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1.
The dose- and time-response effects of sequential 3 h+3 h NO→NO2 day time exposures [0–9 μl l?1 (ppm) NO, 0–7.5 μl l?1 NO2] followed by 3 h+3 h NO→NO2 night-time exposures (0–9.5 μl l?1 NO, 0–9 μl l?1 NO2) on photosynthesis, transpiration and dark respiration were examined for nine Carpatho-Ukrainian (‘Rachovo’) half-sib families and for two populations, one from the FRG (‘Westerhof’) and one from the GDR (‘Schmiedefeld’) of Norway spruce [Picea abies (L.) Karst.], all in their 4th growing season. In a second exposure series the exposure sequence was reversed. None of the treatments induced needle scorching. The higher NOx (NO or NO2) concentrations reduced photosynthesis and transpiration within 1 h. The physiology of the different spruce types was affected significantly differently, the most sensitive spruce having its photosynthesis suppressed 6.6 times and its transpiration 5.5 times more than the most tolerant. ‘Westerhof’ was more sensitive to NO2 than the average ‘Rachovo’ half-sibs. The gradients of different photosynthesis and transpiration sensitivities among the half-sibs (and ‘Westerhof’) demonstrated a significant, positive, mutual correlation, but significant negative correlations with the gradient of novel decline symptoms among their parents growing in Danish forests. The relative photosynthesis and transpiration sensitivies may thus serve as diagnostic parameters for laboratory selection of the most resistant trees to novel spruce decline. The average NO2 flux density was three times larger than the average NO flux density. Only for NO2 and in light was stomatal NOx uptake larger than the total NOx uptake. Both night transpiration and dark respiration were stimulated by high concentrations of night NOx, preceded by day NOx exposures. 相似文献
2.
The dose- and time-response effects of single 4 h day-time exposures of 0.064, 0.166, 0.336, 0.452 or 0.693 μl l?1 (ppm) O3 followed by single 4 h night-time exposures of 0.078, 0.198, 0.378, 0.502 or 0.747 μl l?1 O3 on photosynthesis, transpiration and dark respiration were examined for nine Carpatho-Ukrainian (‘Rachovo’) half-sib families and for two populations. ‘Westerhof’ from the FRG and ‘Schmiedefeld’ from the GDR, of Norway spruce [Picea abies (L.) Karst.], all in their 4th growing season. Needles were scorched by 4 h exposures to 0.336 μl l?1 O3 and higher. The lag before photosynthesis and transpiration responded significantly to O3 decline took from a few minutes at the highest concentration to several hours at the lower concentrations. Recovery of photosynthesis and transpiration was absent or extremely slow. Photosynthesis of the different spruce types was affected significantly differently, the most sensitive spruce having its photosynthesis suppressed 1.9 times and its transpiration 1.6 times more than the most tolerant spruce. The physiological responses of ‘Westerhof’ were less sensitive than the average ‘Rachovo’ half-sibs. Neither night transpiration nor dark respiration were affected by high doses of night O3, preceded by day O3 exposures. The gradients of different photosynthesis and transpiration sensitivities of the young half-sibs (and ‘Westerhof’) demonstrated a significant, positive, mutual correlation, and significant positive correlations with the gradient of novel decline symptoms of their parents growing in Danish forests. The relative photosynthesis and transpiration sensitivities may thus serve as diagnostic parameters in laboratory tests for selection against novel spruce decline. 相似文献
3.
Henrik Saxe 《Physiologia plantarum》1989,76(3):362-367
The dose- and time-response effects of 3 days of 6 h day-time sequential exposures to NO2 , SO2 and SO2 +NO2 of 0.45–1.81 μl l−1 (ppm) SO2 and 1.50–7.65 μl l−1 NO2 on photosynthesis, transpiration and dark respiration were examined for nine Carpatho-Ukrainian half-sib families and a population from the GFR ('Westerhof') of Norway spruce [ Piecea abies (L.) Karst.], all in their 5th growing season.
SO2 +NO2 inhibited photosynthesis and transpiration and stimulated dark respiration more than SO2 alone. SO2 and SO2 +NO2 at the lowest concentrations inhibited night transpiration, but increased it at the highest concentration, the strongest effects being obtained with combined exposures. Photosynthesis of the different half-sib families was affected significantly differently by SO2 +NO2 exposures. NO2 alone had no effects.
