Home  About us  Contact
 

Dark Respiration (dark + respiration)

Distribution by Scientific Domains
Life Sciences93%

Terms modified by Dark Respiration

  • dark respiration rate
    		•

    Selected Abstracts

    Respiratory carbon loss of calcareous grasslands in winter shows no effects of 4 years' CO2 enrichment

    FUNCTIONAL ECOLOGY, Issue 2 2002
    M. Volk
    Summary 1CO2 exchange measurements in long-term CO2 -enrichment experiments suggest large net carbon gains by ecosystems during the growing season that are not accounted for by above-ground plant biomass. Considerable amounts of C might therefore be allocated below ground. 2Winter ecosystem respiration from temperate grasslands under elevated CO2 may account for the loss of a significant part of the extra C gained during the growing season. To test this hypothesis, dark respiration was assessed throughout the winter of the fourth year of CO2 enrichment in a calcareous grassland. 3Using these data, a model was parameterized to estimate whole-winter respiratory CO2 losses. From November to February, 154 9 g C m,2 were respired under elevated CO2 and 144 5 g C m,2 under ambient [CO2], with no significant difference between the CO2 treatments. 4We conclude that (i) wintertime respiration does not constitute a larger C loss from the ecosystem at elevated CO2; and (ii) the absence of respiratory responses implies no extra growing-season C inputs with month-to-year turnover times at elevated CO2. [source]

    Leaf dark respiration as a function of canopy position in Nothofagus fusca trees grown at ambient and elevated CO2 partial pressures for 5 years

    FUNCTIONAL ECOLOGY, Issue 4 2001
    K. L. Griffin
    Summary 1,Mass-based and area-based rates of respiration, leaf nitrogen content, leaf total protein content, non-structural carbohydrates and leaf mass per unit area (LMA) all decreased with depth in the canopy of Nothofagus fusca (Hook. F.) Oerst. (Red beech) trees grown for 5 years at ambient (36 Pa) or elevated (66 Pa) CO2 partial pressures. 2Elevated CO2 partial pressure had a strong effect on dark respiration, decreasing both mass-based and area-based rates at all canopy positions, but had little or no effect on leaf physical and biochemical properties. 3Leaf sugars, starch, protein, N and LMA were all correlated with respiration rate, and are therefore strong predictors of area-based dark respiration rates. The y axis intercept of regressions of respiration rate on mean leaf N, protein, starch and LMA was lower for plants grown at elevated compared to ambient CO2 partial pressures because of the differential effect of growth at elevated CO2 partial pressure on leaf gas-exchange, chemical and physical characteristics. 4,The lower respiration rates for leaves from trees grown at elevated CO2 partial pressure resulted in a significant increase in the ratio of light-saturated net photosynthesis to respiration, increasing the potential carbon-use efficiency of these leaves. [source]

    Carbon dioxide balance of a fen ecosystem in northern Finland under elevated UV-B radiation

    GLOBAL CHANGE BIOLOGY, Issue 4 2009
    JAANA K. HAAPALA
    Abstract The effect of elevated UV-B radiation on CO2 exchange of a natural flark fen was studied in open-field conditions during 2003,2005. The experimental site was located in Sodankylä in northern Finland (67°22,N, 26°38,E, 179 m a.s.l.). Altogether 30 study plots, each 120 cm × 120 cm in size, were randomly distributed between three treatments (n=10): ambient control, UV-A control and UV-B treatment. The UV-B-treated plots were exposed to elevated UV-B radiation level for three growing seasons. The instantaneous net ecosystem CO2 exchange (NEE) and dark respiration (RTOT) were measured during the growing season using a closed chamber method. The wintertime CO2 emissions were estimated using a gradient technique by analyzing the CO2 concentration in the snow pack. In addition to the instantaneous CO2 exchange, the seasonal CO2 balances during the growing seasons were modeled using environmental data measured at the site. In general, the instantaneous NEE at light saturation was slightly higher in the UV-B treatment compared with the ambient control, but the gross photosynthesis was unaffected by the exposure. The RTOT was significantly lower under elevated UV-B in the third study year. The modeled seasonal (June,September) CO2 balance varied between the years depending on the ground water level and temperature conditions. During the driest year, the seasonal CO2 balance was negative (net release of CO2) in the ambient control and the UV-B treatment was CO2 neutral. During the third year, the seasonal CO2 uptake was 43±36 g CO2 -C m,2 in the ambient control and 79±45 g CO2 -C m,2 in the UV-B treatment. The results suggest that the long-term exposure to high UV-B radiation levels may slightly increase the CO2 accumulation to fens resulting from a decrease in microbial activity in peat. However, it is unlikely that the predicted development of the level of UV-B radiation would significantly affect the CO2 balance of fen ecosystems in future. [source]

