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1.
Yosuke Okimoto Akihiro Nose Keizo Ikeda Sakae Agarie Kenzo Oshima Yutaka Tateda Takashi Ishii Dang D. Nhan 《Wetlands Ecology and Management》2008,16(2):155-171
In many coastal areas of South-East Asia, attempts have been made to revive coastal ecosystem by initiating projects that
encourage planting of mangrove trees. Compared to the terrestrial trees, mangrove trees possess a higher carbon fixation capacity.
It becomes a very significant option for clean development mechanism (CDM) program. However, a reliable method to estimate
CO2 fixation capacity of mangrove trees has not been established. Acknowledging the above fact, we decided to set up an estimation
method for the CDM program, using gas exchange analysis to estimate mangrove productivity, we put into consideration the net
CO2 fixation of reforested Kandelia candel (5-, 10-, and 15-year-old stand). This was estimated by gas exchange analysis and growth curve analysis. In growth curve
analysis, we drew a growth curve of a single stand using data of above- and below-ground biomass. In the gas exchange analysis,
we calculated CO2 fixation capacity by (1) measuring respiration rate of each organ of stand and calculating respiratory CO2 emission from above- to below-ground biomass. (2) Measuring the single-leaf photosynthetic rate in response to light intensity
and calculating the photosynthetic CO2 absorption. (3) We also developed a model for the diurnal changes in temperature, and monthly averages based on one-day estimation
of CO2 absorption and emission, which we corrected by this model in order to estimate the net CO2 fixation capacity in response to temperature. Comparing the biomass accumulation of the two methods constructed for the same
forest, the above-ground biomass accumulation of 10-year-old forest (34.3 ton ha−1 yr−1) estimated by gas exchange analysis was closely compared to those of growth curve analysis (26.6 ton ha−1 yr−1), suggesting that the gas exchange analysis was capable of estimating mangrove productivity. The validity of the estimated
CO2 fixation capacity by the gas exchange analysis and the growth curve analysis was also discussed. 相似文献
2.
Our research objectives are to determine under what conditions microalgal-based CO2 capture from flue gases is economically attractive. Specifically, our objective here was to select microalgae that are temperature,
pH and flue gas tolerant. Microalgae were grown under five different temperatures, three different pH and five different flue
gas mixtures besides 100% CO2 (gas concentrations that the cells were exposed to ranged 5.7–100% CO2, 0–3504 ppm SO2, 0–328 ppm NO, and 0–126 ppm NO2). Our results indicate that the microalgal strains tested exhibit a substantial ability to withstand a wide range of temperature
(54 strains tested), pH (20 strains tested) and flue gas composition (24 strains tested) likely to be encountered in cultures
used for carbon sequestration from smoke stack gases. Our results indicate that microalgal photosynthesis is a limited but
viable strategy for CO2 capture from flue gases produced by stationary combustion sources. 相似文献
3.
We describe the long-term effects of a CO2 exhalation, created more than 70 years ago, on a natural C4 dominated sub-tropical grassland in terms of ecosystem structure and functioning. We tested whether long-term CO2 enrichment changes the competitive balance between plants with C3 and C4 photosynthetic pathways and how CO2 enrichment has affected species composition, plant growth responses, leaf properties and soil nutrient, carbon and water dynamics. Long-term effects of elevated CO2 on plant community composition and system processes in this sub-tropical grassland indicate very subtle changes in ecosystem functioning and no changes in species composition and dominance which could be ascribed to elevated CO2 alone. Species compositional data and soil δ13C isotopic evidence suggest no detectable effect of CO2 enrichment on C3:C4 plant mixtures and individual species dominance. Contrary to many general predictions C3 grasses did not become more abundant and C3 shrubs and trees did not invade the site. No season length stimulation of plant growth was found even after 5 years of exposure to CO2 concentrations averaging 610 μmol mol−1. Leaf properties such as total N decreased in the C3 but not C4 grass under elevated CO2 while total non-structural carbohydrate accumulation was not affected. Elevated CO2 possibly lead to increased end-of-season soil water contents and this result agrees with earlier studies despite the topographic water gradient being a confounding problem at our research site. Long-term CO2 enrichment also had little effect on soil carbon storage with no detectable changes in soil organic matter found. There were indications that potential soil respiration and N mineralization rates could be higher in soils close to the CO2 source. The conservative response of this grassland suggests that many of the reported effects of elevated CO2 on similar ecosystems could be short duration experimental artefacts that disappear under long-term elevated CO2 conditions. 相似文献
4.
