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1.
Patterns of genetic variation in gas-exchange physiology were analyzed in a 15-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation that contains 25 populations grown from seed collected from across the natural distribution of the species. Seed was collected from 33°30 to 53°12 north latitude and from 170 m to 2930 m above sea level, and from the coastal and interior (Rocky Mountain) varieties of the species. Carbon isotope discrimination () ranged from 19.70() to 22.43() and was closely related to geographic location of the seed source. The coastal variety (20.50 (SE=0.21)) was not significantly different from the interior variety (20.91 (0.15)). Instead, most variation was found within the interior variety; populations from the southern Rockies had the highest discrimination (21.53 (0.20)) (lowest water-use efficiency). Carbon isotope discrimination (), stomatal conductance to water vapor (g), the ratio of intercellular to ambient CO2 concentration (ci/ca), and intrinsic water-use efficiency (A/g) were all correlated with altitude of origin (r=0.76, 0.73, 0.74, and –0.63 respectively); all were statistically significant at the 0.01 level. The same variables were correlated with both height and diameter at age 15 (all at P0.0005). Observed patterns in the common garden did not conform to our expectation of higher WUE, measured by both A/g and , in trees from the drier habitats of the interior, nor did they agree with published in situ observations of decreasing g and with altitude. The genetic effect opposes the altitudinal one, leading to some degree of homeostasis in physiological characteri tics in situ. 相似文献
2.
3.
In a field rain-fed trial with 15 cassava cultivars, leaf gas exchanges and carbon isotope discrimination (Δ) of the same
leaves were determined to evaluate genotypic and within-canopy variations in these parameters. From 3 to 7 months after planting
leaf gas exchange was measured on attached leaves from upper, middle, and lower canopy layers. All gas exchange parameters
varied significantly among cultivars as well as canopy layers. Net photosynthetic rate (P
N) decreased from top canopy to bottom indicating both shade and leaf age effects. The same trend, but in reverse, was found
with respect to Δ, with the highest values in low canopy level and the lowest in upper canopy. There were very significant
correlations, with moderate and low values, among almost all these parameters, with P
N negatively associated with intercellular CO2 concentration (C
i), ratio of C
i to ambient CO2 concentration C
i/C
a, and Δ. Across all measured leaves, Δ correlated negatively with leaf water use efficiency (WUE = photosynthesis/stomatal
conductance, g
s) and with g
s, but positively with C
i and C
i/C
a. The later parameters negatively correlated with leaf WUE. Across cultivars, both P
N and correlated positively with storage root yield. These results are in agreement with trends predicted by the carbon isotope
discrimination model. 相似文献
4.
F. I. Woodward 《Oecologia》1986,70(4):580-586
Summary Observations have been made on the gas exchange and morphology of Vaccinium myrtillus taken from altitudes of 200 m, 610 m and 1,100 m along an altitudinal gradient in central Scotland. Under saturating irradiance, optimum temperatures and a range of vapour pressure deficits, photosynthetic rate and stomatal conductance increased with the altitude of origin of the populations. Correlated with these increases was an increase in the adaxial stomatal density with altitude. This response to altitude could be simulated in controlled conditions, by growing plants in a CO2 concentration below ambient, similar to that expected at altitude.Plant height decreased with altitude, a feature which was maintained in cultivation. Stem rigidity declined with altitude, in a manner which is predicted to limit the reproductive capacity of the population from 1,100 m in high wind speeds.Total leaf nitrogen increased with altitude. The nitrogen economy of the shoot is discussed in terms of nitrogen availability for stems and leaves and its control over maximum rates of photosynthesis, competitive ability and reproductive capacity. 相似文献
5.
