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1.
Nitraria retusa and Atriplex halimus (xero-halophytes) plants were grown in the range 0–800 mM NaCl while Medicago arborea (glycophyte) in 0–300 mM NaCl. Salt stress caused a marked decrease in osmotic potential and a significant accumulation of
Na+ and Cl− in leaves of both species. Moderate salinity had a stimulating effect on growth rate, net CO2 assimilation, transpiration and stomatal conductance for the xero-halophytic species. At higher salinities, these physiological
parameters decreased significantly, and their percentages of reduction were higher in A. halimus than in N. retusa whereas, in M. arborea they decreased linearly with salinity. Nitraria retusa PSII photochemistry and carotenoid content were unaffected by salinity, but a reduction in chlorophyll content was observed
at 800 mM NaCl. Similar results were found in A. halimus, but with a decrease in the efficiency of PSII (F′v/F′m) occurred at 800 mM. Conversely, in M. arborea plants we observed a significant reduction in pigment concentrations and chlorophyll fluorescence parameters. The marked
toxic effect of Na+ and/or Cl− observed in M. arborea indicates that salt damage effect could be attributed to ions’ toxicity, and that the reduction in photosynthesis is most
probably due to damages in the photosynthetic apparatus rather than factors affecting stomatal closure. For the two halophyte
species, it appears that there is occurrence of co-limitation of photosynthesis by stomatal and non-stomatal factors. Our
results suggest that both N. retusa and A. halimus show high tolerance to both high salinity and photoinhibition while M. arborea was considered as a slightly salt tolerant species. 相似文献
2.
The effects of NaCl stress on growth, water status, contents of protein, proline, malondialdehyde (MDA), various sugars and
photosynthetic pigments were investigated in seedlings of Salicornia persica and S. europaea grown in vitro. Seeds were germinated under NaCl (0, 100, 200, 300, 400, 500 and 600 mM) on Murashige and Skoog medium for 45 d. The shoot
growth of both species increased under low NaCl concentration (100 mM) and then decreased with increasing NaCl concentrations.
In contrast to S. persica, root length in S. europaea reduced steadily with an increase in salinity. Proline content in S. persica was higher than in S. europaea at most NaCl concentrations. Proline, reducing saccharide, oligosaccharide and soluble saccharide contents increased under
salinity in both species. In contrast, contents of proteins and polysaccharides reduced in both species under salt stress.
MDA content remained close to control at moderate NaCl concentrations (100 and 200 mM) and increased at higher salinities.
MDA content in S. europaea was significantly higher than S. persica at higher salinities. Salt treatments decreased K+ and P contents in seedlings of both species. Significant reduction in contents of chlorophylls and carotenoids due to NaCl
stress was also observed in seedlings of both species. Some differences appeared between S. persica and S. europaea concerning proteins profile. On the basis of the data obtained, S. persica is more salt-tolerant than S. europaea. 相似文献
3.
Ozone depletion is highest during spring and summer in Antarctica, coinciding with the seasonal reproduction of most macroalgae.
Propagules are the life-stage of an alga most susceptible to environmental perturbations therefore, reproductive cells of
three intertidal macroalgal species Adenocystis utricularis (Bory) Skottsberg, Monostroma hariotii Gain, and Porphyra endiviifolium (A and E Gepp) Chamberlain were exposed to photosynthetically active radiation (PAR), PAR + UV-A and PAR + UV-A + UV-B radiation
in the laboratory. During 1, 2, 4, and 8 h of exposure and after 48 h of recovery, photosynthetic efficiency, and DNA damage
were determined. Saturation irradiance of freshly released propagules varied between 33 and 83 μmol photons m−2 s−1 with lowest values in P. endiviifolium and highest values in M. hariotii. Exposure to 22 μmol photons m−2 s−1 PAR significantly reduced photosynthetic efficiency in P. endiviifolium and M. hariotii, but not in A. utricularis. UV radiation (UVR) further decreased the photosynthetic efficiency in all species but all propagules recovered completely
after 48 h. DNA damage was minimal or not existing. Repeated exposure of A. utricularis spores to 4 h of UVR daily did not show any acclimation of photosynthesis to UVR but fully recovered after 20 h. UVR effects
on photosynthesis are shown to be species-specific. Among the tested species, A. utricularis propagules were the most light adapted. Propagules obviously possess good repair and protective mechanisms. Our study indicates
that the applied UV dose has no long-lasting negative effects on the propagules, a precondition for the ecological success
of macroalgal species in the intertidal. 相似文献
4.
