共查询到20条相似文献,搜索用时 15 毫秒
1.
Of the four tested sweet potato cultivars having different features in growth and yield, cv. Koganesengan (KOG) was sustainable
in photosynthetic activity through young to aged leaves under drought. One of the causes for this phenomenon may be stomatal
conductance (g
s) of this cultivar that was relatively high in both aged and drought-imposed leaves. In these leaves the non-photochemical
quenching (NPQ) was low and the quantum yield of photosystem 2 (Φe) was high, compared to those of the other cultivars. This helps to prevent excessive accumulation of chemical energy in leaves
and a decrease in photoinhibition damage to the photosynthetic function, by which KOG sustains a relatively high photosynthetic
activity under the drought and alleviates functional deterioration caused by leaf age.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
The responses to irradiance of photosynthetic CO2 assimilation and photosystem 2 (PS2) electron transport were simultaneously studied by gas exchange and chlorophyll (Chl) fluorescence measurement in two-year-old apple tree leaves (Malus pumila Mill. cv. Tengmu No.1/Malus hupehensis Rehd). Net photosynthetic rate (P
N) was saturated at photosynthetic photon flux density (PPFD) 600-1 100 (mol m-2 s-1, while the PS2 non-cyclic electron transport (P-rate) showed a maximum at PPFD 800 mol m-2 s-1. With PPFD increasing, either leaf potential photosynthetic CO2 assimilation activity (Fd/Fs) and PS2 maximal photochemical activity (Fv/Fm) decreased or the ratio of the inactive PS2 reaction centres (RC) [(Fi – Fo)/(Fm – Fo)] and the slow relaxing non-photochemical Chl fluorescence quenching (qs) increased from PPFD 1 200 mol m-2 s-1, but cyclic electron transport around photosystem 1 (RFp), irradiance induced PS2 RC closure [(Fs – Fo)/Fm – Fo)], and the fast and medium relaxing non-photochemical Chl fluorescence quenching (qf and qm) increased remarkably from PPFD 900 (mol m-2 s-1. Hence leaf photosynthesis of young apple leaves saturated at PPFD 800 mol m-2 s-1 and photoinhibition occurred above PPFD 900 mol m-2 s-1. During the photoinhibition at different irradiances, young apple tree leaves could dissipate excess photons mainly by energy quenching and state transition mechanisms at PPFD 900-1 100 mol m-2 s-1, but photosynthetic apparatus damage was unavoidable from PPFD 1 200 mol m-2 s-1. We propose that Chl fluorescence parameter P-rate is superior to the gas exchange parameter P
N and the Chl fluorescence parameter Fv/Fm as a definition of saturation irradiance and photoinhibition of plant leaves. 相似文献
3.
Šetlíková E. Sofrová D. Prášil O. Budáč P. Koblížek M. Šetlík I. 《Photosynthetica》1999,37(2):183-200
The efficiency in selective extraction of photosystem (PS) 2 oxygen evolving complexes was compared among seven detergents.
These were applied to thylakoid membranes of the thermophilic cyanobacterium Synechococcus elongatus. Used were five non-ionic detergents with one ionic and one zwitterionic for comparison. To compare the suitability and efficiency
of the detergents the following properties of the extracts were examined: maximum rate of oxygen evolution with various electron
acceptors, the relative variable fluorescence (FV/FM), the contamination of the extract with photosystem (PS) 1, and the status of the electron acceptor side of PS2 reaction
centre. None of the detergents yielded a highly selective extraction of the PS2 complexes (negligible contamination with PS1)
which would simultaneously display a high photochemical activity and high structural intactness. Heptylthioglucoside and dodecylmaltoside
yielded the nearest approximation to the optimum result. Kinetic fluorometry was applied here for the first time to characterize
the functional and structural properties of PS2 particles from cyanobacteria.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Wheat (Triticum aestivum L. cv. Sonalika) seedlings were grown in Hoagland solution. Primary leaves were harvested at 8, 12, and 15 d and cut into five equal segments. Contents of photosynthetic pigments and proteins, and photosystem 2 (PS2) activity increased from base to apex of these leaves. Chlorophyll (Chl) content was maximum at 12 d in all the leaf segments, but PS2 activity showed a gradual decline from 8 to 15 d in all leaf segments. In sharp contrast, the CO2 fixation ability of chloroplasts increased from 8 to 15 d. CO2 fixation ability of chloroplasts started to decline from base to apex of 15-d-old seedlings, where the content of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (RuBPCO-LSU) increased acropetally. RuBPCO-LSU content was maximum in all the leaf segments in 12-d-old seedlings. This shows a distinctive pattern of PS2, Chl, CO2 fixation ability of chloroplasts, and RuBPCO-LSU content along the axis of leaf lamina during development and senescence. RuBPCO-LSU (54 kDa) degraded to fragments of 45, 42, 37, 19, and 16 kDa products which accumulated along the leaf axis during ageing of chloroplasts. Thus the CO2 fixation ability of chloroplasts declines earlier than PS2 activity and photosynthetic pigment contents along the leaf lamina. 相似文献
5.