Leaf gas exchange rates, predawn wp and daily minimum wm leaf water potentials were measured during a wet-to-dry season transition in pioneer (Jacaranda copaia, Goupia glabra andCarapa guianensis) and late stage rainforest tree species (Dicorynia guianensis andEperua falcata) growing in common conditions in artificial stands in French Guiana. Carbon isotope discrimination () was assessed by measuring the stable carbon isotope composition of the cellulose fraction of wood cores. The values were 2.7 higher in the pioneer species than in the late stage species. The calculated time integratedC
i values derived from the values averaged 281 mol mol–1 in the pioneers and 240 mol mol–1 in the late stage species. The corresponding time-integrated values of intrinsinc water-use efficiency [ratio CO2 assimilation rate (A)/leaf conductance (g)] ranged from 37 to 47 mmol mol–1 in the pioneers and the values were 64 and 74 mmol mol–1 for the two late stage species. The high values were associated—at least inJ. copaia—with high maximumg values and with high plant intrinsinc specific hydraulic conductance [Cg/(wm–wp], which could reflect a high competitive ability for water and nutrient uptake in the absence of soil drought in the pioneers. A further clear discriminating trait of the pioneer species was the very sensitive stomatal response to drought in the soil, which might be associated with a high vulnerability to cavitation in these species. From a methodological point of view, the results show the relevance of for distinguishing ecophysiological functional types among rainforest trees. 相似文献
6.
7.
Air pressure in leaf chambers is thought to affect gas exchange measurements through changes in partial pressure of the air components. However, other effects may come into play when homobaric leaves are measured in which internal lateral gas flow may occur. When there was no pressure difference between the leaf chamber and ambient air (DeltaP=0), it was found in previous work that lateral CO(2) diffusion could affect measurements performed with clamp-on leaf chambers. On the other hand, overpressure (DeltaP>0) in leaf chambers has been reported to minimize artefacts possibly caused by leaks in chamber sealing. In the present work, net CO(2) exchange rates (NCER) were measured under different DeltaP values (0.0-3.0 kPa) on heterobaric and homobaric leaves. In heterobaric leaves which have internal barriers for lateral gas movement, changes in DeltaP had no significant effect on NCER. For homobaric leaves, effects of DeltaP>0 on measured NCER were significant, obviously due to lateral gas flux inside the leaf mesophyll. The magnitude of the effect was largely defined by stomatal conductance; when stomata were widely open, the impact of DeltaP on measured NCER was up to 7 mumol CO(2) m(-2) s(-1) kPa(-1). Since many other factors are also involved, neither DeltaP=0 nor DeltaP>0 was found to be the 'one-size fits all' solution to avoid erroneous effects of lateral gas transport on measurements with clamp-on leaf chambers. 相似文献
8.
Effect of leaf structure and water status on carbon isotope discrimination in field-grown durum wheat 总被引:8,自引:0,他引:8
The relationships between leaf and kernel carbon isotope discriminations (Δ) and several leaf structural parameters that are indicators of photosynthetic capacity were studied in durum wheat grown in the field under three water regimens. A set of 144 genotypes were cultivated in two rain-fed trials, and 125 of these were grown under supplementary irrigation before heading. Total chlorophyll and nitrogen (N) contents, the dry mass per unit leaf area (LDM, the reciprocal of specific leaf area) and carbon isotope discrimination (Δ) were measured in penultimate leaves and Δ of mature kernels was also analysed. Both LDM and N per unit area showed significant (P≤ 0.001) negative correlation (r=–0.60 and r=–0.36, respectively) with leaf Δ in the wettest trial. Little or no correlation was found for any structural parameter and leaf Δ in the rain-fed trials. In contrast, in the two rain-fed trials LDM was the parameter with the strongest positive correlation (P≤ 0.001) with kernel Δ (r= 0.47 and 0.30) and grain yield (r= 0.43 and 0.29), whereas no correlation was found in the irrigation trial. These correlations, rather than representing a causal link between the amount of photosynthetic tissue and Δ, were probably indirect associations caused by a parallel effect of water status and phenology on leaf structure, grain Δ and yield. Correlations across trials (i.e. environments) between leaf structure and either Δ and yield were very high, although also spurious. Our results suggest that LDM should be used to cull segregating population differences in leaf Δ based on the internal photosynthetic capacity only in the absence of drought. Selecting for kernel Δ and grain yield on the basis of LDM is worthwhile for rain-fed trials. 相似文献
9.
