共查询到20条相似文献,搜索用时 31 毫秒
1.
Aquatic and aerial respiration of the amphibious fishes Lipophrys pholis and Periophthalmus barbarus were examined using a newly designed flow-through respirometer system. The system allowed long-term measurements of oxygen consumption and carbon dioxide release during periods of aquatic and aerial respiration. The M o 2 of L. pholis , measured at 15° C, was 2·1 μmol O2 g–1 h–1 during aquatic and 1·99 μmol O2 g–1 h–1 during aerial exposure. The corresponding values of the M co2 were 1.67 and 1.59 μmol O2 g–1 h–1 respectively, giving an aquatic respiratory exchange ratio (RER) of 0·80 and an aerial RER of 0·79. The M o2 of P. barbarus , measured at 28°C, was 4·05 μmol O2 g–1 h–1 during aquatic and 3·44 μmol O2 g–1 h–1 during aerial exposure. The corresponding values of the Mco2 were 3·29 μmol CO2 g–1 h–1 and 2·63 μmol CO2 g–1 h–1 respectively, giving an aquatic RER of 0·81 and an aerial RER of 0·77. While exposed to air for at least 10 h, both species showed no decrease in metabolic rate or carbon dioxide release. The RER of these fishes equalled their respiratory quotient. After re-immersion an increased oxygen consumption, due to the payment of an oxygen debt, could not be detected. 相似文献
2.
Seedlings of two tree species from the Atlantic lowlands of Costa Rica, Ochroma la-gopus Swartz, a fast-growing pioneer species, and Pentaclethra macroloba (Willd.) Kuntze, a slower-growing climax species, were grown under enriched atmospheric CO2 in controlled environment chambers. Carbon dioxide concentrations were maintained at 350 and 675 μl 1−1 under photosynthetic photon flux densities of 500 μol m−2 s−1 and temperatures of 26°C day and 20°C night. Total biomass of both species increased significantly in the elevated CO2 treatment; the increase in biomass was greatest for the pioneer species, O. lagopus . Both species had greater leaf areas and specific leaf weights with increased atmospheric CO2 . However, the ratio of non-pho-tosynthetic tissue to leaf area also increased in both species leading to decreased leaf area ratios. Plants of both species grown at 675 μl 1−1 CO2 had lower chlorophyll contents and photosynthesis on a leaf area basis than those grown at 350 μl 1−1 . Reductions in net photosynthesis occurred despite increased internal CO2 concentrations in the CO2 -enriched treatment. Stomatal conductances of both species decreased with CO2 -enrichment resulting in significant increases in water use efficiency. 相似文献
3.
Two Italian CO2 springs allowed us to study the long-term effect of a 350–2600 μ mol mol–1 increase in CO2 concentrations on the surface structures of leaves of Quercus ilex L. Carbon dioxide increased the quantity of cuticular waxes, above an apparent threshold of 750 μ mol mol–1 CO2 . Leaf wettability was not modified by CO2 concentrations. Reduction in stomatal frequency was observable up to 750 μ mol mol–1 CO2 , the slope being almost the same as that estimated for the increase in CO2 concentration from pre-industrial times to the present. At higher concentrations, CO2 seemed to exert no more impact on stomatal frequency. 相似文献
4.
Yield of wheat across a subambient carbon dioxide gradient 总被引:1,自引:0,他引:1
Yields and yield components of two cultivars of day-neutral spring wheat ( Triticum aestivum L.) were assessed along a gradient of daytime carbon dioxide (CO2 ) concentrations from about 200 to near 350 μmol CO2 (mol air)–1 in a 38 m-long controlled environment chamber. The range in CO2 concentration studied approximates that of Earth's atmosphere since the last ice age. This 75% rise in CO2 concentration increased grain yields more than 200% under well-watered conditions and by 80–150% when wheat was grown without additions of water during the last half of the 100-day growing season. The 27% increase in CO2 from the pre-industrial level of 150 years ago (275 μmol mol–1 ) to near the current concentration (350 μmol mol–1 ) increased grain yields of 'Yaqui 54' and 'Seri M82' spring wheats by 55% and 53%, respectively, under well-watered conditions. Yield increased because of greater numbers of grains per spike, rather than heavier grains or numbers of spikes per plant. Water use increased little with CO2 concentration, resulting in improved water use efficiency as CO2 rose. Data suggest that rising CO2 concentration contributed to the substantial increase in average wheat yields in the U.S. during recent decades. 相似文献
5.