A C3 monocot, Hordeum vulgare and C3 dicot, Vicia faba, were studied to evaluate the mechanism of inhibition of photosynthesis due to water stress. The net rate of CO2 fixation (A) and transpiration (E) were measured by gas exchange, while the true rate of O2 evolution (J
O2) was calculated from chlorophyll fluorescence analysis through the stress cycle (10 to 11 days). With the development of water stress, the decrease in A was more pronounced than the decrease in J
O2 resulting in an increased ratio of Photosystem II activity per CO2 fixed which is indicative of an increase in photorespiration due to a decrease in supply of CO2 to Rubisco. Analyses of changes in the J
O2
A ratios versus that of CO2 limited photosynthesis in well watered plants, and RuBP pool/RuBP binding sites on Rubisco and RuBP activity, indicate a decreased supply of CO2 to Rubisco under both mild and severe stress is primarily responsible for the decrease in CO2 fixation. In the early stages of stress, the decrease in C
i (intercellular CO2) due to stomatal closure can account for the decrease in photosynthesis. Under more severe stress, CO2 supply to Rubisco, calculated from analysis of electron flow and CO2 exchange, continued to decrease. However, C
i, calculated from analysis of transpiration and CO2 exchange, either remained constant or increased which may be due to either a decrease in mesophyll conductance or an overestimation of C
i by this method due to patchiness in conductance of CO2 to the intercellular space. When plants were rewatered after photosynthesis had dropped to 10–30% of the original rate, both species showed near full recovery within two to four days.Abbreviations
A-
net CO2 assimilation rate
-
A
*-
net CO2 assimilation rate plus dark respiration
- ATP-
adenosine triphosphate
- CABP-
carboxyarabinitol 1,5-bisphosphate
-
C
a-
ambient CO2 concentration
-
C
c-
CO2 concentration in the chloroplast
-
C
i-
intercellular CO2 concentration
-
E-
transpiration rate
-
g
m-
mesophyll conductance
-
g
s-
stomatal conductance
-
J
O2
true rate of O2 evolution
- LSD-
least significant difference
- PPFD-
photosynthetic photon flux density
- PS II-
Photosystem II
-
R
n-
dark respiration rate
- Rubisco-
ribulose 1,5-bisphosphate carboxylase/oxygenase
- RuBP-
ribulose 1,5-bisphosphate
-
RWC-
relative water content
- c-
rate of carboxylation
- o-
rate of oxygenation
- PSII-
quantum yield of Photosystem II
- -
CO2 compensation point in the absence of R
n
- -
water potential 相似文献
6.
Photosynthetic Pathway Types of Forage Species Along Grazing Gradient from the Songnen Grassland,Northeastern China 总被引:3,自引:0,他引:3
Photosynthetic pathway types (C3 and C4 species) and their dynamics along grazing gradient were determined for 42 plant species in 30 genera and 13 families from the Songnen grassland, Northeastern China. Of the total, 10 species in 9 genera and 4 families had C4 photosynthesis; 32 species in 21 genera and 12 families had C3 photosynthesis. The proportion of C4 species in total plants and C4/C3 increased with grazing intensity, and peaked in overgrazed plot. Most of the increased C4 species (6 of 10) along the grazed gradient were annual grasses and halophytes. This indicated that the C4 species had greater capacity to tolerate environmental stresses (e.g. drought and saline) caused by animal grazing in the Songnen grassland, Northeastern China. 相似文献
7.