In the quest for renewable resources, algae are increasingly receiving attention. Their high growth rate, high CO2 fixation and their lack of requirement for fertile soil surface represent several advantages as compared to conventional (energy) crops. Through their ability to store large amounts of oils, they qualify as a source for biodiesel. Algal biomass, however, can also be used as such, namely as a substrate for anaerobic digestion. In the present research, we investigated the use of algae for energy generation in a stand‐alone, closed‐loop system. The system encompasses an algal growth unit for biomass production, an anaerobic digestion unit to convert the biomass to biogas and a microbial fuel cell to polish the effluent of the digester. Nutrients set free during digestion can accordingly be returned to the algal growth unit for a sustained algal growth. Hence, a system is presented that continuously transforms solar energy into energy‐rich biogas and electricity. Algal productivities of 24–30 ton VS ha?1 year?1 were reached, while 0.5 N m3 biogas could be produced kg?1 algal VS. The system described resulted in a power plant with a potential capacity of about 9 kW ha?1 of solar algal panel, with prospects of 23 kW ha?1. Biotechnol. Bioeng. 2009;103: 296–304. © 2009 Wiley Periodicals, Inc. 相似文献
5.
Do short-term fluctuations in CO2 concentrations at elevated CO2 levels affect net CO2 uptake rates of plants? When exposed to 600 μl CO2 l?1, net CO2 uptake rates in shoots or leaves of seedlings of two tropical C3 tree species, teak (Tectona grandis L. f.) and barrigon [Pseudobombax septenatum (Jacq.) Dug.], increased by 28 and 52% respectively. In the presence of oscillations with half-cycles of 20 s, amplitude of ca. 170 μl CO2 l?1 and mean of 600 μl CO2 l?1, the stimulation in net CO2 uptake by the two species was reduced to 19 and 36%, respectively, i.e. the CO2 stimulation in photosynthesis associated with a change in exposure from 370 to 600 μl CO2 l?1 was reduced by a third in both species. Similar reductions in CO2-stimulated net CO2 uptake were observed in T. grandis exposed to 40-s oscillations. Rates of CO2 efflux in the dark by whole shoots of T. grandis decreased by 4.8% upon exposure of plants grown at 370 μl CO2 l?1 to 600 μl CO2 l?1. The potential implications of the observations on CO2 oscillations and dark respiration are discussed in the context of free-air CO2 enrichment (FACE) systems in which short-term fluctuations of CO2 concentration are a common feature. 相似文献
6.
Flue gas generated by combustion of natural gas in a boiler was used for outdoor cultivation of Chlorella sp. in a 55 m2 culture area photobioreactor. A 6 mm thick layer of algal suspension continuously running down the inclined lanes of the
bioreactor at 50 cm s−1 was exposed to sunlight. Flue gas containing 6–8% by volume of CO2 substituted for more costly pure CO2 as a source of carbon for autotrophic growth of algae. The degree of CO2 mitigation (flue gas decarbonization) in the algal suspension was 10–50% and decreased with increasing flue gas injection
rate into the culture. A dissolved CO2 partial pressure (pCO2) higher than 0.1 kPa was maintained in the suspension at the end of the 50 m long culture area in order to prevent limitation
of algal growth by CO2. NOX and CO gases (up to 45 mg m−3 NOX and 3 mg m−3 CO in flue gas) had no negative influence on the growth of the alga. On summer days the following daily net productivities
of algae [g (dry weight) m−2] were attained in comparative parallel cultures: flue gas = 19.4–22.8; pure CO2 = 19.1–22.6. Net utilization (η) of the photosynthetically active radiant (PAR) energy was: flue gas = 5.58–6.94%; pure CO2 = 5.49–6.88%. The mass balance of CO2 obtained for the flue gas stream and for the algal suspension was included in a mathematical model, which permitted the calculation
of optimum flue gas injection rate into the photobioreactor, dependent on the time course of irradiance and culture temperature.
