, obtained under the changing climate (CC), could not compensate for decomposition and biomass combustion related carbon loss in southern Finland. In our examples, the emissions allocated for the energy from biomass in southern Finland were 172 and 188 kg CO2 MW h?1 in the current climate and in a CC, respectively, and 199 and 157 kg CO2 MW h?1 in northern Finland. This study concludes that the tool is suitable for estimating the net carbon exchange of forest production. The tool also enables the allocation of direct and indirect carbon emissions, related to forest production over its life cycle, in different environmental conditions and for alternative time periods and land uses. Simulations of forest management regimes together with the CC give new insights into ecologically sustainable forest bioenergy and timber production, as well as climate change mitigation options in boreal forests. 相似文献
13.
Light adaptation and photosynthetic productivity were studied in common reef-building corals on islands of the Indian Ocean and the South China Sea. When light is attenuated, both in shade and at depth, adaptations by zooxanthellae permit maximal absorption and utilization of light. Better utilization of incident light in shade-dwelling and deep-water coral forms is reflected by higher values of gross photosynthesis on the plateau and linear portion of the photosynthesis-irradiance curve. It was shown that outer branches of reef-building corals are autotrophic in a major part of their light-range distribution and have a high and stable level of primary production. 相似文献
14.
应用植物光合作用对光响应修正模型研究了CO2浓度分别为380和600 mol·mol-1时,栾树和辣椒在光补偿点附近光合量子效率的改变及Kok效应。结果表明:光响应修正模型可很好地拟合栾树和辣椒2种CO2浓度下的光响应曲线,且获得的光合参数与实测值相符合;2种不同CO2浓度条件下,栾树和辣椒总是存在初始量子效率(φ0)大于光补偿点处的量子效率(φc),光合量子效率在光补偿点附近不是常数,且与暗呼吸速率无关;CO2浓度的大小影响着栾树的Kok效应,但对辣椒的Kok效应影响不明显,分析认为,这是由于栾树在光补偿点附近光合量子效率的改变来自其净光合速率对光强的非线性响应,而辣椒不存在Kok效应。 相似文献
15.
A 13C/12C mass spectrometer was interfaced with a open gas exchange system including four growth chambers to investigate CO2 exchange components of perennial ryegrass (Lolium perenne L.) stands. Chambers were fed with air containing CO2 with known δ13C (δCΟ2?2.6 or ?46.8‰). The system did not fractionate C isotopes and no extraneous CO2 leaked into chambers. The on‐line 13C discrimination (Δ) of ryegrass stands in light was independent of δCΟ2 when δCΟ2 was constant. The δ of CO2 exchanged by the stands in light (δNd) and darkness (δRn) differed by 0.7‰, suggesting some Δ in dark respiration at the stand‐level. However, Δ decreased by ~ 10‰ when δCΟ2 was switched from ?46.8 to ?2.5‰, and increased by ~ 10‰ following a shift from ?2.6 to ?46.7‰ due to isotopic disequilibria between photosynthetic and respiratory fluxes. Isotopic imbalances were used to assess (non‐photorespiratory) respiration in light and the replacement of the respiratory substrate pool(s) by new photosynthate. Respiration was partially inhibited by light, but increased during the light period and decreased in darkness, in association with temperature changes. The labelling kinetics of respiratory CO2 indicated the existence of two major respiratory substrate pools: a fast pool which was exchanged within hours, and a slow pool accounting for ~ 60% of total respiration and having a mean residence time of 3.6 d. 相似文献
16.
Cummings B Hamilton ML Ciaffoni L Pragnell TR Peverall R Ritchie GA Hancock G Robbins PA 《Journal of applied physiology (Bethesda, Md. : 1985)》2011,111(1):303-307
The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations. 相似文献
17.
