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1.
During the grain filling period we followed diurnal courses in leaf water potential (ψ1), leaf osmotic potential (ψπ), transpiration (E), leaf conductance to water vapour transfer (g) and microclimatic parameters in field-grown spring barley
(Hordeum distichum L. cv. Gunnar). The barley crop was grown on a coarse textured sandy soil at low (50 kg ha−1) or high (200 kg ha−1) levels of potassium applied as KCl. The investigation was undertaken at full irrigation or under drought. Drought was imposed
at the beginning of the grain filling period.
Leaf conductance and rate of transpiration were higher in the flag leaf than in the leaves of lower insertion. The rate of
transpiration of the awns on a dry weight basis was of similar magnitude to that of the flag leaves. On clear days the rate
of transpiration of fully watered barley plants was at a high level during most part of the day. The transpiration only decreased
at low light intensities. The rate of transpiration was high despite leaf water potentials falling to rather low values due
to high evaporative demands. In water stressed plants transpiration decreased and midday depression of transpiration occurred.
Normally, daily accumulated transpirational water loss was lower in high K leaves than in low K leaves and generally the bulk
water relations of the leaves were more favourable in high K plants than in low K plants.
The factorial dependency of the flag leaf conductances on leaf water potential, light intensity, leaf temperature, and leaf-to-air
water vapour concentration difference (ΔW) was analysed from a set of field data. From these data, similar sets of microclimatic
conditions were classified, and dependencies of leaf conductance on the various environmental parameters were ascertained.
The resulting mathematical functions were combined in an empirical simulation model. The results of the model were tested
against other sets of measured data. Deviations between measured and predicted leaf conductance occurred at low light intensities.
In the flag leaf, water potentials below-1.6 MPa reduced the stomatal apertures and determined the upper limit of leaf conductance.
In leaves of lower insertion level conductances were reduced already at higher leaf water potentials. Leaf conductance was
increased hyperbolically as photosynthetic active radiation (PAR) increased from darkness to full light. Leaf conductance
as a function of leaf temperature followed an optimum curve which in the model was replaced by two linear regression lines
intersecting at the optimum temperature of 23.4°C. Increasing leaf-to-air water vapour concentration difference caused a linear
decrease in leaf conductance. Leaf conductances became slightly more reduced by lowered water potentials in the low K plants.
Stomatal closure in response to a temperature change away from the optimum was more sensitive in high K plants, and also the
decrease in leaf conductance under the influence of lowered ambient humidity proceeded with a higher sensitivity in high K
plants. Thus, under conditions which favoured high conductances increase of evaporative demand caused an about 10% larger
decrease in leaf conductance in the high K plants than in the low K plants.
Stomatal sizes and density in the flag leaves differed between low and high K plants. In plants with partially open stomata,
leaf conductance, calculated from stomatal pore dimensions, was up to 10% lower in the high K plants than in the low K plants.
A similar reduction in leaf conductance in high K plants was measured porometrically. It was concluded that the beneficial
effect of K supply on water use efficiency reported in former studies primarily resulted from altered stomatal sizes and densities. 相似文献
2.
Attempts to improve water use efficiency in regions with Mediterranean climates generally focus on increasing plant transpiration
relative to evaporation from the soil and increasing transpiration efficiency. Our aim was to determine if transpiration efficiency
differs among key species occurring in annual pastures in southern Australia. Two glasshouse experiments were conducted with
three key pasture species, subterranean clover (Trifolium subterraneum L.), capeweed [Arctotheca calendula (L.) Levyns] and annual ryegrass (Lolium rigidum Gaudin), and wheat (Triticum aestivum L.). Transpiration efficiency was assessed at the levels of␣whole-plant biomass and water use (W), leaf gas exchange measurements of the ratio of CO2 assimilation to leaf conductance to water vapour (A/g), and carbon isotope discrimination (Δ) in leaf tissue. In addition, Δ was measured on shoots of the three pasture species
growing together in the field. In the glasshouse studies, annual ryegrass had a consistently higher transpiration efficiency
than subterranean clover or capeweed by all methods of measurement. Subterranean clover and capeweed had similar transpiration
efficiencies by all three methods of measurement. Wheat had W values similar to ryegrass but A/g and Δ values similar to subterranean clover or capeweed. The high W of annual ryegrass seems to be related to a conservative leaf gas exchange behaviour, with lower assimilation and conductance
but higher A/g than for the other species. In contrast to the glasshouse results, the three pasture species had similar Δ values when growing
together in mixed-species swards in the field. Reasons for these differing responses between glasshouse and field-grown plants
are discussed in terms of the implications for improving the transpiration efficiency of mixed-species annual pasture communities
in the field.