Summary A thermocouple shows a high accuracy in reading temperatures, but it does not always give a true value for the temperature of the leaf against which it is pressed on. Temperature differences between the leaf and the air moving around it cause deviations of the shown temperature from the actual leaf temperature. A method is described to calibrate thermocouples inside gas exchange cuvettes without obstructing the movement of the air around the leaf, so that the heat exchange between thermocouple and air is taken into account. The reading of the leaf temperature in a steady-state porometer was checked by this method at various temperatures of ambient air (T
a
) and of the leaf (T
1
) and was found to give an average value of T
a
and T
1
. The effect of incorrect estimation of the leaf temperature on computed diffusive resistances on H2O (r
w
) and CO2 (r
c
) and intercellular CO2 partial pressures (p
i
c
) is discussed.Abbreviations
A
net CO2 uptake
-
E
evaporative transpiration
-
R
correlation coefficient
-
T
Temperature
-
a
heat-transfer coefficient
-
b
ratio of heat-transfer coefficients
-
q
heat transfer
-
p
c
CO2 partial pressure
-
p
w
H2O partial pressure
-
r
c
diffusive resistance on CO2
-
r
w
diff. resistance on H2O
-
a
ambient
-
i
intercellular
-
l
leaf
-
p
porometer
-
s
leaf surface (=boundary layer+stomata)
-
t
thermocouple; 1, 2: number of cuvette 相似文献
10.
The influence of water content and leaf anatomy on carbon isotope discrimination and photosynthesis in Sphagnum 总被引:2,自引:0,他引:2
The relative effect of diffusional resistance due to water films (rwf) and leaf anatomy (rp) on rates of net photosynthesis and on-line measures of carbon isotope discrimination (Δ=Δδ13C) was investigated in Sphagnum. Sphagnum species differ in the exposure of photosynthetic cells at the leaf surface. In S. affine, photosynthetic cells are widely exposed at the surface, whereas in S. magellanicum, photo-synthetic cells are enclosed within water-filled hyaline cells. This difference is expected to lead to variation in diffusive resistance within leaves (rp). Net photosynthesis and on-line Δ were measured at two water contents: greenhouse water content (wet) and blotted dry (dry). Without correcting for respiration, on-line Δ values differed significantly between wet (23.7%o) and dry (30.9%o) plants. However, there was no significant difference between species means and no species × water content interaction. Corrections for respiration lowered Δ values by approximately 8.1%o and reduced the mean difference to 3.1%o, but did not alter the rank order of treatments. Net photosynthesis also decreased by 16% in wet plants, but there was no significant difference between the two species. In addition, five populations of S. affine and S. magellanicum grown in a common garden were analysed for their organic matter carbon isotope composition (δ13C). These values varied more within each species (0.9–1.2%o) than between the two species (0.6%o). Therefore, we conclude that variation in surface water films leads to a greater difference in resistance to CO2 uptake and carbon isotope discrimination than that due to variation in leaf anatomical properties in Sphagnum. 相似文献
11.
Values (Δ(i)) predicted by a simplified photosynthetic discrimination model, based only on diffusion through air followed by carboxylation, are often used to infer ecological conditions from the 13C signature of plant organs (δ13C(p)). Recent studies showed that additional isotope discrimination (d that includes mesophyll conductance, photorespiration and day respiration, and post-carboxylation discrimination) can strongly affect δ13C(p); however, little is known about its variability during plant ontogeny for different species. Effect of ontogeny on leaf gas exchange rates, Δ(i) , observed discrimination (Δ(p)) and d in leaf, phloem and root of seven herbaceous species at three ontogenetic stages were investigated under controlled conditions. Functional group identity and ontogeny significantly affected Δ(i) and Δ(p). However, predicted Δ(i) did not match Δ(p). d, strongly affected by functional group identity and ontogeny, varied by up to 14 ‰. d scaled tightly with stomatal conductance, suggesting complex controls including changes in mesophyll conductance. The magnitude of the changes in δ13C(p) due to ontogeny was similar to that due to environmental factors reported in other studies. d and ontogeny should, therefore, be considered in ecosystem studies, integrated in ecosystem models using δ13C(p) and limit the applicability of δ13C(leaf) as a proxy for water-use efficiency in herbaceous plants. 相似文献
12.