Ananas comosus L. (Merr.) (pineapple) was grown at three day/night temperatures and 350 (ambient) and 700 (elevated) μ mol mol–1 CO2 to examine the interactive effects of these factors on leaf gas exchange and stable carbon isotope discrimination ( Δ ,‰). All data were collected on the youngest mature leaf for 24 h every 6 weeks. CO2 uptake (mmol m–2 d–1 ) at ambient and elevated CO2 , respectively, were 306 and 352 at 30/20 °C, 175 and 346 at 30/25 °C and 187 and 343 at 35/25 °C. CO2 enrichment enhanced CO2 uptake substantially in the day in all environments. Uptake at night at elevated CO2 , relative to that at ambient CO2 , was unchanged at 30/20 °C, but was 80% higher at 30/25 °C and 44% higher at 35/25 °C suggesting that phosphoenolpyruvate carboxylase was not CO2 -saturated at ambient CO2 levels and a 25 °C night temperature. Photosynthetic water use efficiency (WUE) was higher at elevated than at ambient CO2 . Leaf Δ -values were higher at elevated than at ambient CO2 due to relatively higher assimilation in the light. Leaf Δ was significantly and linearly related to the fraction of total CO2 assimilated at night. The data suggest that a simultaneous increase in CO2 level and temperature associated with global warming would enhance carbon assimilation, increase WUE, and reduce the temperature dependence of CO2 uptake by A. comosus . 相似文献
6.
The role of temperature in determining the stimulation of CO2 assimilation at elevated carbon dioxide concentration in soybean seedlings 总被引:1,自引:0,他引:1
Soybean ( Glycine max cv. Clark) was grown at both ambient (ca 350 μmol mol−1 ) and elevated (ca 700 μmol mol−1 ) CO2 concentration at 5 growth temperatures (constant day/night temperatures of 20, 25, 30, 35 and 40°C) for 17–22 days after sowing to determine the interaction between temperature and CO2 concentration on photosynthesis (measured as A, the rate of CO2 assimilation per unit leaf area) at both the single leaf and whole plant level. Single leaves of soybean demonstrated increasingly greater stimulation of A at elevated CO2 as temperature increased from 25 to 35°C (i.e. optimal growth rates). At 40°C, primary leaves failed to develop and plants eventually died. In contrast, for both whole plant A and total biomass production, increasing temperature resulted in less stimulation by elevated CO2 concentration. For whole plants, increased CO2 stimulated leaf area more as growth temperature increased. Differences between the response of A to elevated CO2 for single leaves and whole plants may be related to increased self-shading experienced by whole plants at elevated CO2 as temperature increased. Results from the present study suggest that self-shading could limit the response of CO2 assimilation rate and the growth response of soybean plants if temperature and CO2 increase concurrently, and illustrate that light may be an important consideration in predicting the relative stimulation of photosynthesis by elevated CO2 at the whole plant level. 相似文献
7.
A controlled-environment chamber for measurement of canopy photosynthesis by small stands of lettuce (Lactuca sativa L.) 总被引:2,自引:0,他引:2
Abstract. A controlled-environment chamber constructed from a standard chest freezer was used to grow and measure the CO2 exchange of small stands of lettuce ( Lactuca sativa L. ev. Ambassador). The chamber, with horizontal air flow, provided good control of air temperature ( c. 6 to 16°C), irradiance (0–300 μmol PAR m 2 S1 and CO2 (350–1000 μmol mol−1 ). The photosynthetic response to changes in these variables was measured using an inexpensive CO2 dosing system which recorded the input rate required to maintain a constant concentration of CO2 (to ± 2.5%). Characteristis of the growth environment and the changes in response to temperature and irradiance are described. 相似文献
8.