It was estimated that about 50% of flue gas decarbonization can be attained in the photobioreactor and 4.4 kg of CO2 is needed for production of 1 kg (dry weight) algal biomass. A scheme of a combined process of farm unit size is proposed;
this includes anaerobic digestion of organic agricultural wastes, production and combustion of biogas, and utilization of
flue gas for production of microalgal biomass, which could be used in animal feeds. A preliminary quantitative assessment
of the microalgae production is presented. 相似文献
7.
人类活动造成大气二氧化碳(CO2)浓度不断升高,使当今世界面临着气候变化的重大危机。微生物CO2固定为实现地球“碳中和”提供了一条有前景的绿色发展路线。与自养微生物相比,异养微生物具有更快的生长速度和更先进的遗传工具,但是其固定CO2的能力还很有限。近年来,基于合成生物学技术强化异养微生物CO2固定受到诸多关注,主要包括优化能量供给、改造羧化途径以及基于异养微生物间接固定CO2。本综述将围绕上述3个方面重点讨论异养微生物CO2固定的研究进展,为将来更好地利用微生物CO2固定技术实现“碳达峰、碳中和”提供参考。 相似文献
8.
Activation of Rubisco controls CO<Subscript>2</Subscript> assimilation in light: a perspective on its discovery 总被引:2,自引:0,他引:2
Jensen R 《Photosynthesis research》2004,82(2):187-193
CO2 fixation during photosynthesis is regulated by the activity of ribulose bisphosphate carboxylase (Rubisco). This conclusion
became more apparent to me after CO2-fixation experiments using isolated spinach chloroplasts and protoplasts, purified Rubisco enzyme, and intact leaves. Ribulose
bisphosphate (RuBP) pools and activation of Rubisco were measured and compared to 14CO2 fixation in light. The rates of 14CO 2 assimilation best followed the changes in Rubisco activation under moderate to high light intensities. RuBP pool sizes regulated
14
2 assimilation only in very high CO2 levels, low light and in darkness. Activation of Rubisco involves two separate processes: carbamylation of the protein and
removal of inhibitors blocking carbamylation or blocking RuBP binding to carbamylated sites before reaction with CO2 or O2.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
The problem of climate change arising mainly from CO2 emission is currently a critical environmental issue. Biofixation using microalgae has recently become an attractive approach to CO2 capture and recycling with additional benefits of downstream utilization and applications of the resulting microalgal biomass. This review summarizes the history and strategies of microalgal mitigation of CO2 emissions, photobioreactor systems used to cultivate microalgae for CO2 fixation, current microalgae harvesting methods, as well as applications of valuable by-products. It is of importance to select appropriate microalgal species to achieve an efficient and economically feasible CO2-emission mitigation process. The desired microalgae species should have a high growth rate, high CO2 fixation ability, low contamination risk, low operation cost, be easy to harvest and rich in valuable components in their biomass. 相似文献
10.