Short-term changes in leaf carbon isotope discrimination in salt- and water-stressed c(4) grasses 总被引:1,自引:5,他引:1
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Online carbon isotope discrimination (Δ) and leaf gas exchange measurements were made with control and salt-stressed Zea mays and Andropogon glomeratus, two NADP-ME type C4 grasses. Linear relationships between Δ and pi/pa (the ratio of intercellular to atmospheric CO2 partial pressure) were found for control plants which agreed well with theoretical models describing carbon isotope discrimination in C4 plants. These data provided estimates of , the proportion of CO2 fixed by phosphoenolpyruvate carboxylase which leaks out of the bundle sheath and the component of fractionation due to diffusion in air. Salt-stressed plants had wider variation in Δ for the same or less range in pi/pa. Additional work indicated Δ changed independently of pi/pa in both water- and salt-stressed plants, suggesting a possible diurnal change in as plant water status changed linked to a decrease in the activity of the C3 photosynthetic pathway relative to C4 pathway activity. The possible effect of stress-induced changes in on organic matter δ13 C of C4 plants is apt to be most apparent in chronically stressed environments. 相似文献
13.
Spatial distribution of leaf water-use efficiency and carbon isotope discrimination within an isolated tree crown 总被引:11,自引:5,他引:6
X. Le Roux T. Bariac H. Sinoquet B. Genty C. Piel A. Mariotti C. Girardin & P. Richard 《Plant, cell & environment》2001,24(10):1021-1032
The spatial variations in the stable carbon isotope composition (δ13C) of air and leaves (total matter and soluble sugars) were quantified within the crown of a well‐watered, 20‐year‐old walnut tree growing in a low‐density orchard. The observed leaf carbon isotope discrimination (Δ) was compared with that computed by a three‐dimensional model simulating the intracanopy distribution of irradiance, transpiration and photosynthesis (previously parameterized and tested for the same tree canopy) coupled to a biophysically based model of carbon isotope discrimination. The importance of discrimination associated with CO2 gradients encountered from the substomatal sites to the carboxylation sites was evaluated. We also assessed by simulation the effect of current irradiance on leaf gas exchange and the effect of long‐term acclimation of photosynthetic capacity and stomatal and internal conductances to light regime on intracanopy gradients in Δ. The main conclusions of this study are: (i) leaf Δ can exhibit important variations (5 and 8‰ in total leaf material and soluble sugars, respectively) along light gradients within the foliage of an isolated tree; (ii) internal conductance must be taken into account to adequately predict leaf Δ, and (iii) the spatial variations in Δ and water‐use efficiency resulted from the short‐term response of leaf gas exchange to variations in local irradiance and, to a much lesser extent, from the long‐term acclimation of leaf characteristics to the local light regime. 相似文献
14.
High-frequency field measurements of diurnal carbon isotope discrimination and internal conductance in a semi-arid species, Juniperus monosperma 总被引:1,自引:0,他引:1
CHRISTOPHER P. BICKFORD NATE G. MCDOWELL ERIK B. ERHARDT & DAVID T. HANSON 《Plant, cell & environment》2009,32(7):796-810
We present field observations of carbon isotope discrimination (Δ) and internal conductance of CO2 ( g i ) collected using tunable diode laser spectroscopy (TDL). Δ ranged from 12.0 to 27.4‰ over diurnal periods with daily means from 16.3 ± 0.2‰ during drought to 19.0 ± 0.5‰ during monsoon conditions. We observed a large range in g i , with most estimates between 0.04 and 4.0 µ mol m−2 s−1 Pa−1 . We tested the comprehensive Farquhar, O'Leary and Berry model of Δ (Δcomp ), a simplified form of Δcomp (Δsimple ) and a recently suggested amendment (Δrevised ). Sensitivity analyses demonstrated that varying g i had a substantial effect on Δcomp , resulting in mean differences between observed Δ (Δobs ) and Δcomp ranging from 0.04 to 9.6‰. First-order regressions adequately described the relationship between Δ and the ratio of substomatal to atmospheric CO2 partial pressure ( p i / p a ) on all 3 d, but second-order models better described the relationship in July and August. The three tested models each best predicted Δobs on different days. In June, Δsimple outperformed Δcomp and Δrevised , but incorporating g i and all non-photosynthetic fractionations improved model predictions in July and August. 相似文献
15.