    Promotion of 5-aminolevulinic acid on photosynthesis of melon (Cucumis melo) seedlings under low light and chilling stress conditions

    PHYSIOLOGIA PLANTARUM, Issue 2 2004
    Liang Ju Wang
    When melon seedlings (Cucumis melo L. Ximiya No. 1) were cultured in a growth chamber with about 150 µmol m,2 s,1 photon flux density, the leaf photosynthetic ability reduced dramatically as leaf position decreased from the top. The application of 5-aminolevulinic acid (ALA) solutions significantly increased the net photosynthetic rate (Pn) as well as apparent quantum yield (AQY), carboxylation efficiency (CE) and stomata conductance (Gs). After irrigation with 10 ml of ALA solution (10 mg l,1 or 100 mg l,1) per container filled with approximately 250 g clean sand for 3 days, the leaf Pn was about 40,200% higher than that of controls, and AQY, CE and Gs increased 21,271%, 55,210% and 60,335%, respectively. Furthermore, ALA treatments increased leaf chlorophyll content and soluble sugar levels, as well as the rate of dark respiration, but decreased the rate of respiration under light. On the other hand, after melon seedlings that had been cultured in the chamber suffered chilling at 8°C for 4 h and then recovered at 25,30°C for 2 and 20 h, the Pn of the water-irrigated plants was only 12,18% and 37,47%, respectively, compared with the initial Pn before chilling treatment. If the seedlings underwent the same treatment but with ALA (10 mg l,1), the respective Pn was 22,38% and 76,101%, compared with that of the control before chilling stress. If chilling was prolonged for 6 h, the ALA-pre-treated plants only showed a few symptoms in the leaf margins whereas all water-irrigated plants died, which suggested that ALA presumably promoted chilling tolerance of the plants under low light. [source]

    Local and systemic effects of two herbivores with different feeding mechanisms on primary metabolism of cotton leaves

    PLANT CELL & ENVIRONMENT, Issue 7 2009
    LILIAN SCHMIDT
    ABSTRACT Caterpillars and spider mites are herbivores with different feeding mechanisms. Spider mites feed on the cell content via stylets, while caterpillars, as chewing herbivores, remove larger amounts of photosynthetically active tissue. We investigated local and systemic effects of short-term caterpillar and spider mite herbivory on cotton in terms of primary metabolism and growth processes. After short-term caterpillar feeding, leaf growth and water content were decreased in damaged leaves. The glutamate/glutamine ratio increased and other free amino acids were also affected. In contrast, mild spider mite infestation did not affect leaf growth or amino acid composition, but led to an increase in total nitrogen and sucrose concentrations. Both herbivores induced locally increased dark respiration, suggesting an increased mobilization of storage compounds potentially available for synthesis of defensive substances, but did not affect assimilation and transpiration. Systemically induced leaves were not significantly affected by the treatments performed in this study. The results show that cotton plants do not compensate the loss of photosynthetic tissue with higher photosynthetic efficiency of the remaining tissue. However, early plant responses to different herbivores leave their signature in primary metabolism, affecting leaf growth. Changes in amino acid concentrations, total nitrogen and sucrose content may affect subsequent herbivore performance. [source]

    Comparison of the A,Cc curve fitting methods in determining maximum ribulose 1·5-bisphosphate carboxylase/oxygenase carboxylation rate, potential light saturated electron transport rate and leaf dark respiration

    PLANT CELL & ENVIRONMENT, Issue 2 2009
    ZEWEI MIAO
    ABSTRACT A review of the literature revealed that a variety of methods are currently used for fitting net assimilation of CO2,chloroplastic CO2 concentration (A,Cc) curves, resulting in considerable differences in estimating the A,Cc parameters [including maximum ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), potential light saturated electron transport rate (Jmax), leaf dark respiration in the light (Rd), mesophyll conductance (gm) and triose-phosphate utilization (TPU)]. In this paper, we examined the impacts of fitting methods on the estimations of Vcmax, Jmax, TPU, Rd and gm using grid search and non-linear fitting techniques. Our results suggested that the fitting methods significantly affected the predictions of Rubisco-limited (Ac), ribulose 1,5-bisphosphate-limited (Aj) and TPU -limited (Ap) curves and leaf photosynthesis velocities because of the inconsistent estimate of Vcmax, Jmax, TPU, Rd and gm, but they barely influenced the Jmax : Vcmax, Vcmax : Rd and Jmax : TPU ratio. In terms of fitting accuracy, simplicity of fitting procedures and sample size requirement, we recommend to combine grid search and non-linear techniques to directly and simultaneously fit Vcmax, Jmax, TPU, Rd and gm with the whole A,Cc curve in contrast to the conventional method, which fits Vcmax, Rd or gm first and then solves for Vcmax, Jmax and/or TPU with Vcmax, Rd and/or gm held as constants. [source]

