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1.
The emission of molecular iodine (I2) from the stipe, the meristematic area and the distal blade of the brown macroalga Laminaria digitata (Hudson) Lamouroux (Phaeophyceae) was monitored under low light and dark conditions. Photosynthetic parameters were determined
to investigate both the extent of stress experienced by different thallus parts and the effects of emersion on photosynthesis.
Immediately after air exposure, intense I2 emission was detectable from all thallus parts. I2 emission declined continuously over a period of 180 min following the initial burst, but was not affected by the light regime.
The total number of mole of I2 emitted by stipes was approximately 10 times higher than those emitted from other thallus parts. Initial I2 emission rates (measured within 30 min of exposure to air) were highest for stipes (median values: 2,999 and 5,222 pmol g−1 dw min−1 in low light and dark, respectively) and lower, by one order of magnitude, for meristematic regions and distal blades. After
exposure to air for between 60 and 180 min, I2 emission rates of all thallus parts were reduced by 70–80%. Air exposure resulted in a decrease of the maximum photosystem
II (PSII) efficiency (F
v/F
m) by 3%, and in a 25–55% increase of the effective PSII quantum efficiency (
\Updelta F/F¢\textm \Updelta F/F^{\prime}_{\text{m}} ); this was caused by a higher fraction of open reaction centres (qP), whereas the efficiency of the latter in capturing energy (
F¢\textv /F¢\textm F^{\prime}_{\text{v}} /F^{\prime}_{\text{m}} ) remained constant. The results indicate the presence of an iodine pool which is easily volatilised and depleted due to air
exposure, even under apparently low stress conditions. 相似文献
2.
The photosystem II (PSII) manganese-stabilizing protein (PsbO) is known to be the essential PSII extrinsic subunit for stabilization
and retention of the Mn and Cl− cofactors in the oxygen evolving complex (OEC) of PSII, but its function relative to Ca2+ is less clear. To obtain a better insight into the relationship, if any, between PsbO and Ca2+ binding in the OEC, samples with altered PsbO-PSII binding properties were probed for their potential to promote the ability
of Ca2+ to protect the Mn cluster against dark-inhibition by an exogenous artificial reductant, N,N-dimethylhydroxylamine. In the absence of the PsbP and PsbQ extrinsic subunits, Ca2+ and its surrogates (Sr2+, Cd2+) shield Mn atoms from inhibitory reduction (Kuntzleman et al., Phys Chem Chem Phys 6:4897, 2004). The results presented here show that PsbO exhibits a positive effect on Ca2+ binding in the OEC by facilitating the ability of the metal to prevent inhibition of activity by the reductant. The data
presented here suggest that PsbO may have a role in the formation of the OEC-associated Ca2+ binding site by promoting the equilibrium between bound and free Ca2+ that favors the bound metal. 相似文献
3.
Kinetics of styrene biodegradation by <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. E-93486 总被引:1,自引:0,他引:1
The research into kinetics of styrene biodegradation by bacterial strain Pseudomonas sp. E-93486 coming from VTT Culture Collection (Finland) was presented in this work. Microbial growth tests in the presence
of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. Batch experiments were
conducted for initial concentration of styrene in the liquid phase changed in the range of 5–90 g m−3. The Haldane model was found to be the best to fit the kinetic data, and the estimated constants of the equation were: μ
m = 0.1188 h−1, K
S = 5.984 mg l−1, and K
i = 156.6 mg l−1. The yield coefficient mean value
Y\textxs\textapp Y_{\text{xs}}^{\text{app}} for the batch culture was 0.72 gdry cells weight (gsubstrate)−1. The experiments conducted in a chemostat at various dilution rates (D = 0.035–0.1 h−1) made it possible to determine the value of the coefficient for maintenance metabolism m
d = 0.0165 h−1 and the maximum yield coefficient value
Y\textxs\textM = 0.913 Y_{\text{xs}}^{\text{M}} = 0.913 . Chemostat experiments confirmed the high value of yield coefficient
Y\textxs\textapp Y_{\text{xs}}^{\text{app}} observed in the batch culture. The conducted experiments showed high activity of the examined strain in the styrene biodegradation
process and a relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution.
Such exceptional features of Pseudomonas sp. E-93486 make this bacterial strain the perfect candidate for technical applications. 相似文献
4.
5.