Rym Ben Dhiab Hatem Ben Ouada Hamadi Boussetta Fabrice Franck Amor Elabed Michel Brouers 《Journal of applied phycology》2007,19(4):293-301
The effect of salt concentration (NaCl) on growth, fluorescence, photosynthetic activities and pigment content of the cyanobacterium
Arthrospira platensis has been investigated over 15 days. It has been observed that high NaCl concentration induces an increase of the growth,
photosynthetic efficiency (α), phycobilin/chlorophyll ratio and a slight decrease of dark respiration and compensation points.
Moreover, high NaCl concentration enhances photosystem II (PSII) activity compared to photosystem I (PSI). Results show that
the phycobilin-PSII energy transfer compared to the chlorophyll-PSII (F695,600/F695,440) increases. However, data obtained about the maximal efficiency of PSII photochemistry are controversial. Indeed, the Fv/Fm
ratio decreases in salt adapted cultures, while at the same time the trapping flux per PSII reaction center (TR0/RC) and the probability of electron transport beyond QA (0) remain unchanged at the level of the donor and the acceptor sites of PSII. This effect can be attributed to the interference
of phycobilin fluorescence with Chl a when performing polyphasic transient measurements. 相似文献
5.
Mónica Calvo-Polanco Melanie D. Jones Janusz J. Zwiazek 《Acta Physiologiae Plantarum》2009,31(3):515-522
In the present study, we investigated the effects of pH treatments on NaCl tolerance in mycorrhizal and non-mycorrhizal American
elm. American elm (Ulmus americana) seedlings were inoculated with Hebeloma crustuliniforme, Laccaria bicolor or with both mycorrhizal fungi and subsequently subjected to different pH solutions (pH 3, 6 and 9) containing 0 mM (control)
and 60 mM NaCl for 4 weeks. Inoculation with the mycorrhizal fungi did not have a large effect on seedling dry weights when
the pH and NaCl treatments were considered independently. However, when the inoculated seedlings were treated with 60 mM NaCl
at pH 3 or 6, shoot to root ratios and root hydraulic conductivity were higher compared with non-inoculated plants, likely
reflecting changes in seedling water flow properties. At pH 6, transpiration rates were about twofold lower in non-inoculated
plants treated with NaCl compared with non-treated controls. For NaCl-treated H. crustuliniforme- and L. bicolor-inoculated plants, the greatest reduction of transpiration rates was at pH 9. Treatment with 60 mM NaCl reduced leaf chlorophyll
concentrations more in non-inoculated compared with inoculated plants, with the greatest, twofold, decrease occurring at pH
6. At pH 3, root Na concentrations were higher in inoculated than non-inoculated seedlings; however, there was no effect of
inoculation on root Na concentrations at pH 6 and 9. Contrary to the roots, the leaves of inoculated plants had lower Na concentrations
at pH 6 and 9, but not at pH 3. The results point to an interaction between ECM fungi and root zone pH for salt tolerance
of American elm. 相似文献
6.
Mohammad Aghaleh Vahid Niknam Hassan Ebrahimzadeh Khadijeh Razavi 《Acta Physiologiae Plantarum》2011,33(4):1261-1270
The effects of salt stress on growth parameters, free proline content, ion accumulation, lipid peroxidation, and several antioxidative
enzymes activities were investigated in S. persica and S. europaea. The seedlings were grown for 2 months in half-strength Hoagland solution and treated with different concentrations of NaCl
(0, 85, 170, 340, and 510 mM) for 21 days. The fresh and dry weights of both species increased significantly at 85 and 170 mM
NaCl and decreased at higher concentrations. Salinity increased proline content in both the species as compared to that of
control. Sodium (Na+) content in roots and shoots increased, whereas K+ and Pi content in both organs decreased. At all NaCl concentrations, the total amounts of Na+ and K+ were higher in shoots than in roots. Malondialdehyde (MDA) content declined at moderate NaCl concentrations (85 and 170 mM)
and increased at higher levels. With increased salinity, superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase
(GPX) activities also increased gradually in both species. In addition, it seems that GPX, CAT, and SOD activities play an
essential protective role in the scavenging reactive oxygen species (ROS) in both species. Native polyacrylamide gel electrophoresis
(PAGE) indicated different isoform profiles between S. persica and S. europaea concerning antioxidant enzymes. These results showed that S. persica exhibits a better protection mechanism against oxidative damage and it is more salt-tolerant than S. europaea possibly by maintaining and/or increasing growth parameters, ion accumulation, and antioxidant enzyme activities. 相似文献
7.