Nedbal L Cervený J Keren N Kaplan A 《Journal of industrial microbiology & biotechnology》2010,37(12):1319-1326
Carbon dioxide (CO2) availability strongly affects the productivity of algal photobioreactors, where it is dynamically exchanged between different
compartments, phases, and chemical forms. To understand the underlying processes, we constructed a nonequilibrium mathematical
model of CO2 dynamics in a flat-panel algal photobioreactor. The model includes mass transfer to the algal suspension from a stream of
bubbles of CO2-enriched air and from the photobioreactor headspace. Also included are the hydration of dissolved CO2 to bicarbonate ion (HCO3−) as well as uptake and/or cycling of these two chemical forms by the cells. The model was validated in experiments using
a laboratory-scale flat-panel photobioreactor that controls light, temperature, and pH and where the concentration of dissolved
CO2, and partial pressure of CO2 in the photobioreactor exhaust are measured. First, the model prediction was compared with measured CO2 dynamics that occurred in response to a stepwise change in the CO2 partial pressure in the gas sparger. Furthermore, the model was used to predict CO2 dynamics in photobioreactors with unicellular, nitrogen-fixing cyanobacterium Cyanothece sp. The metabolism changes dramatically during a day, and the distribution of CO2 is expected to exhibit a pronounced diurnal modulation that significantly deviates from chemical equilibrium. 相似文献
11.
Edoardo Daly Sari Palmroth Paul Stoy Mario Siqueira A. Christopher Oishi Jehn-Yih Juang Ram Oren Amilcare Porporato Gabriel G. Katul 《Biogeochemistry》2009,94(3):271-287
Profiles of subsurface soil CO2 concentration, soil temperature, and soil moisture, and throughfall were measured continuously during the years 2005 and
2006 in 16 locations at the free air CO2 enrichment facility situated within a temperate loblolly pine (Pinus taeda L.) stand. Sampling at these locations followed a 4 by 4 replicated experimental design comprised of two atmospheric CO2 concentration levels (ambient [CO2]a, ambient + 200 ppmv, [CO2]e) and two soil nitrogen (N) deposition levels (ambient, ambient + fertilization at 11.2 gN m−2 year−1). The combination of these measurements permitted indirect estimation of belowground CO2 production and flux profiles in the mineral soil. Adjacent to the soil CO2 profiles, direct (chamber-based) measurements of CO2 fluxes from the soil–litter complex were simultaneously conducted using the automated carbon efflux system. Based on the
measured soil CO2 profiles, neither [CO2]e nor N fertilization had a statistically significant effect on seasonal soil CO2, CO2 production, and effluxes from the mineral soil over the study period. Soil moisture and temperature had different effects
on CO2 concentration depending on the depth. Variations in CO2 were mostly explained by soil temperature at deeper soil layers, while water content was an important driver at the surface
(within the first 10 cm), where CO2 pulses were induced by rainfall events. The soil effluxes were equal to the CO2 production for most of the time, suggesting that the site reached near steady-state conditions. The fluxes estimated from
the CO2 profiles were highly correlated to the direct measurements when the soil was neither very dry nor very wet. This suggests
that a better parameterization of the soil CO2 diffusivity is required for these soil moisture extremes. 相似文献
12.
Non-phototrophic CO
2
fixation by soil microorganisms 总被引:1,自引:0,他引:1
Anja Miltner Frank-Dieter Kopinke Reimo Kindler Draženka Selesi Anton Hartmann Matthias Kästner 《Plant and Soil》2005,269(1-2):193-203
Although soils are generally known to be a net source of CO2 due to microbial respiration, CO2 fixation may also be an important process. The non-phototrophic fixation of CO2 was investigated in a tracer experiment with 14CO2 in order to obtain information about the extent and the mechanisms of this process. Soils were incubated for up to 91 days
in the dark. In three independent incubation experiments, a significant transfer of radioactivity from 14CO2 to soil organic matter was observed. The process was related to microbial activity and could be enhanced by the addition
of readily available substrates such as acetate. CO2 fixation exhibited biphasic kinetics and was linearly related to respiration during the first phase of incubation (about
20–40 days). The fixation amounted to 3–5% of the net respiration. After this phase, the CO2 fixation decreased to 1–2% of the respiration. The amount of carbon fixed by an agricultural soil corresponded to 0.05% of
the organic carbon present in the soil at the beginning of the experiment, and virtually all of the fixed CO2 was converted to organic compounds. Many autotrophic and heterotrophic biochemical processes result in the fixation of CO2. However, the enhancement of the fixation by addition of readily available substrates and the linear correlation with respiration
suggested that the process is mainly driven by aerobic heterotrophic microorganisms. We conclude that heterotrophic CO2 fixation represents a significant factor of microbial activity in soils. 相似文献
13.