Received: 6 March 1997 / Accepted: 23 December 1997 相似文献
3.
Among grain legumes, faba bean is becoming increasingly popular in European agriculture due to recent economic and environmental
interests. Faba bean can be a highly productive crop, but it is sensitive to drought stress and yields can vary considerably
from season to season. Understanding the physiological basis of drought tolerance would indicate traits that can be used as
indirect selection criteria for the development of cultivars adapted to drought conditions. To assess genotypic variation
in physiological traits associated with drought tolerance in faba bean and to determine relationships among these attributes,
two pot experiments were established in a growth chamber using genetic materials that had previously been screened for drought
response in the field. Nine inbred lines of diverse genetic backgrounds were tested under adequate water supply and limited
water conditions. The genotypes showed substantial variation in shoot dry matter, water use, stomatal conductance, leaf temperature,
transpiration efficiency, carbon isotope discrimination (Δ13C), relative water content (RWC) and osmotic potential, determined at pre-flowering vegetative stage. Moisture deficits decreased
water usage and consequently shoot dry matter production. RWC, osmotic potential, stomatal conductance and Δ13C were lower, whereas leaf temperature and transpiration efficiency were higher in stressed plants, probably due to restricted
transpirational cooling induced by stomatal closure. Furthermore, differences in stomatal conductance, leaf temperature, Δ13C and transpiration efficiency characterized genotypes that were physiologically more adapted to water deficit conditions.
Correlation analysis also showed relatively strong relationships among these variables under well watered conditions. The
drought tolerant genotypes, ILB-938/2 and Melodie showed lower stomatal conductance associated with warmer leaves, whereas
higher stomatal conductance and cooler leaves were observed in sensitive lines (332/2/91/015/1 and Aurora/1). The lower value
of Δ13C coupled with higher transpiration efficiency in ILB-938/2, relative to sensitive lines (Aurora/1 and Condor/3), is indeed
a desirable characteristic for water-limited environments. Finally, the results showed that stomatal conductance, leaf temperature
and Δ13C are promising physiological indicators for drought tolerance in faba bean. These variables could be measured in pot-grown
plants at adequate water supply and may serve as indirect selection criteria to pre-screen genotypes. 相似文献
4.
Water relations dynamics during simulated sunflecks at high (36°C) and medium (27°C) temperatures and high and low vapour
pressure deficits beween leaf and air (VPD) were studied on shade-grown Piper auritum H.B. & K. plants, a pioneer tree, common in gaps and clearings of tropical rain forests. The leaves of P. auritum wilt rapidly when exposed to high light. Exposure to high VPD and high light caused substantial and rapid dehydration of
leaves. Dehydration could be prevented under high humidity irrespective of temperature. Water stored in leaf cells served
as initial source for transpiration upon high light exposure. This effect increased with increasing VPD and temperature. The
pronounced decrease in leaf water content over time in high light caused a rapid decrease in leaf water potential (Ψl) and a concomitant increase in water potential gradient (ΔΨ/Δx) between trunk and leaf, yet the high leaf elasticity (small bulk elastic modulus, ε) allowed turgor maintenance under most
conditions. Under high VPD and high temperature, stomata remained open and ΔΨ/Δx frequently exceeded 0.95 MPa · m−1, the cavitation-inducing threshold (ΔΨ/Δx
cav) causing high rates of acoustic emissions from stems and leaf petioles and leading to concomitant losses in hydraulic conductance
per leaf area (k
l). At medium temperature (high VPD), stomatal closure contained xylem embolism by keeping ΔΨ/Δx at or below this threshold. We argue that wilting substantially contributes to creating a sufficient driving force for water
uptake from the soil, and reducing the VPD (through a decrease in radiation load and thus leaf temperature) to avoid excessive
dehydration.
Received: 3 March 1996 / Accepted: 10 November 1996 相似文献
5.