Sensitivity to transpiration decline correlated negatively with branch density. Height of trees correlated postitively with decline sensitivity in the seed orchard. The distribution of photosynthesis and transpiration sensitivities over all tested half-sib families correlated negatively with the distribution of decline sensitivity of their parents in a rural Danish seed orchard. The relative photosynthesis and transpiration sensitivities may thus serve as diagnostic parameters for selecting against novel spruce decline. 相似文献
SO
Sensitivity to transpiration decline correlated negatively with branch density. Height of trees correlated postitively with decline sensitivity in the seed orchard. The distribution of photosynthesis and transpiration sensitivities over all tested half-sib families correlated negatively with the distribution of decline sensitivity of their parents in a rural Danish seed orchard. The relative photosynthesis and transpiration sensitivities may thus serve as diagnostic parameters for selecting against novel spruce decline. 相似文献
4.
STEFAN SLOVIK 《Global Change Biology》1996,2(5):459-477
Field data on the sulphur and cation budget of growing Norway spruce canopies (Picea abies [L.] Karst.) are summarized. They are used to test a spruce decline model capable of quantifying effects of chronic SO2 pollution on spruce forests. At ambient SO2 concentrations, acute SO2 damage is rare, but exposure to polluted air produces reversible thinning of the canopy structure with a half-time of a few years. Canopy thinning in the spruce decline model is highest (i) at elevated SO2 pollution, (ii) in the mountains, (iii) at unfertilized sites with poor K+, Mg2+ or Zn2+ supply, (iv) at low spruce litter decomposition rates, and (v) acidic, shallow soils at high annual precipitation rates in the field and vice versa. Model application using field data from Würzburg (moderate SO2 pollution, alkaline soils, no spruce decline) and from the Erzgebirge (extreme SO2 pollution, acidic soils in the mountains, massive spruce decline) predicts canopy thinning by 2–11% in Würzburg and by 45–70% in the Erzgebirge. The model also predicts different SO2-tolerance limits for Norway spruce depending on the site elevation and on the nutritional status of the needles. If needle loss of more than 25% (damage class 2) is taken to indicate ‘real damage’ exceeding natural variances, then for optimum soil conditions SO2 tolerance limits range from (27.3 ± 7.4) μg m?3 to (62.6 ± 16.5) μg m?3. For shallow and acidic soils, SO2 tolerance limits range from (22.0 ± 5.5) μg m?3 to (37.4 ± 7.5) μ m?3. These tolerance limits, which are calculated on an ecophysiological data basis for Norway spruce are close to epidemiological SO2-toIerance limits as recommended by the IUFRO, UN-ECE and WHO. The observed statistical regression slope of the plot (damaged spruce trees vs. SO2-pollution) in west Germany is confirmed by modelling (6% error). Model application to other forest trees allows deduction of the observed sequence of SO2-sensitivity: Abies > Picea > Pinus > Fagus > Quercus. Thus, acute phytotoxicity of SO2 seems not to be involved in ‘forest decline’. Chronic SO2-pollution induces massive canopy thinning of Abies alba and Picea abies only at unfavourable sites, where natural stress factors and secondary effects of SO2pollution act together to produce tree decline. 相似文献
5.
STEFAN SLOVIK 《Global Change Biology》1996,2(5):443-458
Regarding time ranges of years, a rationale has been developed which is capable of explaining observed ‘spruce decline’ symptoms observed when spruce is exposed to air containing ambient levels of SO2. It integrates and interrelates (i) ecophysiological data (tree morphology, assimilate partitioning, canopy turnover, senescence physiology, stomatal conductance, canopy throughfall, sulphur metabolism, tonoplast symport), (ii) pedological data (soil leaching, cation recycling, litter decomposition, forest nutrition), and (iii) meteorological data (site elevation, length of the annual trunk growth period, SO2-pollution). Furthermore, it can explain field observations at numerous sites of spruce decline in central Europe where SO2 is implicated as a factor of forest decline: (i) thinning of the canopy structure; (ii) early needle senescence; (iii) cation deficiency; (iv) low SO2 tolerance at sites with depleted soils in the mountains; (v) synergism of SO2pollution and acidic precipitation; (vi) recovery after liming, fertilization and after decreasing SO2 pollution; and (vii) higher SO2 tolerances of deciduous angiosperms. Different SO2tolerance strategies are identified that are employed by more SO2-tolerant tree species. Ecophysiological SO2tolerance factors interact in a complex synergistic or antagonistic manner. It is concluded that chronic SO2 pollution at ambient concentrations predisposes mainly evergreen gymnosperms to suffer under synergistic environmental stresses (frost, drought, pathogens, etc.). Thinning of the crown structure is massive at extreme sites, where several stresses act simultaneously on the trees (depleted soils, high SO2 pollution, acidic rain, etc.). Mathematical formulations allow precise definitions of terms such as cooperativity, synergism, antagonism, vitality, predisposition, latency, etc. This universal rationale, which is applicable to all tree species, is exemplified here for Norway spruce (Picea abies [L.] Karst.). Integration of parameters yields an ordinary differential equation, which can be solved analytically. It predicts reversible dynamics of crown structures and gives an ecophysiological background to‘damage’. 相似文献
6.