Photosynthetic response of Eragrostis tef to temperature 总被引:1,自引:0,他引:1
Photosynthetic characteristics of leaves of tef, Eragrostis tef (Zucc.) Trotter, plants, grown at 25/15°C (day/night), were measured at temperatures from 18 to 48°C. The highest carbon exchange rates (CER) occurred between 36 and 42°C. and averaged 27 μmol m−2 s−1 . At lower or higher temperatures, CER was reduced, but the availability of CO2 to the mesophyll, measured as internal CO2 concentration, was highest when temperatures were above or below the optimum for CER. In addition, CER and stomatal conductance were not correlated, but residual conductance was highly correlated with CER (r = 0.98). In additional experiments, relative 13 C composition for leaf tissue grown at 25, 35 and 45°C averaged -14.4 per mille, confirming that tef is a C4 grass species. Dry matter accumulation was higher at 35 than at 25, and lowest at 45°C. Leaf CER rates increased hyperbolically with increased light when measured from 0 to 2000 μmol m−2 s−1 PPFD. The highest CER, 31.8 μ-mol m-2 s−1 , occurred at 35°C and 2000 μmol m−2 s−1 PPFR. At high light, CER at 25 and 35°C were nearly equal because of higher stomatal conductance at 25°C. Residual conductance was, however, clearly highest at 35°C compared to 25 and 45°C treatments. Stomatal conductance and residual conductance were not correlated in either set of experiments, yet residual conductance was always highest when temperatures were between 35 and 42°C across experiments, suggesting that internal leaf photosynthetic potential was highest across that temperature range. 相似文献
9.
Interaction of enriched CO2 and water stress on the physiology of and biomass production in sweet potato grown in open-top chambers 总被引:2,自引:2,他引:0
N. C. BHATTACHARYA D. R. HILEMAN P. P. GHOSH R. L. MUSSER S. BHATTACHARYA P. K. BISWAS 《Plant, cell & environment》1990,13(9):933-940
Abstract. The objective of this study was to investigate the effects of water stress in sweet potato ( Ipomoea batatas L. [Lam] 'Georgia Jet') on biomass production and plant-water relationships in an enriched CO2 atmosphere. Plants were grown in pots containing sandy loam soil (Typic Paleudult) at two concentrations of elevated CO2 and two water regimes in open-top field chambers. During the first 12 d of water stress, leaf xylem potentials were higher in plants grown in a CO2 concentration of 438 and 666 μmol mol−1 than in plants grown at 364 μmol mol−1 . The 364 μmol mol−1 CO2 grown plants had to be rewatered 2 d earlier than the high CO2 -grown plants in response to water stress. For plants grown under water stress, the yield of storage roots and root: shoot ratio were greater at high CO2 than at 364 μmol mol−1 ; the increase, however, was not linear with increasing CO2 concentrations. In well-watered plants, biomass production and storage root yield increased at elevated CO2 , and these were greater as compared to water-stressed plants grown at the same CO2 concentration. 相似文献
10.
The interaction of high temperature and elevated CO2 on photosynthetic acclimation of single leaves of rice in situ 总被引:1,自引:0,他引:1
Rice ( Oryza sativa L. cv. IR72) was grown at three different CO2 concentrations (ambient, ambient + 200 μmol mol−1 , ambient + 300 μmol mol−1 ) at two different growth temperatures (ambient, ambient + 4°C) from sowing to maturity to determine longterm photosynthetic acclimation to elevated CO2 with and without increasing temperature. Single leaves of rice showed a cooperative enhancement of photosynthetic rate with elevated CO2 and temperature during tillering, relative to the elevated CO2 condition alone. However, after flowering, the degree of photosynthetic stimulation by elevated CO2 was reduced for the ambient + 4°C treatment. This increasing insensitivity to CO2 appeared to be accompanied by a reduction in ribulose-1.5-bisphosphate carboxylase/oxygenase (Rubisco) activity and/or concentration as evidenced by the reduction in the assimilation (A) to internal CO2 (C1 ) response curve. The reproductive response (e.g. percent filled grains, panicle weight) was reduced at the higher growth temperature and presumably reflects a greater increase in floral sterility. Results indicate that while CO2 and temperature could act synergistically at the biochemical level, the direct effect of temperature on floral development with a subsequent reduction in carbon utilization may change sink strength so as to limit photosynthetic stimulation by elevated CO2 concentration. 相似文献
11.