Impacts of increased atmospheric CO<Subscript>2</Subscript> concentration on photosynthesis and growth of micro- and macro-algae 总被引:1,自引:0,他引:1
Marine photosynthesis drives the oceanic biological CO2 pump to absorb CO2 from the atmosphere, which sinks more than one third of the industry-originated CO2 into the ocean. The increasing atmospheric CO2 and subsequent rise of pCO2 in seawater, which alters the carbonate system and related chemical reactions and results in lower pH and higher HCO3
− concentration, affect photosynthetic CO2 fixation processes of phytoplanktonic and macroalgal species in direct and/or indirect ways. Although many unicellular and
multicellular species can operate CO2-concentrating mechanisms (CCMs) to utilize the large HCO3
− pool in seawater, enriched CO2 up to several times the present atmospheric level has been shown to enhance photosynthesis and growth of both phytoplanktonic
and macro-species that have less capacity of CCMs. Even for species that operate active CCMs and those whose photosynthesis
is not limited by CO2 in seawater, increased CO2 levels can down-regulate their CCMs and therefore enhance their growth under light-limiting conditions (at higher CO2 levels, less light energy is required to drive CCM). Altered physiological performances under high-CO2 conditions may cause genetic alteration in view of adaptation over long time scale. Marine algae may adapt to a high CO2 oceanic environment so that the evolved communities in future are likely to be genetically different from the contemporary
communities. However, most of the previous studies have been carried out under indoor conditions without considering the acidifying
effects on seawater by increased CO2 and other interacting environmental factors, and little has been documented so far to explain how physiology of marine primary
producers performs in a high-CO2 and low-pH ocean. 相似文献
14.
This study examined the effects of season-long exposure of Chinese pine (Pinus tabulaeformis) to elevated carbon dioxide (CO2) and/or ozone (O3) on indole-3-acetic acid (IAA) content, activities of IAA oxidase (IAAO) and peroxidase (POD) in needles. Trees grown in
open-top chambers (OTC) were exposed to control (ambient O3, 55 nmol mol−1 + ambient CO2, 350 μmol mol−1, CK), elevated CO2 (ambient O3 + high CO2, 700 μmol mol−1, EC) and elevated O3 (high O3, 80 ± 8 nmol mol−1 + ambient CO2, EO) OTCs from 1 June to 30 September. Plants grown in elevated CO2 OTC had a growth increase of axial shoot and needle length, compared to control, by 20% and 10% respectively, while the growth
in elevated O3 OTC was 43% and 7% less respectively, than control. An increase in IAA content and POD activity and decrease in IAAO activity
were observed in trees exposed to elevated CO2 concentration compared with control. Elevated O3 decreased IAA content and had no significant effect on IAAO activity, but significantly increased POD activity. When trees
pre-exposed to elevated CO2 were transferred to elevated O3 (EC–EO) or trees pre-exposed to elevated O3 were transferred to elevated CO2 (EO–EC), IAA content was lower while IAAO activity was higher than that transferred to CK (EC–CK or EO–CK), the change in
IAA content was also related to IAAO activity. The results indicated that IAAO and POD activities in Chinese pine needles
may be affected by the changes in the atmospheric environment, resulting in the change of IAA metabolism which in turn may
cause changes in Chinese pine’s growth.
An erratum to this article can be found at 相似文献
15.