Gross primary productivity and transpiration flux of the Australian vegetation from 1788 to 1988 AD: effects of CO2 and land use change 总被引:2,自引:0,他引:2
We present a novel approach to estimating the transpiration flux and gross primary productivity (GPP) from Normalized Difference Vegetation Index, leaf functional types, and readily available climate data. We use this approach to explore the impact of variations in the concentration of carbon dioxide in the atmosphere ([CO2]) and consequent predicted changes in vegetation cover, on the transpiration flux and GPP. There was a near 1 : 1 relationship between GPP estimated with this transpiration flux approach and that estimated using a radiation‐use efficiency (RUE) approach. Model estimates are presented for the Australian continent under three vegetation–[CO2] scenarios: the present vegetation and hypothetical ‘natural’ vegetation cover with atmospheric CO2 concentration ([CO2]) of 350 μmol mol?1 (pveg350 and nveg350), and for the ‘natural’ vegetation with [CO2] 280 μmol mol?1 (nveg280). Estimated continental GPP is 6.5, 6.3 and 4.3 Gt C yr?1 for pveg350, nveg350 and nveg280, respectively. The corresponding transpiration fluxes are 232, 224 and 190 mm H2O yr?1. The contribution of the raingreen and evergreen components of the canopy to these fluxes are also estimated. 相似文献
7.
The ambient pollution climate at the Liphook forest fumigation site, where coniferous trees were fumigated with SO2 and O3, for 4 years under field conditions, was characteristic of the fringes of the areas where pollutant effects are a problem. Experimental treatments increased SO2 concentrations to levels more characteristic of Eastern Europe, and summer O3 concentrations by 30%. Deposition of SO2 to the soil between the trees (inferred from shallow lysimeters) was significant, the deposition velocity being 2–1 mms?1. Deposition to Scots pine and Sitka spruce canopies was greater, deposition velocities being 8.5 and 9.4 mm s?1, respectively. These high values may perhaps be explained by co-deposition with NH3. Calculations assume that dry deposition was the sole source of SO42? gain in throughfall, and that there was no significant retention by the trees. There was a trend for O3 to enhance SO2 deposition to both soil and trees. Fumigation with SO2 led to a significant increase in leaching of cations from foliage. Each species neutralized about 63% of the dry-deposited SO2, predominantly by ion exchange for Ca and K. Equations are provided which allow calculation of foliar leaching given SO2 concentrations or SO42? deposition. Fumigation increased the rate of nutrient cycling considerably, without affecting foliar concentrations or damaging the trees. Ozone treatments did not enhance foliar leaching, calling into question some suggested mechanisms for the causes of forest decline. 相似文献
8.
Ion contents in needles from Norway spruce trees [Picea abies (L.) Karst.] growing in Würzburg and in the SO2-polluted Erzgebirge mountains were analysed to quantify cations which accumulate together with sulphate. In Würzburg there was a positive correlation of potassium (0.680 ± 0.300 Eq Eq?1 SO4?2), magnesium (0.415 ± 0.111 Eq Eq?1 SO4?2) and zinc (0.059 ± 0.006 Eq Eq?1 SO42?). In the Erzgebirge, potassium was also the stoichiometrically most important cation (0–887 ± 0–180 Eq K+ Eq?1 SO42?). All other correlations examined were weak or statistically non-significant. At both sites the calcium content of spruce needles did not depend on the sulphate content. The lack of a role for Ca2+ in neutralizing sulphate is a consequence of the presence of free oxalic acid in needles. Soluble oxalic acid precipitates Ca2+, which thereby becomes unavailable as a counterion for SO42?. The activity coefficients of Ca2+ and oxalate2?, and the solubility product of Ca-oxalate, were determined from in vivo data. It is concluded that the chronic accumulation of atmospheric sulphate in spruce needle vacuoles depletes available potassium and thereby strongly interferes with spruce growth and canopy turnover. This leads to impaired spruce vitality, even at sites where acute SO2 disease symptoms are absent. 相似文献
9.