Annual patterns of phytoplankton density and primary production in a large, shallow lake: the central role of light 总被引:2,自引:0,他引:2
A. TORREMORELL M. E. LLAMES G. L. PÉREZ R. ESCARAY J. BUSTINGORRY H. ZAGARESE 《Freshwater Biology》2009,54(3):437-449
1. We studied the seasonal dynamics of suspended particulate matter in a turbid, large shallow lake during an annual period (2005–06). We relate the patterns of seston concentration (total suspended solids), phytoplankton biomass and water transparency to the seasonal pattern of incident solar radiation (I0). We also report the seasonal trends of phytoplankton primary production (PP) and photosynthesis photoinhibition due to photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) (Iβ and UV50). 2. We first collected empirical evidence that indicated the conditions of light limitation persisted during the study period. We found that the depth‐averaged irradiance estimated for the time of the day of maximum irradiance (Imean–noon) was always lower than the measured onset of light saturation of photosynthesis (Ik). 3. We then contrasted the observations with theoretical expectations based on a light limitation scenario. The observed temporal patterns of seston concentration, both on a volume and area basis, were significantly explained by I0 (R2 = 0.39 and R2 = 0.37 respectively). The vertical diffuse attenuation coefficient (kdPAR) (R2 = 0.55) and the depth‐averaged irradiance (Imean) (R2 = 0.66), significantly increased with the I0; while the irradiance reaching the lake bottom (Iout) significantly decreased with the incident irradiance (R2 = 0.49). However, phytoplankton biovolume maxima were not coincident with the time of the year of maximum irradiance. 4. A significant positive relationship was observed between PP estimated on an area basis and I0 (R2 = 0.51, P < 0.001). In addition, the parameters describing the photosynthetic responses to high irradiances displayed marked seasonal trends. The photosynthesis photoinhibition due to PAR as well as to UV were significantly related to incident solar radiation (PAR: R2 = 0.73; UV: R2 = 0.74). These results suggest adaptation of the phytoplankton community in response to changes in incident solar radiation. 相似文献
18.
J. W. Cary 《Photosynthesis research》1981,2(3):185-194
A new theory and experimental method was developed to measure the diffusion resistance to CO2 in the gas phase of mesophyll leaf tissue. Excised leaves were placed in a chamber and their net evaporation and CO2 assimilation rates measured at two different ambient pressures. These data were used to calculate CO2 gas phase diffusion resistances. A variety of field grown leaves were tested and the effects of various experimental errors considered. Increasing the gas phase diffusion resistance decreased transpiration more than it decreased CO2 assimilation. It was concluded that gas phase diffusion resistance associated with CO2 assimilation may sometimes be 100 or 200 s·m-1 greater than the resistance implied by transpiration rates. This may be due to longer path lengths for the CO2 diffusion, constricted in places by the shape and arrangement of mesophyll cells. 相似文献
19.
Phosphate recycling under photorespiratory conditions was investigated using intact wheat chloroplasts from Triticum aestivum (cv. Maris dove). A decline in the optimal Pi level needed to support steady-state photosynthesis was observed (a) as the bicarbonate supply became limiting, or (b) as oxygen concentrations were increased. Further, at subsaturating CO2 and elevated O2 (52%), photosynthetic induction periods were shortest in the absence of exogenous Pi, and severely extended by its addition. Thus, photosynthesis under low CO2 levels which favor ribulose 1,5 bisphosphate (RuBP) oxygenase activity and glycolate synthesis by chloroplasts decreases their dependency on exogenous Pi from the initial illumination of chloroplasts through to the attainment of steady state rates of O2 evolution. Uptake of phosphate (Pi) was directly measured at ambient O2 concentrations and showed the stoichiometry of O2 evolved to Pi consumed at 10 mmol/L bicarbonate (saturating) had a mean value of 3.0, and was increased to 5.4 at 2.5 mmol/L bicarbonate and to > 8.0 at 1.0 mmol/L bicarbonate. The observation is consistent with enhanced stromal recycling of Pi released during hydrolysis of phosphoglycolate produced in greater quantities as the ratio of RuBP carboxylase relative to oxygenase activities (vc/vo) declines. The theoretical relationship between vc/vo and O2/Pi stoichiometries was derived and compared favorably to experimental data obtained. 相似文献
20.
Biomass production from macroalgae has been viewed as important mainly because of the need for pollution abatement. Environmental considerations will increasingly determine product and process acceptability and drive the next generation of economic opportunity. Some countries, including Japan, are actively promoting "green" technologies that will be in demand worldwide in the coming decades. Should an international agreement on CO2-reduction be ratified, its effective use for energy production would be of high priority. This report shows that macroalgae have great potential for biomass production and CO2 bioremediation. Macroalgae have high productivity, as great or greater than the most productive land plants, and do not compete with terrestrial crops for farm land. The review focuses on recent data on productivity, photosynthesis, nutrient dynamics, optimization and economics. Biomass from macroalgae promises to provide environmentally and economically feasible alternatives to fossil fuels. Nevertheless, the techniques and technologies for growing macroalgae on a large-scale and for converting feedstocks to energy carriers must be more fully developed. 相似文献