Toxic at low concentrations, phenol is one of the most common organic pollutants in air and water. In this work, phenol biodegradation
was studied in extreme conditions (80°C, pH = 3.2) in a 2.7 l bioreactor with the thermoacidophilic archaeon Sulfolobus solfataricus 98/2. The strain was first acclimatized to phenol on a mixture of glucose (2000 mg l−1) and phenol (94 mg l−1) at a constant dissolved oxygen concentration of 1.5 mg l−1. After a short lag-phase, only glucose was consumed. Phenol degradation then began while glucose was still present in the
reactor. When glucose was exhausted, phenol was used for respiration and then for biomass build-up. After several batch runs
(phenol < 365 mg l−1), specific growth rate (μX) was 0.034 ± 0.001 h−1, specific phenol degradation rate (qP) was 57.5 ± 2 mg g−1 h−1, biomass yield (YX/P) was 52.2 ± 1.1 g mol−1, and oxygen yield factor
( \textY\textX/\textO 2 ) \left( {{\text{Y}}_{{{\text{X}}/{\text{O}}_{ 2} }} } \right) was 9.2 ± 0.2 g mol−1. A carbon recovery close to 100% suggested that phenol was exclusively transformed into biomass (35%) and CO2 (65%). Molar phenol oxidation constant
( \textY\textO 2 /\textP ) \left( {{\text{Y}}_{{{\text{O}}_{ 2} /{\text{P}}}} } \right) was calculated from stoichiometry of phenol oxidation and introducing experimental biomass and CO2 conversion yields on phenol, leading to values varying between 4.78 and 5.22 mol mol−1. Respiratory quotient was about 0.84 mol mol−1, very close to theoretical value (0.87 mol mol−1). Carbon dioxide production, oxygen demand and redox potential, monitored on-line, were good indicators of growth, substrate
consumption and exhaustion, and can therefore be usefully employed for industrial phenol bioremediation in extreme environments. 相似文献
6.
This minireview summarizes the current state of knowledge concerning the role of Cl− in the oxygen-evolving complex (OEC) of photosystem II (PSII). The model that proposes that Cl− is a Mn ligand is discussed in light of more recent work. Studies of Cl− specificity, stoichiometry, kinetics, and retention by extrinsic polypeptides are discussed, as are the results that fail
to detect Cl− ligation to Mn and results that show a lack of a requirement for Cl− in PSII-catalyzed H2O oxidation. Mutagenesis experiments in cyanobacteria and higher plants that produce evidence for a correlation between Cl− retention and stable interactions among intrinsic and extrinsic polypeptides are summarized, and spectroscopic data on the
interaction between PSII and Cl− are discussed. Lastly, the question of the site of Cl− action in PSII is discussed in connection with the current crystal structures of the enzyme. 相似文献
7.
P. M. Paes de Sousa D. Rodrigues C. G. Timóteo M. L. Simões Gonçalves G. W. Pettigrew I. Moura J. J. G. Moura M. M. Correia dos Santos 《Journal of biological inorganic chemistry》2011,16(6):881-888
The activation mechanism of Pseudomonas stutzeri cytochrome c peroxidase (CCP) was probed through the mediated electrochemical catalysis by its physiological electron donor, P. stutzeri cytochrome c-551. A comparative study was carried out, by performing assays with the enzyme in the resting oxidized state as well as in
the mixed-valence activated form, using cyclic voltammetry and a pyrolytic graphite membrane electrode. In the presence of
both the enzyme and hydrogen peroxide, the peak-like signal of cytochrome c-551 is converted into a sigmoidal wave form characteristic of an
\textE\textr \textC\texti¢ {\text{E}}_{\text{r}} {\text{C}}_{\text{i}}^{\prime } catalytic mechanism. An intermolecular electron transfer rate constant of (4 ± 1) × 105 M−1 s−1 was estimated for both forms of the enzyme, as well as a similar Michaelis–Menten constant. These results show that neither
the intermolecular electron transfer nor the catalytic activity is kinetically controlled by the activation mechanism of CCP
in the case of the P. stutzeri enzyme. Direct enzyme catalysis using protein film voltammetry was unsuccessful for the analysis of the activation mechanism,
since P. stutzeri CCP undergoes an undesirable interaction with the pyrolytic graphite surface. This interaction, previously reported for the
Paracoccus pantotrophus CCP, induces the formation of a non-native conformation state of the electron-transferring haem, which has a redox potential
200 mV lower than that of the native state and maintains peroxidatic activity. 相似文献
8.