Jana PospíšilovÁ 《Biologia Plantarum》1973,15(4):290-293
The relationship between the water potential (Ψw) and the water saturation deficit (Δ W sat) in kale and maize leaf tissue was measured during dehydration and resaturation either of leavesin situ or of cut leaves. The curves relating Ψw toΔW sat were similar in all variants, but at the same values ofΔ W sat corresponding values of Ψw were always lower in leavesin situ than in cut leaves and during dehydration than during resaturation. 相似文献
6.
Jana Pospíšilová 《Biologia Plantarum》1974,16(2):140-143
The water potential (Ψ w ) and the water saturation deficit (δW sat) in leaves of different insertion levels of potted kale plants were simultaneously measured. In non-wilting plantsδW sat gradually decreased andΨ w slightly increased from the upper to the lower leaves. During the wilting of the plants induced by decreasing of soil moistureΨw practically decreased paralelly in all the leaves but the same decrease ofΨ w was connected with the lowest increase ofδW sat in upper leaves and the highest increase ofδW sat in lower leaves. Not only the values ofΨ w andδW sat but also their relationship varied considerably with the leaf insertion levels. 相似文献
7.
J. Čatský D. K. Velichkov Jana Pospísilová Jarmila Solárová Ingrid Tichá 《Biologia Plantarum》1987,29(5):355-364
The carbon balances of whole, 21-d old French bean plants (Phaseolus vulgaris L.) grown in standard nutrient solution (1K) and its modifications without (OK) or surplus (2K) potassium were calculated
from the daily photosynthetic carbon inputs of individual leaves, and the daily respiratory carbon losses by individual leaves,
stalks and petioles, and roots. Under the three K concentrations, maximum net photosynthetic rates (Pn) were found in the 2nd or in the 3rd trifoliate leaves, maximum respiratory rates (Rd) in the youngest, 4th trifoliate leaves; the Pn/Rd ratio decreased with leaf age. In all leaves of 2K plants, leaf dry masses and thicknesses, Pn, Pn/Pd ratios, and stomatal and intracellular conductances were lower than in OK and IK plants. Daily whole-plant net carbon gain
was highest in IK plants, whereas in OK and 2K plants it was 98.0 and 81.3 % of IK, respectively. Similar values were found
in the parameters of growth analysis, namely in net assimilation rates and relative growth rates.
No differences were found in water potential (Ψ
w
) or water saturation deficit (Wsat) in the OK, 1K and 2K plants sufficiently supplied with water or during wilting and resaturation. The decrease in Ψw to −0.97 MPa was associated with a 19.9 %, 31.4 % and 23.4 % decrease in Pn of OK, 1K and 2K plants, respectively, but no effect on Rd was found. In the three variants, the short-time effect of mild water stress was fully reversible. 相似文献
8.
The development of temporary water stress during the day-light hours, characterized by a decrease of the values of the water potential (?w) and increase of the values of water saturation deficit (ΔW sat) was found not only in the leaves of intact kale plants but also in cut leaves with their petioles immersed in water. These results indicate that the leaf resistance to water transport could not be supposed as negligible. The same decrease of ? w was accompanied with the higher increase of ΔW sat in cut leaves than in leavesin situ. 相似文献
9.
Main Conclusion
Modifications in leaf anatomy of tobacco plants induced greater leaf water transport capacity, meeting greater transpirational demands and acclimating to warmer temperatures with a higher vapor pressure deficit. Temperature is one of the most important environmental factors affecting photosynthesis and growth of plants. However, it is not clear how it may alter leaf hydraulic architecture. We grew plants of tobacco (Nicotiana tabacum) ‘k326’ in separate glasshouse rooms set to different day/night temperature conditions: low (LT 24/18 °C), medium (MT 28/22 °C), or high (HT 32/26 °C). After 40 days of such treatment, their leaf anatomies, leaf hydraulics, photosynthetic rates, and instantaneous water-use efficiency (WUEi) were measured. Compared with those under LT, plants exposed to HT or MT conditions had significantly higher values for minor vein density (MVD), stomatal density (SD), leaf area, leaf hydraulic conductance (K leaf), and light-saturated photosynthetic rate (A sat), but lower values for leaf water potential (ψ l) and WUEi. However, those parameters did not differ significantly between HT and MT conditions. Correlation analyses demonstrated that SD and K leaf increased in parallel with MVD. Moreover, greater SD and K leaf were partially associated with accelerated stomatal conductance. And then stomatal conductance was positively correlated with A sat. Therefore, under well-watered, fertilized conditions, when relative humidity was optimal, changes in leaf anatomy seemed to facilitate the hydraulic acclimation to higher temperatures, meeting greater transpirational demands and contributing to the maintenance of great photosynthetic rates. Because transpiration rate increased more with temperature than photosynthetic rate, WUEi reduced under warmer temperatures. Our results indicate that the modifications of leaf hydraulic architecture are important anatomical and physiological strategies for tobacco plants acclimating to warmer temperatures under a higher vapor pressure deficit. 相似文献10.