Barton D. Clinton Chris A. Maier Chelcy R. Ford Robert J. Mitchell 《Trees - Structure and Function》2011,25(6):997-1007
In 20-year-old longleaf pine, we examined short-term effects of reduced live leaf area (A
L) via canopy scorching on sap flow (Q; kg H2O h−1), transpiration per unit leaf area (E
L; mm day−1), stem CO2 efflux (R
stem; μmol m−2 s−1) and soil CO2 efflux (R
soil; μmol m−2 s−1) over a 2-week period during early summer. R
stem and Q were measured at two positions (1.3-m or BH, and base of live crown—BLC), and R
soil was measured using 15 open-system chambers on each plot. E
L before and after treatment was estimated using Q measured at BLC with estimates of A
L before and after scorching. We expected Q to decrease in scorched trees compared with controls resulting from reduced A
L. We expected R
stem at BLC and BH and R
soil to decrease following scorching due to reduced leaf area, which would decrease carbon supply to the stem and roots. Scorching
reduced A
L by 77%. Prior to scorching, Q at BH was similar between scorch and control trees. Following scorching, Q was not different between control and scorch trees; however, E
L increased immediately following scorching by 3.5-fold compared to control trees. Changes in E
L in scorched trees corresponded well with changes in VPD (D), whereas control trees appeared more decoupled over the 5-day period following treatment. By the end of the study, R
stem decreased to 15–25% in scorched trees at both stem positions compared to control trees. Last, we found that scorching resulted
in a delayed and temporary increase in R
soil rather than a decrease. No change in Q and increased E
L following scorching indicates a substantial adjustment in stomatal conductance in scorched trees. Divergence in R
stem between scorch and control trees suggests a gradual decline in stem carbohydrates following scorching. The absence of a strong
R
soil response is likely due to non-limiting supplies of root starch during early summer. 相似文献
10.
Slovik Stefan Siegmund Alfred Kindermann Gerald Riebeling Rüdiger Balázs Árpad 《Plant and Soil》1995,(1):405-419
Monthly uptake rates and the annual deposition of gaseous SO2 via the stomata of six Norway spruce canopies (Picea abies (L.) Karst.) in Germany (Königstein im Taunus, Witzenhausen, Grebenau, Frankenberg, Spessart, Fürth im Odenwald) were calculated (i) from statistical response functions of stomatal aperture depending on meteorological data, and (ii) from the synchronously measured SO2 immission at these stands. The stomatal response functions had been derived on the basis of thorough stomatal water conductance measurements in the field. Calculations of the SO2 conductance of spruce twigs and SO2 uptake rates via stomata need continuously measured complete data sets of the (i) light intensity, (ii) air temperature, (iii) air humidity and (iv) SO2 concentration in spruce forests from all the year. These data were recorded half hourly in different German spruce forests. The apparent needle water vapour pressure difference and transpiration rates were calculated from meteorological data. Additional use of canopy through flow data in dry years allowed the estimation of the mean stomatal conductance for H2O and SO2 of whole spruce canopies. The annual SO2 uptake of a mean unit needle surface in spruce forests was 32% of the SO2 uptake rate of exposed needles at the top of spruce crowns. There is significant SO2 uptake all the year. The mean SO2 dose at all sites and years received through the stomata was (0.25±0.07) mol SO2 m-2 (total needle surface) (nPa Pa-1)-1 (annual mean of SO2 immission; 1 nPa (SO2) Pa-1 (air) = 1 ppb) day-1 (vegetation period per year). Comparison of calculated SO2 uptake rates into needles with measured SO4
2- accumulation rates in needles from the mentioned sites and additionally from Würzburg, Schneeberg (Fichtelgebirge) and from three sites in the eastern Erzgebirge (Höckendorf, Kahleberg, Oberbärenburg) revealed that oxidative SO2 detoxification (SO4
2- formation) dominates only at sites with high SO2 immission and short vegetation periods. Under these conditions 70 to 90% of the annual stomatal SO2 uptake is detoxified via SO4
2- accumulation in needles. Cations are needed for neutralization of accumulating SO4
2- which are inavailable to support growth. Thus, SO2 induces a dominant and competitive additional nutrient cation demand, cation deficiency symptoms and enhanced needle loss (spruce decline symptoms) mainly at sites, where the ratio R=(SO2 immission): (length of the vegetation period) is higher than R=0.07 nPa Pa-1 day-1. Correlation analysis of the relative needle loss versus the SO2-dependent SO4
2- formation rate revealed a significant increase of needle loss at the 98% level (Student). At sites with small SO2 immission and long vegetation periods (R<0.07 nPa Pa-1 day-1) reductive SO2 detoxification via growth (and/or phloem export of SO4
2-) is not kinetically overburdened. Under these conditions only 30% of the annual SO2 uptake is detoxified via SO4
2- formation and spruce decline is small or absent. On the basis of the critical value R0.07 nPa Pa-1 day-1 recommended SO2 immission limits can be deduced on a mere ecophysiological basis. These deduced values are close to the proposed SO2 immission limits of the IUFRO, WHO and the UNECE. 相似文献
11.