Larry L. Tieszen Michael M. Senyimba Simeon K. Imbamba John H. Troughton 《Oecologia》1979,37(3):337-350
Summary More than 500 species of the Poaceae are found in Kenya, East Africa. Eighteen of twenty-seven tribes are exclusively (except the Paniceae and Danthonieae) of the C3 photosynthetic type. A floristic analysis of low altitude grasslands suggests that nearly all species at these low altitudes are of the C4 photosynthetic type. At high altitudes, however, nearly all grasses are of the C3 photosynthetic type. Open grassland vegetation was sampled along a transect from arid low altitude sites to the top of Mt. Kenya in an attempt to document the general distributions of the photosynthetic types.The major tribes illustrated three general patterns of distribution. The C4 tribes Chlorideae, Eragrosteae, Sporoboleae, and Aristideae were abundant at low altitudes (or low indices of available soil moisture). The Paniceae and Andropogoneae were also exclusively C4 but were more common at intermediate altitudes. The C3 tribes Aveneae, Festuceae, and Agrostideae were found only at high altitudes. In these open grasslands there were no C3 species below 2,000 m and no C4 species above 3,000 m. The variation in 13C of the live grass vegetation with altitude confirms these distributional patterns and suggests a sharp transition zone between these two photosynthetic types. The photosynthetic type accounts for broad distributions within the Poaceae but these distributions are further modified by characteristics which may be inherent in the tribal groups. Ecological and paleoecological significance of these patterns of distribution are discussed. 相似文献
16.
Photosynthetic gas exchange and the stable isotope composition of leaf water: comparison of a xylem-tapping mistletoe and its host 总被引:4,自引:2,他引:2
Photosynthetic gas exchange and the stable isotopic composition of foliage water were measured for a xylem tapping mistletoe, Phoradendron juniperinum, and its host tree, Juniperus osteosperma, growing in southern Utah. The observed isotopic composition of water extracted from foliage was compared to predictions of the Craig-Gordon model of isotopic enrichment at evaporative sites within leaves. Assimilation rates of juniper were higher and stomatal conductance was lower than the values observed for the mistletoe. This resulted in lower intercellular/ ambient CO2 values in the juniper tree relative to its mistletoe parasite. For mistletoe, the observed foliage water hydrogen and oxygen isotopic enrichment was less than that predicted by the model. In juniper, foliage water hydrogen isotopic enrichment was also lower than that predicted by the evaporative enrichment model. In contrast, the oxygen isotopic enrichment in juniper foliage water was slightly greater than that predicted for the evaporative sites within leaves. Hydrogen isotopic enrichment in mistletoe foliage shows systematic variation with stem segment, being highest near the tips of the youngest stems and decreasing toward the base of the mistletoe, where isotopic composition is close to that of stem water in the host tree. In a correlated pattern, mid-day stomatal conductance declined abruptly in mistletoe foliage of increasing age. 相似文献
17.
Patrick Z. Ellsworth Max J. Feldman Ivan Baxter Asaph B. Cousins 《The Plant journal : for cell and molecular biology》2020,102(6):1234-1248
Genetic selection for whole‐plant water use efficiency (yield per transpiration; WUEplant) in any crop‐breeding programme requires high‐throughput phenotyping of component traits of WUEplant such as intrinsic water use efficiency (WUEi; CO2 assimilation rate per stomatal conductance). Measuring WUEi by gas exchange measurements is laborious and time consuming and may not reflect an integrated WUEi over the life of the leaf. Alternatively, leaf carbon stable isotope composition (δ13Cleaf) has been suggested as a potential time‐integrated proxy for WUEi that may provide a tool to screen for WUEplant. However, a genetic link between δ13Cleaf and WUEplant in a C4 species has not been well established. Therefore, to determine if there is a genetic relationship in a C4 plant between δ13Cleaf and WUEplant under well watered and water‐limited growth conditions, a high‐throughput phenotyping facility was used to measure WUEplant in a recombinant inbred line (RIL) population created between the C4 grasses Setaria viridis and S. italica. Three quantitative trait loci (QTL) for δ13Cleaf were found and co‐localized with transpiration, biomass accumulation, and WUEplant. Additionally, WUEplant for each of the δ13Cleaf QTL allele classes was negatively correlated with δ13Cleaf, as would be predicted when WUEi influences WUEplant. These results demonstrate that δ13Cleaf is genetically linked to WUEplant, likely to be through their relationship with WUEi, and can be used as a high‐throughput proxy to screen for WUEplant in these C4 species. 相似文献
18.