TERUO OGAWA 《Physiologia plantarum》1975,35(2):91-95
Photosynthesis and transpiration of excised leaves of Taraxacum officinale L. and a few other species of plants were measured, using an open gas analysis system. The rates of CO2 uptake and transpiration increased in two steps upon illumination of stomata-bearing epidermis of these leaves at a light intensity of 50 mW × cm−2. Abscisic acid inhibited only the second step of gas exchange. Illumination of the astomatous epidermis of hypostomatous leaves caused only the first step of gas exchange. These data indicate that the first and second steps arise from cuticular and stomatal gas exchange, respectively. The rate of the cuticular photosynthesis in a Taraxacum leaf reached saturation at a light intensity of 5 mW × cm−2, and the rates of the stomatal photosynthesis and transpiration reached saturation at a higher intensity of 35 mW × cm−2. The cuticular photosynthesis of a Taraxacum leaf was 18% of the stomatal photosynthesis at 50 mW × cm−2 and 270% at 5 mW × cm−2. The other species of leaves showed the same trend. The importance of cuticular CO2 uptake in leaf photosynthesis, especially under low light intensity was stressed from these data. 相似文献
11.
Initial results of the airborne LIDAR measurement of photochemical quantum yield, ΦPo, and functional absorption cross-section, σPS II, of Photosystem II (PS II) are reported. NASA's AOL3 LIDAR was modified to implement short-pulse pump-and-probe (SP-P&P)
LIDAR measurement protocol. The prototype system is capable of measuring a pump-induced increase in probe-stimulated chlorophyll
fluorescence, ΔF/Fsat, along with the acquisition of `conventional' LIDAR-fluorosensor products from an operational altitude of 150 m. The use
of a PS II sub-saturating probe pulse increases the response signal but also results in excessive energy quenching (EEQ) affecting
the ΔF/Fsat magnitude. The airborne data indicated up to a 3-fold EEQ-caused decline in ΔF/Fsat, and 2-fold variability in the EEQ rate constant over a spatial scale a few hundred kilometers. Therefore, continuous monitoring
of EEQ parameters must be incorporated in the operational SP-P&P protocol to provide data correction for the EEQ effect. Simultaneous
airborne LIDAR measurements of ΦPo and σPS II with EEQ correction were shown to be feasible and optimal laser excitation parameters were determined. Strong daytime ΔF/Fsat decline under ambient light was found in the near-surface water layer over large aquatic areas. An example of SP-P&P LIDAR
measurement of phytoplankton photochemical and fluorescent characteristics in the Chesapeake Bay mouth is presented. Prospects
for future SP-P&P development and related problems are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
The Effect of VA Mycorrhizal Infection and Phosphorus Status on Sunflower Hydraulic and Stomatal Properties 总被引:6,自引:0,他引:6
Koide, R. 1985. The effect of VA mycorrhizal infection and phosphorusstatus on sunflower hydraulic and stomatal properties.J. exp. Bot. 36: 10871098. Mycorrhizal (M) and non-mycorrhizal (NM) sunflower plants weregrown in a soil of low phosphorus availability (with and withoutphosphorus amendment) and in a soil of moderate phosphorus availability(without phosphorus amendment). Using the Ohm's law analogyand measured leaf water potentials, stem water potentials, andtranspiration rates, hydraulic resistances were calculated forthe whole plant, leaf, and below leaf components. Mycorrhizalinfection (as high as 89%) was shown to have no effect on theintrinsic hydraulic properties of the soil/plant system overa wide range of transpiration rates in either soil when M andNM plants of equivalent root length were compared. When grownin the soil of moderate phosphorus availability, calculatedhydraulic resistances under given environmental conditions werethe same for M and NM plants, as were stomatal resistances andtranspiration rates. When grown in the soil of low phosphorusavailability, calculated values of hydraulic resistance werelower for M plants than for NM plants under given sets of environmentalconditions. These differences in calculated hydraulic resistancewere not due to a difference in the intrinsic hydraulic propertiesof M and NM plants. The differences were evident because stomatalresistances were lower and transpiration rates higher for Mplants and because hydraulic resistance varied inversely withtranspiration rate. When plants of