Effect of Hyperbaric Carbon Dioxide Pressure on the Microbial Flora of Pork Stored at 4 or 14°C 总被引:1,自引:1,他引:0
Changes in the microbial flora of pork stored at 4 or 14°C were studied in 5 atm CO2 , 1 atm CO2 or 1 atm air. The time needed for the total aerobic count at 4°C to reach 5 × 106 organisms/cm2 was about three times longer in 5 atm CO2 than in 1 atm CO2 , and about 15 times longer in 5 atm CO2 than in air. At 14°C there was no difference in growth rate between 5 atm CO2 and 1 atm CO2 . No off-odour was detected after storage in 5 atm CO2 for 14 d, but the pork in 1 atm CO2 (6 d) was organoleptically unacceptable.
The predominant organisms on the pork from the processing line were: Flavobacterium spp., Acinetobacter calcoaceticus, Pseudomonas spp., Micrococcus spp. and Moraxella spp. After aerobic storage at 4°C (8 d) or 14°C (3 d) more than 90% of the flora consisted of Pseudomonas spp. At 4°C all Pseudomonas spp. were of the non-fluorescent type, whilst at 14°C 32% were Ps. putida and Ps. fluorescens. After storage in 1 atm CO2 Lactobacillus spp. represented 66% of the flora at 14°C (6 d) and 100% at 4°C (40 d), with L. xylosus dominating. After storage in 5 atm CO2 Lactobacillus spp. constituted the total flora at both temperatures with L. lactis (14°C) and L. xylosus (4°C) dominating.
It was concluded that high partial pressures of CO2 have a considerable shelf-life prolonging effect by (i) selecting the microflora towards Lactobacillus spp. and (ii) reducing the growth rate of these Lactobacillus spp. The controlling and growth inhibitory effect of CO2 was promoted by reduced temperatures. 相似文献
The predominant organisms on the pork from the processing line were: Flavobacterium spp., Acinetobacter calcoaceticus, Pseudomonas spp., Micrococcus spp. and Moraxella spp. After aerobic storage at 4°C (8 d) or 14°C (3 d) more than 90% of the flora consisted of Pseudomonas spp. At 4°C all Pseudomonas spp. were of the non-fluorescent type, whilst at 14°C 32% were Ps. putida and Ps. fluorescens. After storage in 1 atm CO
It was concluded that high partial pressures of CO
12.
Photoinhibition of photosynthesis in Lemna gibba as induced by the interaction between light and temperature. I. Photosynthesis in vivo 总被引:2,自引:0,他引:2
The floating angiosperm Lemna gibba L. was exposed for 2 h to various combinations of photosynthetic photon flux densities and temperature. The extent of photoinhibition of photosynthesis was assayed by measuring the net CO2 uptake before and after a photoinhibitory treatment, and the time course for photoinhibition was studied. It was found that the maximum quantum yield and the light-saturated rate of CO2 uptake were affected by the interaction between light and temperature during the photoinhibitory treatment. At a constant photon flux density of 650 μmol m−2 s−1 the extent of photoinhibition increased with decreasing temperature showing that even a chilling-resistant plant like L. gibba is much more susceptible to photoinhibition at chilling temperatures. About 60% photoinhibition of the quantum yield for CO2 uptake could be obtained either by a high photon flux density of 1 750 μmol m−2 s−1 and 25°C or by a moderate photon flux density of 650 μmol m−2 s−1 and 3°C. The time courses of recovery from 60% photoinhibition produced by either of these two treatments were similar, indicating that the nature of the photoinhibition was intrinsically similar. The extent of photoinhibition was related to the amount of light absorbed in excess to what could be handled by photosynthesis at that temperature. The vital importance of photosynthesis in alleviating photoinhibition is discussed. 相似文献
13.