Silvia Anselmi‡ Marta Chiesi† Monica Giannini‡ Fausto Manes‡ Fabio Maselli† 《Global Ecology and Biogeography》2004,13(4):371-380
Aim This paper investigates the use of an ecosystem simulation model, FOREST‐BGC, to estimate the main ecophysiological processes (transpiration and photosynthesis) of Mediterranean coastal forest areas using remotely sensed data. Location Model testing was carried out at two protected forest sites in central Italy, one of which was covered by Turkey oak (Circeo National Park) and the other by holm‐oak (Castelporziano Estate). Methods At both sites, transpiration and photosynthesis measurements were collected in the field during the growing seasons over a four‐year period (1999 and 2001 for the Turkey oak; 1997, 1999 and 2000 for the holm‐oak). Calibration of the model was obtained through combining information derived from ground measurements and remotely sensed data. In particular, remote sensing estimates of the Leaf Area Index derived from 1 × 1‐km NOAA AVHRR Normalized Difference Vegetation Index data were used to improve the adaptation of the model to local forest conditions. Results The results indicated different strategies regarding water use efficiency, ‘water spending’ for Turkey oak and ‘water saving’ for holm‐oak. The water use efficiency for the holm‐oak was consistently higher than that for the Turkey oak and the relationship between VPD and WUE for the holm‐oak showed a higher coefficient of determination (R2 = 0.9238). Comparisons made between the field measurements of transpiration and photosynthesis and the model estimates showed that the integration procedure used for the deciduous oak forest was effective, but that there is a need for further studies regarding the sclerophyllous evergreen forest. In particular, for Turkey oak the simulations of transpiration yielded very good results, with errors lower than 0.3 mm H2O/day, while the simulation accuracy for photosynthesis was lower. In the case of holm‐oak, transpiration was markedly overestimated for all days considered, while the simulations of photosynthesis were very accurate. Main conclusions Overall, the approach offers interesting operational possibilities for the monitoring of Mediterranean forest ecosystems, particularly in view of the availability of new satellite sensors with a higher spatial and temporal resolution, which have been launched in recent years. 相似文献
12.