    Temperature responses are a window to the physiology of dark respiration: differences between CO2 release and O2 reduction shed light on energy conservation

    PLANT CELL & ENVIRONMENT, Issue 7 2008
    JÖRG KRUSE
    ABSTRACT We showed that temperature responses of dark respiration for foliage of Pinus radiata could be approximated by Arrhenius kinetics, whereby E0 determines shape of the exponential response and denotes overall activation energy of respiratory metabolism. Reproducible and predictable deviation from strict Arrhenius kinetics depended on foliage age, and differed between RCO2 and RO2. Inhibition of oxygen reduction (RO2) by cyanide (inhibiting COX) or SHAM (inhibiting AOX) resulted in reproducible changes of the temperature sensitivity for RO2, but did not affect RCO2. Enthalpic growth , preservation of electrons in anabolic products , could be approximated with knowledge of four variables: activation energies (E0) for both RCO2 and RO2, and basal rates of respiration at a low reference temperature (RREF). Rates of enthalpic growth by P. radiata needles were large in spring due to differences between RREF of oxidative decarboxylation and that of oxygen reduction, while overall activation energies for the two processes were similar. Later during needle development, enthalpic growth was dependent on differences between E0 for RCO2 as compared with RO2, and increased E0(RO2) indicated greater contributions of cytochrome oxidase to accompany the switch from carbohydrate sink to source. Temperature-dependent increments in stored energy can be calculated as the difference between RCO2,HCO2 and RO2,HO2. [source]

    Assessing the relationship between respiratory acclimation to the cold and photosystem II redox poise in Arabidopsis thaliana

    PLANT CELL & ENVIRONMENT, Issue 12 2007
    ANNA F. ARMSTRONG
    ABSTRACT We examined the effect of manipulating photosystem II (PSII) redox poise on respiratory flux in leaves of Arabidopsis thaliana. Measurements were made on wild-type (WT) plants and npq4 mutant plants deficient in non-photochemical quenching (NPQ). Two experiments were carried out. In the first experiment, WT and mutant warm-grown plants were exposed to three different irradiance regimes [75, 150 and 300 µmol photosynthetically active radiation (PAR)], and leaf dark respiration was measured in conjunction with PSII redox poise. In the second experiment, WT and mutant warm-grown plants were shifted to 5 °C and 75, 150 or 300 µmol PAR, and dark respiration was measured alongside PSII redox poise in cold-treated and cold-developed leaves. Despite significant differences in PSII redox poise between genotypes and irradiance treatments, neither genotype nor growth irradiance had any effect upon the rate of respiration in warm-grown, cold-treated or cold-developed leaves. We conclude that changes in PSII redox poise, at least within the range experienced here, have no direct impacts on rates of leaf dark respiration, and that the respiratory cold acclimation response is unrelated to changes in chloroplast redox poise. [source]

    Atmospheric CO2 concentration does not directly affect leaf respiration in bean or poplar

    PLANT CELL & ENVIRONMENT, Issue 11 2001
    S. Jahnke
    Abstract It is a matter of debate if there is a direct (short-term) effect of elevated atmospheric CO2 concentration (Ca) on plant respiration in the dark. When Ca doubles, some authors found no (or only minor) changes in dark respiration, whereas most studies suggest a respiratory inhibition of 15,20%. The present study shows that the measurement artefacts , particularly leaks between leaf chamber gaskets and leaf surface, CO2 memory and leakage effects of gas exchange systems as well as the water vapour (,water dilution') effect on DCO2 measurement caused by transpiration , may result in larger errors than generally discussed. A gas exchange system that was used in three different ways , as a closed system in which Ca increased continuously from 200 to 4200 mmol (CO2) mol -1 (air) due to respiration of the enclosed leaf; as an intermittently closed system that was repeatedly closed and opened during Ca periods of either 350 or 2000 mmol mol -1, and as an open system in which Ca varied between 350 and 2000 mmol mol -1, is described. In control experiments (with an empty leaf chamber), the respective system characteristics were evaluated carefully. When all relevant system parameters were taken into account, no effects of short-term changes in CO2 on dark CO2 efflux of bean and poplar leaves were found, even when Ca increased to 4200 mmol mol -1. It is concluded that the leaf respiration of bean and poplar is not directly inhibited by elevated atmospheric CO2. [source]

    Direct and indirect effects of elevated CO2 on leaf respiration in a forest ecosystem