significantly greater rootlength were compared to plants of lesser root length, the calculatedhydraulic resistances under given environmental conditions weremuch lower for the plants of greater root length. This differencewas largely due to a difference in the intrinsic hydraulic propertiesbetween large and small plants, and not because of differencesin transpiration rate. The elevated transpiration rates exhibitedby M plants were attributed to an enhanced phosphorus status.Short term phosphorus amendments made to phosphorus-deficientNM plants improved transpiration; transpiration rates were similarfor M and NM plants before NM plants became phosphorus-deficient,and phosphorus-amended M and NM plants had similar transpirationrates. The data are discussed in relation to other reports ofmycorrhizal influence on hydraulic and stomatal resistances.Possible mechanisms for the influence of infection on stomatalresistance are also briefly discussed. Key words: Hydraulic resistance, stomatal resistance, mycorrhizas 相似文献
13.
Photosynthetic and stomatal responses of two tropical and two temperate trees to atmospheric humidity 总被引:4,自引:0,他引:4
The effects of leaf to air vapour pressure differences (ΔW) on net photosynthetic rate (PN) and stomatal conductance (gs) were examined in the leaves of two tropical rain forest trees, Eugenia grandis and Pongamia pinnata, and two temperate evergreen
trees, Viburnum awabuki and Daphniphyllum macropodum. A single leaf was set inside a small chamber and ΔW was varied from
7 to 24 mmol mol-1 at 25 and 500 μmol m-2 s-1 of photon flux density. PN and gs of the two tropical rain forest trees decreased with increasing ΔW, while the two temperate evergreen trees were not highly
responsive to ΔW. P. pinnata was more sensitive to ΔW in its stomatal response, and had a higher stomatal density and higher
stomatal index than did the two temperate trees and another tropical tree. Significant reductions i n gs and intercellular CO2 concentrations in the two tropical trees at high ΔW suggest that the decline of PN was due to the decrease in gs. The responses of PN and gs indicated that the tropical trees were more sensitive to ΔW than were the temperate ones.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
14.
Photosynthetic gas exchange, vegetative growth, water relations and fluorescence parameters as well as leaf anatomical characteristics
were investigated on young plants of two Olea europaea L. cultivars (Chemlali and Zalmati), submitted to contrasting water availability regimes. Two-year-old olive trees, grown
in pots in greenhouse, were not watered for 2 months. Relative growth rate (RGR), leaf water potential (ΨLW) and the leaf relative water content (LWC) of the two cultivars decreased with increasing water stress. Zalmati showed higher
values of RGR and LWC and lower decreased values of ΨLW than Chemlali, in response to water deficit, particularly during severe drought stress. Water stress also caused a marked
decline on photosynthetic capacity and chlorophyll fluorescence. The net photosynthetic rate, stomatal conductance, transpiration
rate, the maximal photochemical efficiency of PSII (F
v/F
m) and the intrinsic efficiency of open PSII reaction centres (F′
v/F′
m) decreased as drought stress developed. In addition, drought conditions, reduced leaf chlorophyll and carotenoids contents
especially at severe water stress. However, Zalmati plants were the less affected when compared with Chemlali. In both cultivars,
stomatal control was the major factor affecting photosynthesis under moderate drought stress. At severe drought-stress levels,
the non-stomatal component of photosynthesis is inhibited and inactivation of the photosystem II occurs. Leaf anatomical parameters
show that drought stress resulted in an increase of the upper epidermis and palisade mesophyll thickness as well as an increase
of the stomata and trichomes density. These changes were more characteristic in cv. ‘Zalmati’. Zalmati leaves also revealed
lower specific leaf area and had higher density of foliar tissue. From the behaviour of Zalmati plants, with a smaller reduction
in relative growth rate, net assimilation rate and chlorophyll fluorescence parameters, and with a thicker palisade parenchyma,
and a higher stomatal and trichome density, we consider this cultivar more drought-tolerant than cv. Chemlali and therefore,
very promising for cultivation in arid areas. 相似文献
15.