Changes in the temperature dependence of the photosynthetic rate depending on growth temperature were investigated for a temperate evergreen tree, Quercus myrsinaefolia . Plants were grown at 250 μ mol quanta m–2 s–1 under two temperature conditions, 15 and 30 °C. The optimal temperature that maximizes the light-saturated rate of photosynthesis at 350 μ L L–1 CO2 was found to be 20–25 and 30–35 °C for leaves grown at 15 and 30 °C, respectively. We focused on two processes, carboxylation and regeneration of ribulose-1,5-bisphosphate (RuBP), which potentially limit photosynthetic rates. Because the former process is known to limit photosynthesis at lower CO2 concentrations while the latter limits it at higher CO2 concentrations, we determined the temperature dependence of the photosynthetic rate at 200 and 1000 μ L L–1 CO2 under saturated light. It was revealed that the temperature dependence of both processes varied depending on the growth temperature. Using a biochemical model, we estimated the capacity of the two processes at various temperatures under ambient CO2 concentration. It was suggested that, in leaves grown at low temperature (15 °C), the photosynthetic rate was limited solely by RuBP carboxylation under any temperature. On the other hand, it was suggested that, in leaves grown at high temperature (30 °C), the photosynthetic rate was limited by RuBP regeneration below 22 °C, but limited by RuBP carboxylation above 22 °C. We concluded that: (1) the changes in the temperature dependence of carboxylation and regeneration of RuBP and (2) the changes in the balance of these two processes altered the temperature dependence of the photosynthetic rate. 相似文献
14.
Effect of High Concentrations of Carbon Dioxide on Growth Rate of Pseudomonas fragi, Bacillus cereus and Streptococcus cremoris 总被引:5,自引:1,他引:4
The maximum specific growth rates of Pseudomonas fragi, Bacillus cereus and Streptococcus cremoris were studied over a wide range of carbon dioxide concentrations. The growth rate compared with a control was reduced to 50% in Ps. fragi at 0–5 atm CO2 , in B. cereus at 1—3 atm and in Strep, cremoris at 8–6 atm. B. cereus and Strep, cremoris were completely inhibited at 3 and 11 atm CO2 , respectively. The growth rate of the aerobic Ps. fragi at 0–99 atm CO2 (0–01 atm oxygen) was reduced to about 20% of that in air. The growth rate of Ps. fragi was decreased at oxygen concentrations lower than 0–01 atm.
When Ps. fragi was grown at oxygen limitation (0.0025 atm oxygen) and exposed to 0.99 atm CO2 , the inhibiting effect of the CO2 was added to that of the oxygen limitation. No indications of a synergistic effect between CO2 inhibition and oxygen limitation were noted.
B. cereus and Strep, cremoris were tested under anaerobic conditions. 相似文献
When Ps. fragi was grown at oxygen limitation (0.0025 atm oxygen) and exposed to 0.99 atm CO
B. cereus and Strep, cremoris were tested under anaerobic conditions. 相似文献
15.