    PLANT CELL & ENVIRONMENT, Issue 9 2001
    J. G. Hamilton
    Abstract We measured the short-term direct and long-term indirect effects of elevated CO2 on leaf dark respiration of loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua) in an intact forest ecosystem. Trees were exposed to ambient or ambient + 200 µmol mol,1 atmospheric CO2 using free-air carbon dioxide enrichment (FACE) technology. After correcting for measurement artefacts, a short-term 200 µmol mol,1 increase in CO2 reduced leaf respiration by 7,14% for sweetgum and had essentially no effect on loblolly pine. This direct suppression of respiration was independent of the CO2 concentration under which the trees were grown. Growth under elevated CO2 did not appear to have any long-term indirect effects on leaf maintenance respiration rates or the response of respiration to changes in temperature (Q10, R0). Also, we found no relationship between mass-based respiration rates and leaf total nitrogen concentrations. Leaf construction costs were unaffected by growth CO2 concentration, although leaf construction respiration decreased at elevated CO2 in both species for leaves at the top of the canopy. We conclude that elevated CO2 has little effect on leaf tissue respiration, and that the influence of elevated CO2 on plant respiratory carbon flux is primarily through increased biomass. [source]

    Acclimation of snow gum (Eucalyptus pauciflora) leaf respiration to seasonal and diurnal variations in temperature: the importance of changes in the capacity and temperature sensitivity of respiration

    PLANT CELL & ENVIRONMENT, Issue 1 2000
    O. K. Atkin
    ABSTRACT We investigated the relationship between daily and seasonal temperature variation and dark respiratory CO2 release by leaves of snow gum (Eucalyptus pauciflora Sieb. ex Spreng) that were grown in their natural habitat or under controlled-environment conditions. The open grassland field site in SE Australia was characterized by large seasonal and diurnal changes in air temperature. On each measurement day, leaf respiration rates in darkness were measured in situ at 2,3 h intervals over a 24 h period, with measurements being conducted at the ambient leaf temperature. The rate of respiration at a set measuring temperature (i.e. apparent ,respiratory capacity') was greater in seedlings grown under low average daily temperatures (i.e. acclimation occurred), both in the field and under controlled-environment conditions. The sensitivity of leaf respiration to diurnal changes in temperature (i.e. the Q10 of leaf respiration) exhibited little seasonal variation over much of the year. However, Q10 values were significantly greater on cold winter days (i.e. when daily average and minimum air temperatures were below 6° and ,1 °C, respectively). These differences in Q10 values were not due to bias arizing from the contrasting daily temperature amplitudes in winter and summer, as the Q10 of leaf respiration was constant over a wide temperature range in short-term experiments. Due to the higher Q10 values in winter, there was less difference between winter and summer leaf respiration rates measured at 5 °C than at 25 °C. The net result of these changes was that there was relatively little difference in total daily leaf respiratory CO2 release per unit leaf dry mass in winter and summer. Under controlled-environment conditions, acclimation of respiration to growth temperature occurred in as little as 1,3 d. Acclimation was associated with a change in the concentration of soluble sugars under controlled conditions, but not in the field. Our data suggest that acclimation in the field may be associated with the onset of cold-induced photo-inhibition. We conclude that cold-acclimation of dark respiration in snow gum leaves is characterized by changes in both the temperature sensitivity and apparent ,capacity' of the respiratory apparatus, and that such changes will have an important impact on the carbon economy of snow gum plants. [source]

    Changes in 13C/12C of oil palm leaves to understand carbon use during their passage from heterotrophy to autotrophy,

    RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2009
    Emmanuelle Lamade
    The carbon isotope composition of leaf bulk organic matter was determined on the tropical tree Elaeis guineensis Jacq. (oil palm) in North Sumatra (Indonesia) to get a better understanding of the changes in carbon metabolism during the passage from heterotrophy to autotrophy of the leaves. Leaf soluble sugar (sucrose, glucose and fructose) contents, stomatal conductance and dark respiration, as well as leaf chlorophyll and nitrogen contents, were also investigated. Different growing stages were sampled from leaf rank ,6 to rank 57. The mean values for the ,13C of bulk organic matter were ,29.01,±,0.9, for the leaflets during the autotrophic stage, ,27.87,±,1.08, for the petioles and ,28.17,±,1.09, for the rachises, which are in the range of expected values for a C3 plant. The differences in ,13C among leaf ranks clearly revealed the changes in the origin of the carbon source used for leaf growth. Leaves were 13C-enriched at ranks below zero (around ,27,). During this period, the ,spear' leaves were completely heterotrophic and reserves from storage organs were mobilised for the growth of these young emerging leaves. 13C-depletion was then observed when the leaf was expanding at rank 1, and there was a continuous decrease during the progressive passage from heterotrophy until reaching full autotrophy. Thereafter, the ,13C remained more or less constant at around ,29.5,. Changes in sugar content and in ,13C related to leaf ranks showed an interesting similarity of the passage from heterotrophy to autotrophy of oil palm leaves to the budburst of some temperate trees or seed germination reported in the literature. Copyright © 2009 John Wiley & Sons, Ltd. [source]