Winter wheat plants were grown in open top chambers either at 365 µmol mol–1 (AC) or at 700 µmol mol–1 (EC) air CO2 concentrations. The photosynthetic response of flag leaves at the beginning of flowering and on four vertical leaf levels at the beginning of grain filling were measured. Net photosynthetic rates (P
N) were higher at both developmental phases in plants grown at EC coupled with larger leaf area and photosynthetic pigment contents. The widely accepted Farquhar net photosynthesis model was parameterised and tested using several observed data. After parameterisation the test results corresponded satisfactorily with observed values under several environmental conditions. 相似文献
8.
The light dependence of quantum yields of Photosystem II (II) and of CO2 fixation were determined in C3 and C4 plants under atmospheric conditions where photorespiration was minimal. Calculations were made of the apparent quantum yield for CO2 fixation by dividing the measured rate of photosynthesis by the absorbed light [A/I=CO2 and of the true quantum yield by dividing the estimated true rate of photosynthesis by absorbed light [(A+Rl)/Ia=CO2·], where RL is the rate of respiration in the light. The dependence of the II/CO2 and II/CO2
* ratios on light intensity was then evaluated. In both C3 and C4 plants there was little change in the ratio of II/CO2 at light intensities equivalent to 10–100% of full sunlight, whereas there was a dramatic increase in the ratio at lower light intensities. Changes in the ratio of II/CO2 can occur because respiratory losses are not accounted for, due to changes in the partitioning of energy between photosystems or changes in the relationship between PS II activity and CO2 fixation. The apparent decrease in efficiency of utilization of energy derived from PS II for CO2 fixation under low light intensity may be due to respiratory loss of CO2. Using dark respiration as an estimate of RL, the calculated II/CO2
* ratio was nearly constant from full sunlight down to approx 5% of full sunlight, which suggests a strong linkage between the true rate of CO2 fixation and PS II activity under varying light intensity. Measurements of photosynthesis rates and II were made by illuminating upper versus lower leaf surfaces of representative C3 and C4 monocots and dicots. With the monocots, the rate of photosynthesis and the ratio of II/CO2 exhibited a very similar patterns with leaves illuminated from the adaxial versus the abaxial surface, which may be due to uniformity in anatomy and lack of differences in light acclimation between the two surfaces. With dicots, the abaxial surface had both lower rates of photosynthesis and lower II values than the adaxial surface which may be due to differences in anatomy (spongy versus palisade mesophyll cells) and/or light acclimation between the two surfaces. However, in each species the response of II/CO2 to varying light intensity was similar between the two surfaces, indicating a comparable linkage between PS II activity and CO2 fixation.Abbreviations A
measured rate of CO2 assimilation
- A+RL
true rate of CO2 assimilation; e
- CO2
estimate of electrons transported through PSII per CO2 fixed by RuBP carboxylase
- f
fraction of light absorbed by Photosystem II
- F'm
yield of PSII chlorophyll fluorescence due to a saturating flash of white light under steady-state photosynthesis
- Fs
variable yield of fluorescence under steady-state photosynthesis; PPFD-photosynthetic photon flux density
- Ia
absorbed PPFD
- PS II
Photosystem II
- Rd
rate of respiration in the dark
- RI
rate of respiration in the light estimated from measurement of Rd or from analysis of quantum yields
-
apparent quantum yield of CO2 assimilation under a given condition (A/absorbed PPFD)
-
true quantum yield of CO2 assimilation under a given condition [(A+RL)/(absorbed PPFD)]
-
quantum yield for photosynthetic O2 evolution
-
electrons transported via PS II per quantum absorbed by PS II
Supported by USDA Competitive Grant 90-37280-5706. 相似文献
9.