Coventry Hickey Mawson Drew Wan Krause & Boghossian 《Letters in applied microbiology》1998,26(6):427-431
The effects of 80% oxygen–20% carbon dioxide (O2 –CO2 ) and 80% nitrogen–20% carbon dioxide (N2 –CO2 ) atmospheres were compared with respect to the microbial and sensory characteristics of vacuum skin-packaged grain-fed beef steaks stored at −1 and 4 °C. In both N2 –CO2 and O2 –CO2 atmospheres, lactobacilli were predominant over Brochothrix , pseudomonads, enterobacteria and yeasts and moulds. The results of the current investigation showed that the O2 –CO2 atmospheres did not yield total viable counts in excess of 105 cfu cm−2 on beef steaks after 4 weeks of storage. However, the sensory analysis and thiobarbituric acid (TBA) values (as a measure of oxidative rancidity) of the products were unacceptable at this time. In contrast, the N2 –CO2 atmospheres yielded maximum total viable counts of approximately 107 cfu cm−2 and the sensory analysis and TBA values of the product were judged to be acceptable after 4 weeks of storage at −1 °C. These results indicate that sensory effects of the product were influenced to a greater extent by the chemical effects of high concentration of O2 on rancidity than by the high levels of lactobacilli. 相似文献
16.
Plant responses to elevated CO2 can be modified by many environmental factors, but very little attention has been paid to the interaction between CO2 and changes in vapour pressure deficit (VPD). Thirty-day-old alfalfa plants ( Medicago sativa L. cv. Aragón), which were inoculated with Sinorhizobium meliloti 102F78 strain, were grown for 1 month in controlled environment chambers at 25/15°C, 14 h photoperiod, and 600 µmol m−2 s−1 photosynthetic photon flux (PPF), using a factorial combination of CO2 concentration (400 µmol mol−1 or 700 µmol mol−1 ) and vapour pressure deficit (0.48 kPa or 1.74 kPa, which corresponded to relative humidities of 85% and 45% at 25°C, respectively). Elevated CO2 strongly stimulated plant growth under high VPD conditions, but this beneficial effect was not observed under low VPD. Under low VPD, elevated CO2 also did not enhance plant photosynthesis, and plant water stress was greatest for plants grown at elevated CO2 and low VPD. Moreover, plants grown under elevated CO2 and low VPD had a lower leaf soluble protein and photosynthetic activity (photosynthetic rate and carboxylation efficiency) than plants grown under elevated CO2 and high VPD. Elevated CO2 significantly increased leaf adaxial and abaxial temperatures. Because the effects of elevated CO2 were dependent on vapour pressure deficit, VPD needs to be controlled in experiments studying the effect of elevated CO2 as well as considered in the extrapolations of results to a warmer, high-CO2 world. 相似文献
17.
Effect of elevated CO2 on the stomatal distribution and leaf physiology of Alnus glutinosa 总被引:1,自引:1,他引:0
Variation in stomatal development and physiology of mature leaves from Alnus glutinosa plants grown under reference (current ambient, 360 μmol mol−1 CO2 ) and double ambient (720 μmol mol−1 CO2 ) carbon dioxide (CO2 ) mole fractions is assessed in terms of relative plant growth, stomatal characters (i.e. stomatal index and density) and leaf photosynthetic characters. This is the first study to consider the effects of elevated CO2 concentration on the distribution of stomata and epidermal cells across the whole leaf and to try to ascertain the cause of intraleaf variation. In general, a doubling of the atmospheric CO2 concentration enhanced plant growth and significantly increased stomatal index. However, there was no significant change in relative stomatal density. Under elevated CO2 concentration there was a significant decrease in stomatal conductance and an increase in assimilation rate. However, no significant differences were found for the maximum rate of carboxylation ( V cmax ) and the light saturated rate of electron transport ( J max ) between the control and elevated CO2 treatment. 相似文献
18.