Somesh Mishra Suresh Gupta Smita Raghuvanshi Pratibha Pal 《Bioprocess and biosystems engineering》2016,39(8):1247-1258
The ongoing work on global warming resulting from green house gases (GHGs) has led to explore the possibility of bacterial strains which can fix carbon dioxide (CO2) and can generate value-added products. The present work is an effort in this direction and has carried out an exhaustive batch experiments for the fixation of CO2 using B. Cereus SM1 isolated from sewage treatment plant (STP). The work has incorporated 5-day batch run for gaseous phase inlet CO2 concentration of 13 ± 1 % (%v/v). 84.6 (±5.76) % of CO2 removal was obtained in the gaseous phase at mentioned CO2 concentration (%v/v). Energetic requirement for CO2 fixation was assessed by varying Fe[II] ion concentration (0–200 ppm) on the per-day basis. The cell lysate obtained from CO2 fixation studies (Fe[II] ion = 100 ppm) was analyzed using Fourier transformation infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC–MS). This analysis confirmed the presence of fatty acids and hydrocarbon as valuable products. The hydrocarbons were found in the range of C11–C22 which is equivalent to light oil. The obtained fatty acids were found in the range of C11–C19. The possibility of fatty acid conversion to biodiesel was explored by carrying out the transesterification reaction. The yield of biodiesel was obtained as 86.5 (±0.048) % under the transesterification reaction conditions. Results of this research work can provide the valuable information in the implementation of biomitigation of CO2 at real scenario. 相似文献
16.
We enriched in CO2 the canopy of 14 broad-leaved trees in a species-rich, ca. 30-m-tall forest in NW Switzerland to test whether elevated CO2 reduces water use in mature forest trees. Measurements of sap flux density (JS) were made prior to CO2 enrichment (summer 2000) and throughout the first whole growing season of CO2 exposure (2001) using the constant heat-flow technique. The short-term responses of sap flux to brief (1.5–3 h) interruptions of CO2 enrichment were also examined. There were no significant a priori differences in morphological and physiological traits between trees which were later exposed to elevated CO2 (n=14) and trees later used as controls (n=19). Over the entire growing season, CO2 enrichment resulted in an average 10.7% reduction in mean daily JS across all species compared to control trees. Responses were most pronounced in Carpinus, Acer, Prunus and Tilia, smaller in Quercus and close to zero in Fagus trees. The JS of treated trees significantly increased by 7% upon transient exposure to ambient CO2 concentrations at noon. Hence, responses of the different species were, in the short term, similar in magnitude to those observed over the whole season (though opposite because of the reversed treatment). The reductions in mean JS of CO2-enriched trees were high (22%) under conditions of low evaporative demand (vapour pressure deficit, VPD <5 hPa) and small (2%) when mean daily VPD was greater than 10 hPa. During a relatively dry period, the effect of elevated CO2 on JS even appeared to be reversed. These results suggest that daily water savings by CO2-enriched trees may have accumulated to a significantly improved water status by the time when control trees were short of soil moisture. Our data indicate that the magnitude of CO2 effects on stand transpiration will depend on rainfall regimes and the relative abundance of the different species, being more pronounced under humid conditions and in stands dominated by species such as Carpinus and negligible in mono-specific Fagus forests. 相似文献
17.
Plant communities around natural CO2 springs have been exposed to elevated CO2 levels over many generations and give us a unique opportunity to investigate the effects of long-term elevated CO2 levels on wild plants. We searched for natural CO2 springs in cool temperate climate regions in Japan and found three springs that were suitable for studying long-term responses
of plants to elevated levels of CO2: Ryuzin-numa, Yuno-kawa and Nyuu. At these CO2 springs, the surrounding air was at high CO2 concentration with no toxic gas emissions throughout the growth season, and there was natural vegetation around the springs.