Effects of Potato Virus YNTN Infection on Gas Exchange and Photosystem 2 Function in Leaves of Solanum tuberosum L. 总被引:1,自引:1,他引:0
Photosynthetic responses of potato (Solanum tuberosum L. cv. Chunzao) were examined during potato virus Y (PVYNTN) infection. PVYNTN infection significantly reduced net photosynthetic rate and stomatal conductance, but had little influence on intercellular CO2 concentration. As the disease developed, the maximum carboxylation velocity of ribulose-1,5-bisphosphate carboxylase/oxygenase and the maximum electron transport rate contributing to ribulose-1,5-bisphosphate regeneration gradually decreased, followed by substantial reductions in the relative quantum efficiency of photosystem 2 (PS2) electron transport, the efficiency of excitation energy capture by open PS2 reaction centres, and photochemical quenching, but not in sustained photoinhibition. Thus PVYNTN depressed photosynthesis mainly by interfering with the enzymatic processes in the Calvin cycle which resulted in a down-regulation of electron transport. 相似文献
10.
A New Approach to Distinguishing Photosynthetic Types of Plants. A Case Study in Northeast China Transect (NECT) Platform 总被引:4,自引:0,他引:4
Discriminant analysis is an important method in multivariable statistic analysis to show what type an individual should belong
to. Based on actual field photosynthetic value set obtained from our research platform, North East China Transect (NECT),
a new approach, developed from the concept and principle of discriminant analysts, was proposed to distinguish C3 and C4 plants. Indices related to plant photosynthetic capacity measured by an LCA4 photosynthesis system were selected to build the discriminant model which is based on four related parameters: net photosynthetic
rate, transpiration rate, stomatal conductance, and difference in temperature between leaf surface and atmosphere. Compared
with other approaches, the present one is fast, straightforward, and efficient.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
The anatomical features of leaves in 11 species of plants grown in a temperature gradient and a temperature + CO2 gradient were studied. The palisade parenchyma thickness, the spongy parenchyma thickness and the total leaf thickness were
measured and analyzed to investigate the effects of elevated temperature and CO2 on the anatomical characteristics of the leaves. Our results show that with the increase of temperature, the leaf thickness
of C4 species increased while the leaf thickness of C3 species showed no constant changes. With increased CO2, seven out of nine C3 species exhibited increased total leaf thickness. In C4 species, leaf thickness decreased. As for the trend on the multi-grades, the plants exhibited linear or non-linear changes.
With the increase of temperature or both temperature and CO2 for the 11 species investigated, leaf thickness varied greatly in different plants (species) and even in different branches
on the same plant. These results demonstrated that the effect of increasing CO2 and temperature on the anatomical features of the leaves were species-specific. Since plant structures are correlated with
plant functions, the changes in leaf anatomical characteristics in elevated temperature and CO2 may lead to functional differences.
Translated from Acta Ecologica Sinica, 2006, 26(2): 326–333 [译自: 生态学报] 相似文献
12.
The response of barley (Hordeum vulgare L. cv. Akcent) to various photosynthetic photon flux densities (PPFDs) and elevated [CO2] [700 μmol (CO2) mol−1; EC] was studied by gas exchange, chlorophyll (Chl) a fluorescence, and pigment analysis. In comparison with barley grown under ambient [CO2] [350 μmol (CO2) mol−1; AC] the EC acclimation resulted in a decrease in photosynthetic capacity, reduced stomatal conductance, and decreased total
Chl content. The extent of acclimation depression of photosynthesis, the most pronounced for the plants grown at 730 μmol
m−2 s−1 (PPFD730), may be related to the degree of sink-limitation. The increased non-radiative dissipation of absorbed photon energy for
all EC plants corresponded to the higher de-epoxidation state of xanthophylls only for PPFD730 barley. Further, a pronounced decrease in photosystem 2 (PS2) photochemical efficiency (given as FV/FM) for EC plants grown at 730 and 1 200 μmol m−2 s−1 in comparison with AC barley was related to the reduced epoxidation of antheraxanthin and zeaxanthin back to violaxanthin
in darkness. Thus the EC conditions sensitise the photosynthetic apparatus of high-irradiance acclimated barley plants (particularly
PPFD730) to the photoinactivation of PS2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
J. -H. Weng 《Photosynthetica》2006,44(3):467-470
Chlorophyll fluorescence parameter Fv/Fm, an indicator of the maximum efficiency of PS2, is routinely measured in the field with plant leaves darkened by leaf clips.