An hydroponic culture was conducted to investigate the effect of saline stress on the essential oil and fatty acid composition
of Tunisian coriander (Coriandrum sativum L.) roots. Ten days old coriander seedlings were treated during 3 weeks with different NaCl concentrations (0, 25, 50 and
75 mM). Roots volatile components and fatty acids were analyzed. The essential oil yield was 0.06% in the control, on the
basis of dry matter weight, and did not changed at low concentration (25 mM), while it increased significantly with increasing
NaCl concentrations to reach 0.12 and 0.21% at 50 and 75 mM NaCl, respectively. The major volatile component was (E)-2-dodecenal with 52% of total essential oil constituents, followed by decanal, dodecanal, (E)-2-tridecenal and (E)-2-dodecenal. Further, the amount of these compounds was affected differently by the NaCl level. Total fatty acid amount
of coriander roots increased significantly only with 50 and 75 mM NaCl. Three major fatty acids: linoleic (43%), oleic (25.5%)
and palmitic (21.6%) were identified. Linoleic acid amount remains unchanged at 25 mM, while it increased with raising NaCl
concentrations. However, oleic acid amount decreased only at 25 mM and no effect was observed at 50 and 75 mM. Fatty acid
percentages were differently affected by salt. The oleic/linoleic ratio was reduced with raising NaCl concentrations. 相似文献
8.
da Silveira LT Junta CM Monesi N de Oliveira-Pelegrin GR Passos GA Rocha MJ 《Cellular and molecular neurobiology》2007,27(5):575-584
Summary 1. This study presents a time course analysis of the messenger RNA (mRNA) levels of c-fos, vasopressin (VP), and oxytocin (OT) in the paraventricular (PVN) and supraoptic nucleus (SON), following acute and chronic dehydration by water deprivation.
2. Male Wistar rats were separated into five groups: nondehydrated (control group) and dehydrated for 6, 24, 48 and 72 h. Following water
deprivation, animals were decapitated, their blood was collected for hematocrit, osmolality, and plasma sodium measurements,
and brains were removed for dissection of both PVN and SON.
3. As expected, the hematocrit, osmolality, plasma sodium, and weight loss were increased after water deprivation. In SON,
a significant increase in both VP and OT mRNA expression was observed 6 h after dehydration reaching a peak at 24 h and returning to basal levels of expression at
72 h. In the PVN, an increase in both VP and OT mRNA expression occurred 24 h after dehydration. At 72 h the VP and OT mRNA expression levels had decreased but they were still at higher levels than those detected in control animals.
4. These results suggest that SON is the first nucleus to respond to the dehydration stimulus. Additionally, we also observed
an increase in c-fos mRNA expression in both PVN and SON 6 h after water deprivation, which progressively decreased 24, 48, and 72 h after the
onset of water deprivation. Therefore, it is possible that c-fos may be involved in the modulation of VP and OT genes, regulating the mRNA expression levels on a temporally distinct basis within the PVN and SON. 相似文献
9.
Nitraria retusa and Atriplex halimus (xero-halophytes) plants were grown in the range 0–800 mM NaCl while Medicago arborea (glycophyte) in 0–300 mM NaCl. Plants were harvested after 120 days of salt-treatment. The present study was designed to
study the effect of salinity on root, stem and leaf anatomy, water relationship, and plant growth in greenhouse conditions.
Salinity induced anatomical changes in the roots, stems and leaves. The cuticle and epidermis of N. retusa and A. halimus stems were unaffected by salinity. However, root anatomical parameters (root cross section area, cortex thickness and stele
to root area ratio), and stem anatomical parameters (stem cross section area and cortex area) were promoted at 100–200 mM
NaCl. Indicating that low to moderate salinity had a stimulating effect on root and stem growth of these xero-halophytic species.