Responses of tomato leaves in a greenhouse to light and CO2 were examined at the transient stage at the end of winter, when both photoperiod and irradiance gradually increase. Additionally, CO2 fluxes were calculated for a greenhouse without supplementary lighting and without CO2 enrichment based on CO2 sinks (plant photosynthesis) and CO2 sources (plant and substrate respiration). In January, tomato leaves in the greenhouse showed low photosynthesis with a maximum assimilation of 6–8 μmol CO2 m−2 s−1, a quantum yield of 0.06 μmol CO2 μmol−1 photosynthetic active radiation (PAR) and a low light compensation point of 26 μmol PAR m−2 s−1, a combination which classifies them as shade leaves. In February, tomato leaves increased their light compensation point to 39 μmol PAR m−2 s−1 and quantum yield to 0.08, the former indicating the adaptation to increased irradiance and photoperiod. These tomato leaves increased their transpiration from 0.4 to 0.9 in January to ∼2 mmol H2O m−2 s−1 in February. Both photosynthesis and transpiration were primarily limited by light but neither by stomatal conductivity nor by CO2. In January, light response of photosynthesis, dark respiration and transpiration were negligibly affected by increasing CO2 concentrations from 600 to 900 ppm CO2 under low light conditions, indicating no benefit of CO2 enrichment unless light intensity increased. In February, tomato leaves were photoinhibited at inherent greenhouse CO2 concentrations on the first sunny day; this photoinhibition was further enhanced by an increased CO2 concentration of 1000 ppm. CO2 fluxes in the greenhouse appeared strongly dependent on solar radiation. After exceeding the light compensation point in the morning, greenhouse CO2 concentrations decreased by 58 or by 110 ppm CO2 h−1 on a sunny day in January or February and by 23 ppm on overcast days in both months. Calculated per overall tomato canopy, plant photosynthesis contributed 42–50% to the morning CO2 depletion in the greenhouse. Dark respiration of tomato leaves was ∼2 μmol CO2 m−2 s−1 in January and ∼3 μmol CO2 m−2 s−1 in February. This dark respiration resulted in rises of 15 and 17 ppm CO2 h−1 at night in the greenhouse compartment and was identified as primary source of CO2. Respiration of the substrate used to grow the plants, which produced 7.3 ppm CO2 h−1, was identified as secondary source of CO2. The combined plant and substrate respiration resulted in peaks of up to 900 ppm CO2 in the greenhouse before dawn. 相似文献
13.
Two minuses can make a plus: waterlogging and elevated CO2 interactions in sweet cherry (Prunus avium) cultivars
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Margarita Pérez‐Jiménez María Hernández‐Munuera Maria Carmen Piñero Zapata Gregorio López‐Ortega Francisco M. del Amor 《Physiologia plantarum》2017,161(2):257-272
The increase in the ambient concentration of CO2 and other greenhouse gases is producing climate events that can compromise crop survival. However, high CO2 concentrations are sometimes able to mitigate certain stresses such as salinity or drought. In this experiment, the effects of waterlogging and CO2 are studied in combination to elucidate the eventual response in sweet cherry trees. For this purpose, four sweet cherry cultivars (‘Burlat’, ‘Cashmere’, ‘Lapins and ‘New Star’) were grafted on a typically hypoxia‐tolerant rootstock (Mariana 2624) and submitted to waterlogging for 7 days at either ambient CO2 concentration (400 µmol mol?1) or at elevated CO2 (800 µmol mol?1). Waterlogging affected plants drastically, by decreasing photosynthesis, stomatal conductance, transpiration, chlorophyll fluorescence and growth. It also brought about the accumulation of proline, chloride and sulfate. Nonetheless, raising the CO2 supply not only mitigated all these effects but also induced the accumulation of soluble sugars and starch in the leaf. Therefore, sweet cherry plants submitted to waterlogging were able to overcome this stress when grown in a CO2‐enriched environment. 相似文献
14.
The incorporation of 14C-leucine into the total-protein fraction of needles of Norway spruce (Picea abies [L.] Karst.) during short time incubation was used as a measure of protein synthesis in the light and in the dark. Light saturation curves, obtained for needles of different ages (new flush and 1 and 2 years old) or at different seasons (summer-winter) followed the Michaelis-Menten algorithm, exhibiting marked differences with regard to light saturation (Vmax) and the half-saturation constant (K5. 2). The light saturation curves of ATP level (mg g?1 fresh weight) and of leucine incorporation into protein (nmol mg?1 h?1) matched each other, suggesting that photophosphorylation may be decisive for the rate of protein synthesis in the light. This is confirmed by the action spectrum of leucine incorporation. which resembled an action spectrum of leaf photosynthesis, and also by partial inhibition of protein synthesis by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), an inhibitor of non-cyclic photophosphorylation. Light stimulated protein synthesis showed pronounced seasonal fluctuations with a summer maximum. Furmigation of 5 years old spruce trees for 3 months with SO2 in combination with O3 and/or NO2 caused a distinct enhancement of the protein synthesis rate in the light and, at a reduced absolute level, also in the dark. A similar result was obtained for 40 to 70 years old spruce stands when healthy and sick trees were compared: the latter being afflicted by the novel type of forest decline, which is characterized by yellowish bronze discolouration of sun-exposed older needles and partial loss of older needle generations (3 to 4 years old). The 1 year old needles of the unhealthy trees showed a markedly increased 14C-leucine incorporation rate which, in the dark, was even more pronounced than in the light. Stress-physiological mechanisms, which could possibly explain this stimulation, are discussed. 相似文献
15.