I found that on a sunny day of subtropical summer, the Fv/Fm ratio was often underestimated because of a large F0 value resulted from a high leaf temperature caused by clipping the leaf under high irradiance, especially for long (e.g. 20 min) duration. This phenomenon may overestimate the down-regulation of PS2 efficiency under high irradiance. When leaf
temperature was lower than 40 °C, the F0 level of rice leaves under clipping remained practically unchanged. However, F0 increased drastically with leaf temperature rising over 40 °C. In most measurements, no significant difference in Fm was found between rice leaves dark-adapted by leaf clips for 10 min and for 20 min. Therefore, shading leaf clips to prevent
a drastic increase of leaf temperature, using F0 measured immediately after the leaf being darkened to calculate Fv/Fm, as well as shortening the duration of leaf clipping are useful means to avoid an underestimate of Fv/Fm. 相似文献
14.
The activity of NADP-malate dehydrogenase (NADP-MDH) was determined in the developing first leaf of the C3 plants wheat, barley and pea. Light dependent activation of the enzyme was observed in all three species following rapid extraction and immediate assay. Maximum activity was obtained following extraction from preilluminated leaves and incubation on ice for 45 min in the presence of dithiothreitol. In all three species, maximum activity was obtained in the young leaf 4 days after emergence of the seedling (about 2.5 to 3 moles per milligram chlorophyll per min in wheat and barley, and 6 moles per milligram chlorophyll per min in pea). On a chlorophyll basis there was an approximate five-fold decrease in NADP-MDH activity as the leaf matured. A similar pattern was found for phospho-enolpyruvate carboxylase and NADP-malic enzyme which had maximum activity in younger leaf tissue. Similarly, the activity of nitrate reductase in wheat and barley was high in the young leaf and it rapidly declined as the leaf matured. In contrast, the capacity for photosynthesis was relatively low in the young leaf, reaching a maximum 6 to 8 days after seedling emergence. The pattern of change in activity of phosphoribulokinase, an enzyme of the reductive pentose phosphate pathway, was similar to that of photosynthesis. The results suggest NADP-MDH and phospho-enolpyruvate carboxylase have important function(s) in the young leaf, which are not directly linked to C3 photosynthesis, and which, in part, may be linked to nitrate assimilation and provision of malate to mitochondria.Abbreviations Chl
Chlorophyll
- DTT
Dithiothreitol
- NADP-MDH
NADP-malate Dehydrogenase
- NADP-ME
NADP-malic enzyme 相似文献
15.
Acclimation of foliage photosynthetic properties occurs with varying time kinetics, but structural, chemical and physiological factors controlling the kinetics of acclimation are poorly understood, especially in field environments. We measured chlorophyll fluorescence characteristics, leaf total carotenoid (Car), chlorophyll (Chl) and nitrogen (N) content and leaf dry mass per area (LMA) along vertical light gradients in natural canopies of the herb species, Inula salicina and Centaurea jacea, and tree species, Populus tremula and Tilia cordata, in the middle of the growing season. Presence of stress was assessed on the basis of night measurements of chlorophyll fluorescence. Our aim was to compare the light acclimation of leaf traits, which respond to light availability at long (LMA and N), medium (Chl a/b ratio, Car/Chl ratio) and short time scales (fluorescence characteristics). We found that light acclimation of nitrogen content per unit leaf area (N(area)), chlorophyll content per unit dry mass (Chl(mass)) and Chl/N ratio were related to modifications in LMA. The maximum PSII quantum yield (F(v) /F(m)) increased with increasing growth irradiance in I. salicina and P. tremula but decreased in T. cordata. Leaf growth irradiance, N content and plant species explained the majority of variability in chlorophyll fluorescence characteristics, up to 90% for steady-state fluorescence yield, while the contribution of leaf total carotenoid content was generally not significant. Chlorophyll fluorescence characteristics did not differ strongly between growth forms, but differed among species within a given growth form. These data highlight that foliage acclimation to light is driven by interactions between traits with varying time kinetics. 相似文献
16.