Monclus R Dreyer E Delmotte FM Villar M Delay D Boudouresque E Petit JM Marron N Bréchet C Brignolas F 《The New phytologist》2005,167(1):53-62
Here we tested whether some leaf traits could be used as predictors for productivity in a range of Populus deltoides x P. nigra clones. These traits were assessed in 3-yr-old rooted cuttings from 29 clones growing in an open field trial, in a five randomized complete block design, under optimal irrigation. Variables were assigned to four groups describing productivity (above-ground biomass, total leaf area), leaf growth (total number of leaves increment rate), leaf structure (area of the largest leaf, specific leaf area, carbon and nitrogen contents), and carbon isotope discrimination in the leaves (Delta). High-yielding clones displayed larger total leaf area and individual leaf area, while no correlation could be detected between productivity and either leaf structure or Delta. By contrast, Delta was negatively correlated with number of leaves increment rate and leaf N content. Our study shows that there is a potential to improve water-use efficiency in poplar without necessarily reducing the overall productivity. 相似文献
19.
YING SUN LIANHONG GU ROBERT E. DICKINSON STEPHEN G. PALLARDY JOHN BAKER YONGHUI CAO FÁBIO MURILO DAMATTA XUEJUN DONG DAVID ELLSWORTH DAVINA VAN GOETHEM ANNA M. JENSEN BEVERLY E. LAW RODOLFO LOOS SAMUEL C. VITOR MARTINS RICHARD J. NORBY JEFFREY WARREN DAVID WESTON KLAUS WINTER 《Plant, cell & environment》2014,37(4):978-994
Worldwide measurements of nearly 130 C3 species covering all major plant functional types are analysed in conjunction with model simulations to determine the effects of mesophyll conductance (gm) on photosynthetic parameters and their relationships estimated from A/Ci curves. We find that an assumption of infinite gm results in up to 75% underestimation for maximum carboxylation rate Vcmax, 60% for maximum electron transport rate Jmax, and 40% for triose phosphate utilization rate Tu. Vcmax is most sensitive, Jmax is less sensitive, and Tu has the least sensitivity to the variation of gm. Because of this asymmetrical effect of gm, the ratios of Jmax to Vcmax, Tu to Vcmax and Tu to Jmax are all overestimated. An infinite gm assumption also limits the freedom of variation of estimated parameters and artificially constrains parameter relationships to stronger shapes. These findings suggest the importance of quantifying gm for understanding in situ photosynthetic machinery functioning. We show that a nonzero resistance to CO2 movement in chloroplasts has small effects on estimated parameters. A non‐linear function with gm as input is developed to convert the parameters estimated under an assumption of infinite gm to proper values. This function will facilitate gm representation in global carbon cycle models. 相似文献
20.
Summary Carbon 13/12 isotope ratios have been determined from leaves of a hundred C3 plant species (or ecotypes) from all major mountain ranges of the globe, avoiding drought stressed areas. A general increase in 13C content was found with increasing altitude, i.e. overall discrimination against the heavy isotope is reduced at high elevation. The steepest decline of discrimination is observed in taxa typically ranging to highest elevations (e.g. the genus Ranunculus). Mean 13C for all samples collected between 2500 and 5600 m altitude is-26.15 compared to the lowland average of-28.80 (P<0.001). Forbs from highest elevations reach-24. According to theory of 13C discrimination this indicates decreasing relative limitation of carbon uptake by carboxylation. In other words, we estimate that the ratio of internal to external partial pressure of CO2 (p
i
/p
a
)in leaves of high elevation plants is lower than in leaves of low altitude. These results confirm recent gas exchange analyses in high and low elevation plants. 相似文献