Summary CO2- and H2O-gas exchange of 20- to 25-year-old spruce trees from a plantation in the Hunsrück mountains were investigated over a period of 3 years. All measurements were made as pair comparisons, i.e., in each case the gas exchange of a damaged tree and of a relatively healthy tree in its immediate vicinity was measured simultaneously. A second plantation in the Westerwald mountains consisted of 18-year-old apparently healthy spruce trees. Pair comparison at this location meant comparison of two healthylooking trees. The investigations at both locations included diurnal course measurements of photosynthesis and transpiration, and light saturation curves and CO2-saturation curves of photosynthesis. The reduced photosynthesis parameters of the phenotypically damaged trees at the Hunsrück location indicates massive damage to the photosynthetic apparatus. Measurements of H2O-gas exchange showed that there are disturbances in stomatal regulation of the needles of damaged trees. As a result, the water use efficiency of these needles proved to be significantly lower. In addition, apparent photorespiration of the damaged trees was decreased, whereas their light- and CO2-compensation points and their dark respiration were increased. In contrast to the Hunsrück plantation, no such effects were detectable when the healthy-looking Westerwald trees were subjected to pair comparison of gas exchange. Reduced photosynthetic capacity and disturbances of the stomatal regulation of the phenotypically damaged Hunsrück trees may be due to damage in the cellular membranes. Furthermore, a comparison of three growing seasons led to the conclusion that the gas exchange of spruce trees in their natural habitat is markedly influenced by climatic conditions. 相似文献
16.
A branch bag technique for simultaneous CO2 enrichment and assimilation measurements on beech (Fagus sylvatica L.) 总被引:7,自引:4,他引:3
A cheap CO2 enrichment system was designed to perform continuous gas exchange measurements of branches of mature European beech trees (Fagus sylvatica L.). Branches were grown at ambient (350 cm3 m-3) and elevated CO2 (700cm3 m-3) during the whole 1992 leafy period. Leaks resulting from airtightness defaults in the system appeared to be low enough to measure accurately net CO2 assimilation and transpiration rates during the day. However, the CO2 exchange rates during the night (respiration) were too low to allow accurate measurements. Elevated CO2 had a great effect on the net assimilation rate of branches via its influence on both the C3 photosynthetic pathway and the shade-tolerance of beech trees (85% increase). The A/Ca curves showed no acclimation effect to high CO2, both control and enriched branches increasing their net assimilation in the same way. The decrease of net assimilation rates in mature leaves was similar for both control and enriched branches. The pattern of daily transpiration rates remained the same for both control and enriched branches, hence we can assume that there was no visible CO2 effect on stomata. 相似文献
17.
Photosynthetic rate, transpiration rate and SO2 absorption rate were simultaneously measured under exposure to SO2 (0.1–1.0 μl l ?1) for 5 or 8 hr in six species belonging to C4 or C3 plants (Zea mays, Sorghum vulgare, Amaranthus tricolor, Oryza sativa, Avena sativa andHelianthus annuus). Distinct interspecific differences were found as to the extent of inhibition of photosynthetic rate. Calculation of diffusive resistance to H2O(r) and SO2(r′) showed that the ratio of r′/r was 1.9 irrespective of species and coincided well with the theoretical value based on molecular diffusion. Thus it was made clear that the absorption of SO2 was dependent upon the gas exchange capacity of leaf blade. Using the ratio of r′/r the rate of SO2 absorption could be calculated from transpiration rate and was compared with the inhibition rate of photosynthesis. In three C4 species, the inhibition of photosynthesis increased linearly with the amount of SO2 absorbed during a 5-hour period. The pattern of inhibition of photosynthesis inA. sativa andH. annuus among C3 species was similar to that of C4 species until the amount of SO2 absorbed reached 60 mg-SO2 m?2 above which the inhibition abruptly increased. The inhibition of photosynthesis inO. sativa was exceptionally severe even with only a small amount of SO2 absorbed. 相似文献
18.