A convenient and effective way for fabricating amperometric hydrogen peroxide (H2O2) biosensor was designed in this paper. First, the polyaniline (PANI) nanofibers membrane with good conductance and high surface
area was electropolymerized on a gold electrode surface. Then, Pt nanoparticle (PtNP) was electrochemically deposited on the
PANI nanofibers membrane. Finally, the hybrid film of gold nanoparticle, chitosan, and horseradish peroxidase (HRP) was cast
onto the modified electrode to form a stable biofunctional film, which was also employed as a protective layer to PtNP. The
proposed biosensor exhibited a rapid response to H2O2 with the linear range from 7.0 × 10−6 to 1.4 × 10−2 M and a detection limit of 2.8 × 10−6 M (S/N = 3). The sensitivity of 558 μA mM−1 cm−2 was obtained. The Michaelis–Menten constant,
K\textM\textapp K_{\text{M}}^{\text{app}} value was 1.90 mM suggesting a high affinity. Moreover, it displayed a good reproducibility and long-term stability. 相似文献
9.
A study of heat effects was performed in thylakoids and photosystem II (PSII)-enriched membranes isolated from spinach in
relation to Cl−-induced activation of PSII catalyzed oxygen evolution and the retention of Cl− in the PSII complex. For this, Cl−-sufficient membranes and low-Cl− membranes were used. The presence of Cl− in the reaction medium did accelerate oxygen evolution, which remained unaffected by heat treatment up to 40°C in PSII membranes
and up to 42.5°C in thylakoids. Heat resistance of Cl−-induced activation of oxygen evolution was found to be independent of the presence of ‘bound Cl−’ in the preparations. However, the functional stability of the PSII complex during heat treatment showed a marked dependence
on the presence of bound Cl− in PSII. Electron paramagnetic resonance study of manganese (Mn) release per reaction center/YD+ showed that there was little loss of Mn2+ up to 42°C in our preparations, although the PSII activity was significantly lowered. These observations together with data
from steady state chlorophyll a fluorescence imply that the site of action of Cl− causing direct activation of oxygen evolution was different from the site of primary heat damage. A differential response
of chloride binding sites to heat stress was observed. The high-affinity (tightly bound, slow exchanging) site of chloride
is affected earlier (∼37°C) while low-affinity (loosely bound, fast exchanging) site gets affected at higher temperatures
(42.5°C in thylakoids and 40°C in the case of PSII-enriched membranes).
Prasanna Mohanty is an INSA Honorary Scientist and Professor on Courtesy, DAVV, Indore. 相似文献
10.
Wim J. Vredenberg 《Photosynthesis research》2009,102(1):99-101
Quantitative data on laser flash-induced variable fluorescence in the 100 ns to 1 ms time range (Belyaeva et al. in Photosynth
Res 98:105–119, 2008) confirming those of others (Steffen et al. in Biochemistry 40:173–180, 2001, Biochemistry 44:3123–3132, 2005; Belyaeva et al. in Biophysics 51(6):976–990, 2006), need a substantial correction with respect to magnitude of the normalized variable fluorescence associated with single
turnover-induced charge separation in RCs of PS II. Their data are conclusive with the involvement of donor side quenching,
the release of which occurs with a rate constant in the range of tens of ms−1, and presumed to be associated with reduction of
Y\textz + Y_{\text{z}}^{ + } by the OEC. 相似文献
11.
Described here is a set of three-dimensional (3D) NMR experiments that rely on CACA-TOCSY magnetization transfer via the weak
3 \textJ\textCa\textCa ^{ 3} {\text{J}}_{{{\text{C}}\alpha {\text{C}}\alpha }} coupling. These pulse sequences, which resemble recently described 13C detected CACA-TOCSY (Takeuchi et al. 2010) experiments, are recorded in 1H2O, and use 1H excitation and detection. These experiments require alternate 13C-12C labeling together with perdeuteration, which allows utilizing the small
3 \textJ\textCa\textCa ^{ 3} {\text{J}}_{{{\text{C}}\alpha {\text{C}}\alpha }} scalar coupling that is otherwise masked by the stronger 1JCC couplings in uniformly 13C labeled samples. These new experiments provide a unique assignment ladder-mark that yields bidirectional supra-sequential
information and can readily straddle proline residues. Unlike the conventional HNCA experiment, which contains only sequential
information to the
1 3 \textCa ^{ 1 3} {\text{C}}^{\alpha } of the preceding residue, the 3D hnCA-TOCSY-caNH experiment can yield sequential correlations to alpha carbons in positions
i−1, i + 1 and i−2. Furthermore, the 3D hNca-TOCSY-caNH and Hnca-TOCSY-caNH experiments, which share the same magnetization pathway but use
a different chemical shift encoding, directly couple the 15N-1H spin pair of residue i to adjacent amide protons and nitrogens at positions i−2, i−1, i + 1 and i + 2, respectively. These new experimental features make protein backbone assignments more robust by reducing the degeneracy problem
associated with the conventional 3D NMR experiments. 相似文献
12.