At higher salinities, root and stem structures were altered significantly, and their percentages of reduction were higher
in A. halimus than in N. retusa whereas, in M. arborea, they were strongly altered as salinity rose. NaCl (100–300 mM) reduced leaf water content by 21.2–56.2% and specific leaf
area by 51–88.1%, while increased leaf anatomical parameters in M. arborea (e.g. increased thickness of upper and lower epidermis, palisade and spongy mesophyll, entire lamina, and increased palisade
to spongy mesophyll ratio). Similar results were evidenced in A. halimus leaves with salinity exceeding 100 mM NaCl. Leaves of N. retusa were thinner in salt-stressed plants while epidermis thickness and water content was unaffected by salinity. The size of
xylem vessel was unchanged under salinity in the leaf’s main vein of the three species while we have increased number in M. arborea leaf main vein in the range of 200–300 mM NaCl. A longer distance between leaf vascular bundle, a reduced size and increased
number of xylem vessel especially in stem than in root vascular system was evidenced in M. arborea treated plants and only at (400–800 mM) in the xero-halophytic species. The effects of NaCl toxicity on leaf, stem and root
ultrastructure are discussed in relation to the degree of salt resistance of these three species. Our results suggest that
both N. retusa and A. halimus show high tolerance to salinity while M. arborea was considered as a salt tolerant species. 相似文献
10.
11.
Amal Fadl Abdelkader Henrik Aronsson Christer Sundqvist 《Acta Physiologiae Plantarum》2010,32(5):971-978
To examine the effects of salt stress on dark-grown wheat (Triticum aestivum), seedlings of the salt-tolerant cultivar Sids 1 and the susceptible cultivar Giza 168 were grown in darkness for 14 days
in nutrient solution with and without 200 mM of supplementary salt (100 mM of NaCl and 100 mM of KCl). During this time, we
monitored their protochlorophyllide (Pchlide) contents, ratios of photoactive to non-photoactive forms of Pchlide (from 655/633-nm
emission ratios in their 77 K fluorescence emission spectra) and (following flash irradiation) ratios of newly formed chlorophyllide
(Chlide) to non-photoactive Pchlide. In addition, the accumulation of chlorophyll a in leaf sections was monitored during prolonged (24 h) irradiation. The results depended on the developmental state of the
seedlings. However, the salt stress treatment caused marked increases in both Pchlide contents in dark-grown leaves and in
Chlide contents following irradiation of leaf sections of both cultivars. The ratio of phototransformable to non-phototransformable
Pchlide and the abundance of newly formed Chlide were also increased by the salt stress. Further, leaves of salt-stressed
seedlings consistently accumulated more chlorophyll a than leaves of unstressed seedlings when floating on the nutrient solution (with or without supplementary salt) in continuous
white light. The findings are consistent with the hypothesis that increased levels of the long-wavelength form of Pchlide
contribute to protective mechanisms against salt stress. 相似文献
12.
Mark R. Wilkins Lilis Suryawati Niels O. Maness Donna Chrz 《World journal of microbiology & biotechnology》2007,23(8):1161-1168
Summary Two ethanologenic yeasts, Saccharomyces cerevisiae and Kluyveromyces marxianus, were used to ferment sugar solutions modeling hydrolyzed Valencia orange peel waste at 37°C. Orange stripper oil produced
from orange peel was added in various amounts to determine its effect on ethanol production. The minimum peel oil concentration
that inhibited ethanol production was determined after 24, 48 and 72 h and the two yeasts were compared to one another in
terms of ethanol yield. Minimum inhibitory peel oil concentrations for ethanol production were 0.05% at 24 h, 0.10% at 48 h,
and 0.15% at 72 h for both yeasts. S. cerevisiae produced more ethanol than K. marxianus at each time point. 相似文献
13.
Of 23 strains of halotolerant (up to 12% w/v NaCl) photosynthetic bacteria isolated from various sources, one isolate, SH5,
accumulated intracellular 5-aminolevulinic acid (ALA) at 0.45 μg/g dry cell wt (DCW) growing aerobically in the dark. The
strain was identified as Rhodobacter sphaeroides using 16S rDNA sequencing. Biosynthesis of ALA was enhanced to 14 μg/g DCW using modified glutamate/glucose (50 mM) medium
with the addition of 10 mM levulinic acid after 24 h cultivation. Addition of 30 μM Fe2+ to this medium increased the yield to 226 μg/g DCW. 相似文献
14.