A model that couples stomatal conductance, photosynthesis, leaf energy balance and transport of water through the soil–plant–atmosphere continuum is presented. Stomatal conductance in the model depends on light, temperature and intercellular CO2 concentration via photosynthesis and on leaf water potential, which in turn is a function of soil water potential, the rate of water flow through the soil and plant, and on xylem hydraulic resistance. Water transport from soil to roots is simulated through solution of Richards’ equation. The model captures the observed hysteresis in diurnal variations in stomatal conductance, assimilation rate and transpiration for plant canopies. Hysteresis arises because atmospheric demand for water from the leaves typically peaks in mid‐afternoon and because of uneven distribution of soil matric potentials with distance from the roots. Potentials at the root surfaces are lower than in the bulk soil, and once soil water supply starts to limit transpiration, root potentials are substantially less negative in the morning than in the afternoon. This leads to higher stomatal conductances, CO2 assimilation and transpiration in the morning compared to later in the day. Stomatal conductance is sensitive to soil and plant hydraulic properties and to root length density only after approximately 10 d of soil drying, when supply of water by the soil to the roots becomes limiting. High atmospheric demand causes transpiration rates, LE, to decline at a slightly higher soil water content, θs, than at low atmospheric demand, but all curves of LE versus θs fall on the same line when soil water supply limits transpiration. Stomatal conductance cannot be modelled in isolation, but must be fully coupled with models of photosynthesis/respiration and the transport of water from soil, through roots, stems and leaves to the atmosphere. 相似文献
19.
Kindermann Gerald Hüve Katja Slovik Stefan Lux Herbert Rennenberg Heinz 《Plant and Soil》1995,(1):421-423
The emission of reduced volatile sulfur compounds from twigs of Norway spruce (Picea abies (L.) Karst.) was measured in the field by cryosampling and gaschromatographic analysis. Trees were growing in the Erzgebirge (E-Germany) at Oberbärenburg and at the Kahleberg and at a third stand in NW-Bavaria (S-Germany). Emission rates were also measured for Scotch pine (Pinus sylvestris L.) and Blue spruce (Picea pungens Engelm.) at the Kahleberg. Twigs still attached to the trees were enclosed in a flow-through gas exchange cuvette. H2S was detected as the predominant reduced sulfur compound emitted from the twigs. The mean H2S emission rate from twigs of Norway spruce varied between 0.04 pmol kg-1 dw s-1 at Würzburg and 6.21 pmol kg-1 dw s-1 at the Kahleberg. Comparing different species at the Kahleberg, the mean H2S emission rate was almost the same from twigs of Norway spruce (6.2 pmol kg-1 dw s-1) and Blue Spruce trees (5.9 pmol kg-1 dw s-1) but it was approximately 18 times higher for Scotch pine (110 pmol kg-1 dw s-1). The percentage of SO2-exclusion via H2S-emission of the tree species investigated at the Kahleberg is calculated on the basis of data on SO2 fluxes. It is very small for Norway spruce and Blue spruce. However, for Scotch pine, H2S emission contributes about 10% to the detoxification of SO2. 相似文献
20.
The nature of the interaction between drought and elevated CO2 partial pressure (pCa) is critically important for the effects of global change on crops. Some crop models assume that the relative responses of transpiration and photosynthesis to soil water deficit are unaltered by elevated pCa, while others predict decreased sensitivity to drought at elevated pCa. These assumptions were tested by measuring canopy photosynthesis and transpiration in spring wheat (cv. Minaret) stands grown in boxes with 100 L rooting volume. Plants were grown under controlled environments with constant light (300 µmol m?2 s?1) at ambient (36 Pa) or elevated (68 Pa) pCa and were well watered throughout growth or had a controlled decline in soil water starting at ear emergence. Drought decreased final aboveground biomass (?15%) and grain yield (?19%) while elevated pCa increased biomass (+24%) and grain yield (+29%) and there was no significant interaction. Elevated pCa increased canopy photosynthesis by 15% on average for both water regimes and increased dark respiration per unit ground area in well‐watered plants, but not drought‐grown ones. Canopy transpiration and photosynthesis were decreased in drought‐grown plants relative to well‐watered plants after about 20–25 days from the start of the drought. Elevated pCa decreased transpiration only slightly during drought, but canopy photosynthesis continued to be stimulated so that net growth per unit water transpired increased by 21%. The effect of drought on canopy photosynthesis was not the consequence of a loss of photosynthetic capacity initially, as photosynthesis continued to be stimulated proportionately by a fixed increase in irradiance. Drought began to decrease canopy transpiration below a relative plant‐available soil water content of 0.6 and canopy photosynthesis and growth below 0.4. The shape of these responses were unaffected by pCa, supporting the simple assumption used in some models that they are independent of pCa. 相似文献