At each site, high-CO2 (HC) and low-CO2 (LC) plots were established, and three dominant species at the shrub layers were used for physiological analyses. Although
the microenvironments were different among the springs, dicotyledonous species growing at the HC plots tended to have more
starch and less nitrogen per unit dry mass in the leaves than those growing at the LC plots. In contrast, monocotyledonous
species growing in the HC and LC plots had similar starch and nitrogen concentrations. Photosynthetic rates at the mean growth
CO2 concentration were higher in HC plants than LC plants, but photosynthetic rates at a common CO2 concentration were lower in HC plants. Efficiency of water and nitrogen use of leaves at growth CO2 concentration was greatly increased in HC plants. These results suggest that natural plants growing in elevated CO2 levels under cool temperate climate conditions have down-regulated their photosynthetic capacity but that they increased
photosynthetic rates and resource use efficiencies due to the direct effect of elevated CO2 concentration. 相似文献
18.
The importance and meaning of social and recreational travel for a diverse group of Auckland residents is explored in this
article. Study participants identified a range of social and health benefits, including maintaining social connections with
family and friends, opportunities to participate in physical activity, and reducing stress. However, many of these trips are
by car. New Zealand has one of the highest rates of private car ownership internationally, low-density urban development,
and a poor public transport infrastructure. Social and recreational trips make up a sizeable proportion of domestic travel
and are contributing to New Zealand’s increasing rate of CO2 emissions. There is an obvious need to address the negative ecological impacts of human activity. Our findings suggest that
alongside strategies to reduce CO2 emissions, it also is important to introduce measures to maintain the benefits from social and recreational travel. Suggestions
are made for further areas of research. 相似文献
19.
The increasing CO2 concentration in Earths atmosphere is expected to cause a greater decline in the nutritional quality of C3 than C4 plants. As a compensatory response, herbivorous insects may increase their feeding disproportionately on C3 plants. These hypotheses were tested by growing the grasses Lolium multiflorum C3) and Bouteloua curtipendula C4) at ambient (370 ppm) and elevated (740 ppm) CO2 levels in open top chambers in the field, and comparing the growth and digestive efficiencies of the generalist grasshopper Melanoplus sanguinipes on each of the four plant × CO2 treatment combinations. As expected, the nutritional quality of the C3 grass declined to a greater extent than did that of the C4 grass at elevated CO2; protein levels declined in the C3 grass, while levels of carbohydrates (sugar, fructan and starch) increased. However, M. sanguinipes did not significantly increase its consumption rate to compensate for the lower nutritional quality of the C3 grass grown under elevated CO2. Instead, these grasshoppers appear to use post-ingestive mechanisms to maintain their growth rates on the C3 grass under elevated CO2. Consumption rates of the C3 and C4 grasses were also similar, demonstrating a lack of compensatory feeding on the C4 grass. We also examined the relative efficiencies of nutrient utilization from a C3 and C4 grass by M. sanguinipes to test the basis for the C4 plant avoidance hypothesis. Contrary to this hypothesis, neither protein nor sugar was digested with a lower efficiency from the C4 grass than from the C3 grass. A novel finding of this study is that fructan, a potentially large carbohydrate source in C3 grasses, is utilized by grasshoppers. Based on the higher nutrient levels in the C3 grass and the better growth performance of M. sanguinipes on this grass at both CO2 levels, we conclude that C3 grasses are likely to remain better host plants than C4 grasses in future CO2 conditions. 相似文献
20.
To develop an integrated process of CO2-fixation and H2 photoproduction by marine green microalga Platymonas subcordiformis, the impact of algal cells grown in CO2-supplemented air bubble column bioreactor was investigated on H2 photoproduction regulated by carbonylcyanide m-chlorophenylhrazone. Highest cell growth (3.85 × 106 cells ml−1), starch content (0.25 ± 0.08 mg per 106 cells) and hydrogen production (50 ± 3 ml l−1) were achieved at 3% CO2-supplemented culture, which are respectively 1.4, 2.1, 1.5-fold of the air-supplemented culture. Improved H2 production correlated well with the increase in starch accumulation. In this process, the algal cells have been recycled
for stable H2 production of 40–50 ml l−1 over five cycles. 相似文献