Tropical plants are sensitive to chilling temperatures above zero but it is still unclear whether photosystem I (PSI) or photosystem
II (PSII) of tropical plants is mainly affected by chilling temperatures. In this study, the effect of 4°C associated with
various light densities on PSII and PSI was studied in the potted seedlings of four tropical evergreen tree species grown
in an open field, Khaya ivorensis, Pometia tomentosa, Dalbergia odorifera, and Erythrophleum guineense. After 8 h chilling exposure at the different photosynthetic flux densities of 20, 50, 100, 150 μmol m−2 s−1, the maximum quantum yield of PSII (F
v
/F
m) in all of the four species decreased little, while the quantity of efficient PSI complex (P
m) remained stable in all species except E. guineense. However, after chilling exposure under 250 μmol m−2 s−1 for 24 h, F
v
/F
m was severely photoinhibited in all species whereas P
m was relative stable in all plants except E. guineense. At the chilling temperature of 4°C, electron transport from PSII to PSI was blocked because of excessive reduction of primary
electron acceptor of PSII. F
v
/F
m in these species except E. guineense recovered to ~90% after 8 h recovery in low light, suggesting the dependence of the recovery of PSII on moderate PSI and/or
PSII activity. These results suggest that PSII is more sensitive to chilling temperature under the moderate light than PSI
in tropical trees, and the photoinhibition of PSII and closure of PSII reaction centers can serve to protect PSI. 相似文献
13.
The oxygen-evolving complex (OEC) of higher plant photosystem II (PSII) consists of an inorganic Mn4Ca cluster and three nuclear-encoded proteins, PsbO, PsbP and PsbQ. In this review, we focus on the assembly of these OEC
proteins, and especially on the role of the small intrinsic PSII proteins and recently found “novel” PSII proteins in the
assembly process. The numerous auxiliary functions suggested during the past few years for the OEC proteins will likewise
be discussed. For example, besides being a manganese-stabilizing protein, PsbO has been found to bind calcium and GTP and
possess a carbonic anhydrase activity. In addition, specific roles have been suggested for the two isoforms of the PsbO protein
in Arabidopsis thaliana. PsbP and PsbQ seem to play an additional role in the formation of PSII supercomplexes and in grana stacking, besides their
originally recognized role in providing a proper calcium and chloride ion concentration for water splitting. 相似文献
14.
15.
By simultaneously analyzing the chlorophyll a fluorescence transient and light absorbance at 820 nm as well as chlorophyll fluorescence quenching, we investigated the
effects of different photon flux densities (0, 15, 200 μmol m−2 s−1) with or without 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on the repair process of cucumber (Cucumis sativus L.) leaves after treatment with low temperature (6°C) combined with moderate photon flux density (200 μmol m−2 s−1) for 6 h. Both the maximal photochemical efficiency of Photosystem II (PSII) (F
v/F
m) and the content of active P700 (ΔI/I
o) significantly decreased after chilling treatment under 200 μmol m−2 s−1 light. After the leaves were transferred to 25°C, F
v/F
m recovered quickly under both 200 and 15 μmol m−2 s−1 light. ΔI/I
o recovered quickly under 15 μmol m−2 s−1 light, but the recovery rate of ΔI/I
o was slower than that of F
v/F
m. The cyclic electron transport was inhibited by chilling-light treatment obviously. The recovery of ΔI/I
o was severely suppressed by 200 μmol m−2 s−1 light, whereas a pretreatment with DCMU effectively relieved this suppression. The cyclic electron transport around PSI recovered
in a similar way as the active P700 content did, and the recovery of them was both accelerated by pretreatment with DCMU.