The photosynthetic characteristics of differently shaped leaves in Populus euphratica Olivier 总被引:4,自引:0,他引:4
There is a distinct leaf shape polymorphism within a single plant of P. euphratica Olivier. The anatomical structure, carbon isotope discrimination (Δ13C), and stomatal and photosynthetic behaviour were investigated in broad-ovate (BOL) and lanceolate (LL) leaves, located at
the top and bottom in crown, respectively, of a mature Euphrates poplar growing in its native habitat. Both types of leaves
had a non-Kranz anatomy and low Δ13C values. However, Δ13C of a LL was in average 3.2‰ larger than that of a BOL. In comparison with the LL, the BOL had a smaller stomatal conductance,
causing subsequent decreases in transpiration rate and ratio of CO2 concentrations in intercellular spaces to air. Carbon assimilation rate and water use efficiency were higher in the BOLs
than in the LLs. The BOL exhibited C4-like enzymological features, the activity of glycollate oxidase, and the ratio of activities of ribulose-1,5-bisphosphate
carboxylase (RuBPC) to phosphoenolpyruvate carboxylase (PEPC) was lower in BOL than in LL throughout the whole growing season.
The lowered ratio of RuBPC/PEPC in BOL was mainly associated with a marked decline in the activity of RuBPC, and only a slight
increase in the activity of PEPC. These differences might contribute to microclimate adaptation in both types of leaves.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Transpiration and photosynthesis of current-year stems and adult leaves of different deciduous tree species were investigated
to estimate their probable influence on carbon balance. Peridermal transpiration of young stems was found to be rather small
as compared to the transpiration of leaves (stem/leaf like 1/5–1/20). A characteristic that was mainly attributable to the
lower peridermal conductance to water and CO2, which made up only 8–28% of stomatal conductance. Water vapour conductance was significantly lower in stems, but also non-responsive
to PAR, which led to a comparatively higher water use efficiency (WUE, ratio assimilation/transpiration). Thus, although corticular
photosynthesis reached only 11–37% of leaf photosynthesis, it may be a means of improving the carbon balance of stems under
limited water availability. The influence of drought stress on primary photosynthetic reactions was also studied. Under simulated
drought conditions the drying time needed to provoke a 50% reduction (t
50) in dark- and light-adapted PSII efficiency (Fv/Fm, ΔF/Fm′) was up to ten times higher in stems than in leaves. Nevertheless,
up to a relative water deficit (RWD) of around 40–50% dark-adapted PSII efficiency of leaves and stems was rather insensitive
to dehydration, showing that the efficiency of open PS II reaction centres is not impaired. Thus, it may be concluded that
in stems as well as in leaves the primary site of drought damage is at the level of dark enzyme reactions and not within PSII.
However, enduring severe drought caused photoinhibitory damage to the photosynthetic apparatus of leaves and stems; thereby
RWD50 values (= RWD needed to provoke a 50% reduction in Fv/Fm ad ΔF/Fm′) were comparably lower in stems as compared to leaves,
indicating a possibly higher drought sensitivity of the cortex chlorenchyma. 相似文献
17.