The xanthophyll cycle and the water-water cycle had different functional significance in chilling-sensitive sweet pepper upon exposure to chilling temperature (4 °C) under low irradiance (100 µmol m−2 s−1) for 6 h. During chilling stress, effects of non-photochemical quenching (NPQ) on photosystem 2 (PS2) in dithiothreitol (DTT) fed leaves remained distinguishable from that of the water-water cycle in diethyldithiocarbamate (DDTC) fed leaves. In DTT-fed leaves, NPQ decreased greatly accompanied by visible inhibition of the de-epoxidized ratio of the xanthophyll cycle, and maximum photochemical efficiency of PS2 (Fv/Fm) decreased markedly. Thus the xanthophyll cycle-dependent NPQ could protect PS2 through energy dissipation under chilling stress. However, NPQ had a slighter effect on photosystem 1 (PS1) in DTT-fed leaves than in DDTC-fed leaves, whereas effects of the water-water cycle on PS1 remained distinguishable from that of NPQ. Inhibiting superoxide dismutase (SOD) activity increased the accumulation of
, the oxidation level of P700 (P700+) decreased markedly relative to the control and DTT-fed leaves. Both Fv/Fm and NPQ changed little in DDTC-fed leaves accompanied by little change of (A+Z)/(V+A+Z). This is the active oxygen species inducing PS1 photoinhibition in sweet pepper. The water-water cycle can be interrupted easily at chilling temperature. We propose that during chilling stress under low irradiance, the xanthophyll cycle-dependent NPQ has the main function to protect PS2, whereas the water-water cycle is not only the pathway to dissipate energy but also the dominant factor causing PS1 chilling-sensitivity in sweet pepper.This research was supported by the State Key Basic Research and Development Plan of China (G1998010100), the Natural Science Foundation of China (30370854), and the open project from Key Lab of Crop Biology of Shandong Province. 相似文献
17.
The postillumination burst (PIB) of CO2 and light-enhanced dark respiration (LEDR) depending on oxygen concentration, temperature, respiratory substrates and photorespiratory
inhibitor aminoacetonitrile (AAN) were investigated in detached leaves of tall fescue (Festuca arundinacea) using a closed circuit system with an infrared gas analyzer. No PIB was observed in 1 % O2 under temperature over the range from 15 °C to 35 °C. The rate of LEDR was about twice as low in 1 % O2 as that in 21 and 50 % O2 under all temperatures applied. The PIB was absent and LEDR decreased at 21 % O2 following illumination of leaves for 1 hour at 1 % O2. When 200 mM glycine or malate solutions were introduced into the leaves of tall fescue, the magnitudes of PIB increased
by about 60 and 40 % and rate of LEDR by about 70 % and 40 %, respectively. Pyruvate and succinate were less effective in
promotion of PIB and LEDR. AAN had a small stimulatory effect on PIB and LEDR (about 20 % and 10 %, respectively). The dependences
between magnitudes of PIB and rates of LEDR were highly correlated (r=0.94). The results presented indicate that atmospheric
concentration of oxygen during the period of photosynthesis of tall fescue leaves was necessary not only for occurrence of
PIB and LEDR but also for production of substrate(s) (glycine and/or malate) for these phenomena. 相似文献
18.
Physiological Basis of the Difference in Net Photosynthetic Rate of Leaves between Two Maize Strains 总被引:3,自引:0,他引:3
Significant differences in net photosynthetic rate (P
N) of leaves between two maize (Zea mays L.) strains (Shuang 105 and 40×44) grown in the field were observed. At several growth stages, P
N of 40×44 was higher than that of Shuang 105 (from 10.3 to 32.5 %). Moreover, the strain 40×44 had a higher plant height, larger leaf area, lower chlorophyll content, and higher photochemical efficiency of photosystem 2 (PS2) (Fv/Fm and F/Fm) than strain Shuang 105. Shuang 105, which showed lower P
N, had lower stomatal conductances (g
s) but slightly higher intercellular CO2 concentrations (C
i) than those of 40×44. Hence the differences in P
N between the two strains did not result from the difference in g
s, but probably from that in light reaction system. 相似文献
19.
20.
Foliar δ13C values of Calligogum kozlovi and Haloxylon ammodendron ranged from −13.13 to −15.11 ‰, while those of the rest 11 species were in the range of −22.22 to −27.73 ‰. This indicates
that two of 13 dominant plant species in the Qaidam Basin possess a C4 photosynthetic pathway. Significant differences were observed for the average foliar δ13C values between C3 or C4 plant communities, between grass and shrub communities, even between the same species derived from different sites. Precipitation
accounted for the major part of the differences. 相似文献