The results indicate that limiting electron transport from PSII to PSI protected PSI from further photoinhibition, accelerating
the recovery of PSI. Under a given photon flux density, faster recovery of PSII compared to PSI was detrimental to the recovery
of PSI or even to the whole photosystem. 相似文献
16.
Jiří Masojídek Jiří Kopecký Luca Giannelli Giuseppe Torzillo 《Journal of industrial microbiology & biotechnology》2011,38(2):307-317
This work aims to: (1) correlate photochemical activity and productivity, (2) characterize the flow pattern of culture layers
and (3) determine a range of biomass densities for high productivity of the freshwater microalga Chlorella spp., grown outdoors in thin-layer cascade units. Biomass density, irradiance inside culture, pigment content and productivity
were measured in the microalgae cultures. Chlorophyll-fluorescence quenching was monitored in situ (using saturation-pulse
method) to estimate photochemical activities. Photobiochemical activities and growth parameters were studied in cultures of
biomass density between 1 and 47 g L−1. Fluorescence measurements showed that diluted cultures (1–2 g DW L−1) experienced significant photostress due to inhibition of electron transport in the PSII complex. The highest photochemical
activities were achieved in cultures of 6.5–12.5 g DW L−1, which gave a maximum daylight productivity of up to 55 g dry biomass m−2 day−1. A midday depression of maximum PSII photochemical yield (F
v/F
m) of 20–30% compared with morning values in these cultures proved to be compatible with well-performing cultures. Lower or
higher depression of F
v/F
m indicated low-light acclimated or photoinhibited cultures, respectively. A hydrodynamic model of the culture demonstrated
highly turbulent flow allowing rapid light/dark cycles (with frequency of 0.5 s−1) which possibly match the turnover of the photosynthetic apparatus. These results are important from a biotechnological point
of view for optimisation of growth of outdoor microalgae mass cultures under various climatic conditions. 相似文献
17.
Photosynthetic Potential and its Association with Lipid Peroxidation in Response to High Temperature at Different Leaf Ages in Maize 总被引:2,自引:0,他引:2
Zhenzhu Xu Guangsheng Zhou Guangxuan Han Yijun Li 《Journal of Plant Growth Regulation》2011,30(1):41-50
High temperature generally constrains plant growth and photosynthesis in many regions of the world; however, little is known
about how photosynthesis responds to high temperature with regard to different leaf ages. The synchronous changes in gas exchange
and chlorophyll fluorescence at three leaf age levels (just fully expanded, mature, and older leaves) of maize (Zea mays L.) were determined at three temperatures (30°C as a control and 36 and 42°C as the higher temperatures). High temperature
significantly decreased the net CO2 assimilation rate (A), stomatal conductance (g
s), maximal efficiency of photosystem II (PSII) photochemistry (F
v/F
m), efficiency of excitation energy capture by open PSII reaction centers (
F¢\textv /F¢\textm F^{\prime}_{\text{v}} /F^{\prime}_{\text{m}} ), photochemical quenching of variable chlorophyll fluorescence (q
P), and the electron transport rate (ETR), whereas minimal fluorescence yield (F
0) and nonphotochemical quenching of variable chlorophyll fluorescence (q
N) were increased. The youngest fully expanded leaves had higher A, ETR, and q
P compared with older leaves. Higher temperature with old leaves led to significant malondialdehyde (MDA) accumulation, a proxy
for lipid peroxidation damage from active oxygen species (AOS). MDA content was significantly negatively correlated with A, F
v/F
m,
F¢\textv /F¢\textm F^{\prime}_{\text{v}} /F^{\prime}_{\text{m}} , and q
P. Thus, the results suggest that photosynthetic potentials, including stomatal regulation and PSII activity, may be restricted
at high temperature, together with increasing cell peroxidation, which may be closely associated with leaf age. 相似文献
18.