KATRI KOSTIAINEN SEIJA KAAKINEN PEKKA SARANPÄĆ BJARNI D. SIGURDSSON‡ SVEN-OLOF LUNDQVIST§ SUNE LINDER¶ ELINA VAPAAVUORI 《Global Change Biology》2009,15(2):368-379
The objective of the study was to investigate the interactive effects of elevated atmospheric carbon dioxide concentration, [CO2 ], and temperature on the wood properties of mature field-grown Norway spruce ( Picea abies (L.) Karst.) trees. Material for the study was obtained from an experiment in Flakaliden, northern Sweden, where trees were grown for 3 years in whole-tree chambers at ambient (365 μmol mol−1 ) or elevated [CO2 ] (700 μmol mol−1 ) and ambient or elevated air temperature (ambient +5.6 °C in winter and ambient +2.8 °C in summer). Elevated temperature affected both wood chemical composition and structure, but had no effect on stem radial growth. Elevated temperature decreased the concentrations of acetone-soluble extractives and soluble sugars, while mean and earlywood (EW) cell wall thickness and wood density were increased. Elevated [CO2 ] had no effect on stem wood chemistry or radial growth. In wood structure, elevated [CO2 ] decreased EW cell wall thickness and increased tracheid radial diameter in latewood (LW). Some significant interactions between elevated [CO2 ] and temperature were found in the anatomical and physical properties of stem wood (e.g. microfibril angle, and LW cell wall thickness and density). Our results show that the wood material properties of mature Norway spruce were altered under exposure to elevated [CO2 ] and temperature, although stem radial growth was not affected by the treatments. 相似文献
19.
The effects of elevated atmospheric CO2 on lipid metabolism in leaves from mature wheat (Triticum aestivum cv. Hereward) plants 总被引:1,自引:0,他引:1
M. Williams E. J. Robertson R. M. Leech & J. L. Harwood 《Plant, cell & environment》1998,21(8):927-936
Winter wheat (Triticum aestivum L. cv. Hereward) plants were grown for 35 d either at 350 μ mol mol–1 CO2 or at 650 μ mol mol–1 CO2 . Lipid synthesis was studied in these plants by incubating the 5th leaf on the main stem with [1–14 C]acetate. Increased CO2 concentrations did not significantly affect the total incorporation of radiolabel into lipids of whole leaf tissue, but altered the distribution for individual lipid classes. Most noticeable amongst acyl lipids was the reduction in labelling of diacylglycerol and a corresponding increase in the proportion of phosphatidylcholine labelling. In the basal regions, there were similar changes and, in addition, phosphatidylglycerol labelling was particularly increased following growth in an enriched CO2 atmosphere. The stimulation of labelling of the mitochondrial-specific lipid, diphosphatidylglycerol, prompted an examination of the mitochondrial population in wheat plants. Mitochondria were localized in intact wheat sections by immunolabelling for the mitochondrial-specific chaperonin probe. Growth in elevated CO2 doubled the number of mitochondria compared to growth in ambient CO2 . Fatty acid labelling was also significantly influenced following growth at elevated CO2 concentrations. Most noticeable were the changes in 16C:18C ratios for the membrane lipids, phosphatidylcholine, phosphatidylglycerol and monogalactosyldiacylglycerol. These data imply a change in the apportioning of newly synthesized fatty acids between the 'eukaryotic' and 'prokaryotic' pathways of metabolism under elevated CO2 . 相似文献
20.
The effects of photon flux density and temperature on net photosynthesis and transpiration rates of mature and immature leaves of three-year-old Japanese larch Larix kaempferi (Lamb.) Sarg. trees were determined with an infrared, differential open gas analysis system. Net photosynthetic response to increasing photon flux densities was similar for different foliage positions and stage of maturity. Light compensation was between 25 and 50 μmol m−2 s−1 . Rates of photosynthesis increased rapidly at photon flux densities above the compensation level and became saturated between 800 and 1000 μmol m−2 s−1 . Transpiration rates at constant temperature likewise increased with increasing photon flux density, and leveled off between 800 and 1000 μmol m−2 s−1 . Photosynthetic response to temperature was determined in saturating light and was similar for all foliage positions; it increased steadily from low temperatures to an optimum range betweeen 15 and 21°C and then decreased rapidly above 21°C. Transpiration rate, however, increased continuously with rising temperature up to the experimental maximum. CO2 compensation concentrations for mature foliage varied between 58 and 59 μl l−1 ; however, foliage borne at the apex of the terminal leader compensated at 75 μl l−1 . None of these data support the claim that Japanese larch possesses C4 photosynthetic characteristics. 相似文献