Leaf carbon isotope discrimination (Δ13C) varies with the balance between net photosynthesis (A) and stomatal conductance (g
s
). Inferences that can be made with Δ13C are limited, as changes could reflect variation in A and/or g
s
. Investigators have suggested that leaf δ18O enrichment above source water (Δ18O) may enable differentiation between sources of variation in Δ13C, as leaf Δ18O varies with transpiration rate (E), which is closely correlated with g
s
when leaves experience similar leaf to air vapor pressure differences. We examined leaf gas exchange of Salix arctica at eight sites with similar air temperatures and relative humidities but divergent soil temperatures and soil water contents
near Pituffik, Greenland (76°N, 38°W). We found negative correlations at the site level between g
s
and Δ18O in bulk leaf tissue (r
2 = 0.62, slope = −17.9‰/mol H2O m−2 s−1, P = 0.02) and leaf α-cellulose (r
2 = 0.83, slope = −11.5‰ mol H2O m−2 s−1, P < 0.01), consistent with the notion that leaf water enrichment declines with increasing E. We also found negative correlations at the site-level between intrinsic water-use efficiency (iWUE) and Δ13C in bulk leaf tissue (r
2 = 0.65, slope = −0.08‰/μmol CO2 /mol H2O, P = 0.02) and leaf α-cellulose (r
2 = 0.50, slope = −0.05 ‰/[μmol CO2 /mol H2O], P = 0.05). When increasing Δ13C was driven by increasing g
s
alone, we found negative slopes between Δ13C and Δ18O for bulk leaf tissue (−0.664) and leaf α-cellulose (−1.135). When both g
s
and A
max increased, we found steeper negative slopes between Δ13C and Δ18O for bulk leaf tissue (−2.307) and leaf α-cellulose (−1.296). Our results suggest that the dual isotope approach is capable
of revealing the qualitative contributions of g
s
and A
max to Δ13C at the site level. In our study, bulk leaf tissue was a better medium than leaf α-cellulose for application of the dual
isotope approach. 相似文献
18.
Kenji Kanemoto Yumiko Yamashita Tomoko Ozawa Naomi Imanishi Nguyen Tran Nguyen Ryuichi Suwa Pravat Kumar Mohapatra Syunsuke Kanai Reda E. Moghaieb Junki Ito Hany El-Shemy Kounosuke Fujita 《Plant science》2009,177(5):398-403
Physiological processes that modulate photosynthetic acclimation to rising atmospheric CO2 concentration are subjects of intense discussion recently. Apparently, the down-regulation of photosynthesis under elevated CO2 is not understood clearly. In the present study, the response of soybean (Glycine max L.) to CO2 enrichment was examined in terms of nitrogen partitioning and water relation. The plants grown under potted conditions without combined N application were exposed to either ambient air (38 Pa CO2) or CO2 enrichment (100 Pa CO2) for short (6 days) and long (27 days). Plant biomass, apparent photosynthetic rate, transpiration rate and 15N uptake and partitioning were measured consecutively after elevated CO2 treatment. Long-term exposure reduced photosynthetic rate, stomatal conductance and transpiration rate. In contrast, short-term exposure increased biomass production of soybean due to increase in dry weight of leaves. Leaf N concentration tended to decrease with CO2 enrichment, however such difference was not true for stem and roots.A close correlation was observed between transpiration rate and 15N partitioned into leaves, suggesting that transpiration plays an important role on nitrogen partitioning to leaves. In conclusion existence of a feed back mechanism for photosynthetic acclimation has been proposed. Down-regulation of photosynthetic activity under CO2 enrichment is caused by decreasing leaf N concentration, and reduced rate of transpiration owing to decreased stomatal conductance is partially responsible for poor N translocation. 相似文献
19.
Potassium deficient (−K) and potassium sufficient (+K) plants were exposed to four days of water stress. Well watered −K and
+K plants had comparable rates of transpiration. But +K plants had a larger leaf area and depleted the soil moisture to a
greater extent on day 1 of stress. For days 2 and 3 their transpiration rate, leaf water potential and relative water content
fell below those of −K plants. Well watered −K plants had a significantly lower rate of photosynthesis than +K plants. Photosynthesis
of −K plants was more sensitive to reduction in plant water potential than that of +K plants. Reduction of photosythesis in
−K leaves was due to impairment of photosynthetic capacity and not to stomatal closure. Growth was significantly reduced in
−K plants. 相似文献
20.
Nonstomatal inhibition of photosynthesis at low water potentials in intact leaves of species from a variety of habitats 总被引:6,自引:2,他引:4
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Bunce JA 《Plant physiology》1977,59(3):348-350
Mesophyll resistance to CO2 uptake was calculated from gas exchange data on intact leaves of 12 species of woody plants. Plants studied were native to habitats ranging from streamsides to deserts. Gas exchange measurements were made at light saturation and constant temperature to eliminate possible effects of light and temperature on estimates of mesophyll resistance. Cuticular transpiration was measured and used in calculation of stomatal resistances from whole leaf transpiration rates. In all species examined, an increase in mesophyll resistance was observed as leaves dried. The increase in mesophyll resistance in all cases occurred at the same water potential as the initial decline in net photosynthesis, and was accompanied by an increase in stomatal resistance. 相似文献