Physiological characterization of ‘stay green’ wheat cultivars during the grain filling stage under field growing conditions 总被引:1,自引:0,他引:1
Junbo Chen Yun Liang Xueyun Hu Xianxiang Wang Feiquan Tan Huaiqiong Zhang Zhenglong Ren Peigao Luo 《Acta Physiologiae Plantarum》2010,32(5):875-882
Rye (Secale cereale L.) chromosome arm 1RS could delay leaf senescence, and change in H2O2 content is a useful index for weighing the ability to delay the senescence. Two wheat cultivars, Chuannong12 (CN12) and Chuannong
18 (CN18), harboring the wheat–rye 1BL/1RS translocated chromosome were investigated for H2O2 change and physiological index after flowering under field conditions, and MY11, the agronomical parent of both CN12 and
CN18, was used as the control. A combined change in the peak value of CdSe/ZnS quantum dot (QD) fluorescence and morphological
observation indicated that the H2O2 contents in CN12 and CN18 were generally lower than that in MY11. They both had higher values for net photosynthetic rate
(P
n), stomatal conductance (G
s),
F\textv /F\textm¢ F_{\text{v}} /F_{\text{m}}^{\prime }
F\textv¢ /F\textm¢ F_{\text{v}}^{\prime } /F_{\text{m}}^{\prime } , and photochemical quenching of PSII (qP) than MY11 only in the late measurement stage. Some small differences were also
observed, such as CN12 and CN18 wheat cultivars having higher and longer photosynthetic competence than MY11 during the grain
filling stage, which perhaps resulted from a mechanism for removing oxidative species, especially H2O2. 相似文献
19.
Chunhui Cao Shichun Sun Xuekui Wang Wenling Liu Ying Liang 《Journal of applied phycology》2011,23(6):1039-1043
Experimental ecology methods and chlorophyll fluorescence technology were used to study the effects of different concentrations
of manganese (10−12– 10−4 mol L−1) on the growth, photosystem II and superoxide dismutase (SOD) activity of Amphidinium sp. MACC/D31. The results showed that manganese had a significant effect on the growth rate, fluorescence parameters (maximal
photochemical efficiency of PSII (F
v
/F
m
), photochemical quenching (qP) and non-photochemical quenching (NPQ)) in the exponential stage (days 1–3) and SOD activity
of Amphidinium sp. (P < 0.05). F
v/F
m in the exponential stage in 10−12 mol L−1 manganese concentration was significantly lower whilst qP and NPQ significantly higher than those in the other concentrations.
F
v
/F
m
(days 6–9) in 10−4 mol L−1 manganese was significantly higher than those in the other concentrations. F
v
/F
m
(days 3–6) increased with increased concentration of manganese from 10−12 to 10−4 mol L−1. The values of qP and NPQ decreased with decreased concentrations of manganese, except for those in days 4–6. F
v
/F
m
under each concentration increased earlier and decreased later with culture stage whilst NPQ decreased earlier and increased
later. The SOD activity increased with increased concentration of manganese from 10−12 to 10−8 mol L−1. The SOD activity in 10−4 mol L−1 manganese was significantly higher than those in the other concentrations and in 10−12 mol L−1 manganese, it was significantly lower than those in the other concentrations. 相似文献
20.
Simultaneous measurements of chlorophyll (Chl) fluorescence and CO2 assimilation (A) in Vicia faba leaves were taken during the first weeks of growth to evaluate the protective effect of 24-epibrassinolide (EBR) against
damage caused by the application of the herbicide terbutryn (Terb) at pre-emergence. V. faba seeds were incubated for 24 h in EBR solutions (2 × 10−6 or 2 × 10−5 mM) and immediately sown. Terb was applied at recommended doses (1.47 or 1.96 kg ha−1) at pre-emergence. The highest dose of Terb strongly decreased CO2 assimilation, the maximum quantum yield of PSII photochemistry in the dark-adapted state (F
V/F
M), the nonphotochemical quenching (NPQ), and the effective quantum yield (ΔF/F′M) during the first 3–4 weeks after plant emergence. Moreover, Terb increased the basal quantum yield of nonphotochemical processes
(F
0/F
M), the degree of reaction center closure (1 − q
p), and the fraction of light absorbed in PSII antennae that was dissipated via thermal energy dissipation in the antennae
(1 − F′V/F′M). The herbicide also significantly reduced plant growth at the end of the experiment as well as plant length, dry weight,
and number of leaves. The application of EBR to V. faba seeds before sowing strongly diminished the effect of Terb on fluorescence parameters and CO2 assimilation, which recovered 13 days after plant emergence and showed values similar to those of control plants. The protective
effect of EBR on CO2 assimilation was detected at a photosynthetic photon flux density (PFD) of 650 μmol m−2 s−1 and the effect on ΔF/F′M and photosynthetic electron transport (J) was detected under actinic lightings up to 1750 μmol m−2 s−1. The highest dose of EBR also counteracted the decrease in plant growth caused by Terb, and plants registered the same growth
values as controls. 相似文献