Kexue Li Youning Wang Chunyu Han Wensheng Zhang Huizhen Jia Xia Li 《Plant Growth Regulation》2007,53(3):195-206
Flowering timing is very important for the reproductive success of higher plants. However, effects of salt on plant flowering
and the underlying molecular mechanisms are largely unknown. Here, we show that salt stress delays flowering in Arabidopsis in a dose-dependent manner. Mild salt stress (≤50 mM NaCl) promoted and prolonged the vegetative growth, whereas high salinity
(≥100 mM NaCl) largely delayed or inhibited the transition from vegetative growth to reproductive development. The gibberellin
(GA)-pathway plays an important role in this phenotype, and application of exogenous GA could restore late flowering induced
by salt. In addition, the CONSTANS (CO)/FLOWERING LOCUS T (FT) module may also play a critical role in mediating the effects of salt on flowering. The mRNA abundance of CO was significantly reduced by salt stress in a dose-dependent manner. The constans (co-2) mutants did not respond to moderate salt stress, whereas over-expressing CO manifested no delay in flowering time in response to salinity. Expression of FT, SOC1 and LFY in the downstream of the pathways was also reduced by salt according to dose. Moreover, salt-sensitive mutant salt overly sensitive3 (sos3) exhibited greater sensitivity in flowering, further suggesting that ion disequilibrium mediates salt-induced late flowering.
Kexue Li and Youning Wang contributed equally to this report. 相似文献
15.
Péter Bartos Margit Balázs István Kiss Zoltán Bihari Olga Kelemen Imre Mécs 《World journal of microbiology & biotechnology》2008,24(6):875-878
The toxic and growth inhibiting effects of methyl tert-butyl ether (MTBE) on the hydrocarbon-degrading Pseudomonas veronii T1/1 strain (isolated from gasoline contaminated soil) were studied. In our experiments, the MIC of MTBE was found to be
60 mM and the EC50 was 51.7 mM. In the concentration range 0–30 mM, MTBE did not significantly influence the growth parameters of this bacterium,
but at concentrations over 30 mM MTBE exerted a significant growth inhibiting effect. In the presence of 70 mM MTBE, the specific
growth rate dropped from 0.4731 to 0.1201 h−1, while the length of the lag period increased from 5.41 to 17.01 h and the yield coefficient declined from 0.2652 to 0.0718 g g−1. MTBE at 100 mM inhibited the growth of this strain completely. These findings may have important environmental implications,
as high concentrations of MTBE could influence the efficiency of soil and groundwater bioremediation processes significantly. 相似文献
16.
Xylanase A of Thermotoga neapolitana contains binding domains both at the N- and C-terminal ends of the catalytic domain. In the N-terminal position it contains
two carbohydrate-binding modules (CBM) which belong to family 22. These CBMs bind xylan but not to cellulose. The gene encoding
the mature peptide of these CBMs was fused with an alkaline active GH10 xylanase from Bacillus halodurans S7 and expressed in Escherichia coli. The (His)6 tagged hybrid protein was purified by immobilized metal affinity chromatography and characterized. Xylan binding by the chimeric
protein was influenced by NaCl concentration and pH of the binding medium. Binding increased with increasing salt concentration
up to 200 mM. Higher extent of binding was observed under acidic conditions. The fusion of the CBM structures enhanced the
hydrolytic efficiency of the xylanase against insoluble xylan, but decreased the stability of the enzyme. The optimum temperature
and pH for the activity of the xylanase did not change. 相似文献
17.
HuiPing Mao Fumiko Iwanaga Norikazu Yamanaka Fukuju Yamamoto 《Landscape and Ecological Engineering》2008,4(2):75-82
Growth, photosynthesis, and Na+, K+, and Ca2+ distributions were investigated in 2-year-old hydroponically cultured Populus alba L. cuttings exposed to salt stresses (0, 0.85, 8.5, 17, and 85 mM NaCl in experiment 1 and 0, 50, 100, 150, and 200 mM in
experiment 2) for 4 weeks in 2/5 Hoagland solution. Salt did not markedly inhibit height growth and diameter increment in
150 and 100 mM NaCl, respectively. The 85 mM NaCl treatment increased the dry weights of roots and total dry weight of plants,
while 150 mM NaCl significantly reduced the dry weights of leaves, stems, and total plant weight. The decline in the photosynthetic
rate lagged 2 weeks behind that of stomatal conductance in the 50 and 100 mM salt solutions. Different ions exhibited different
distributions in different parts of the plant. Most Na+ ions were excluded and/or compartmentalized in roots at low and moderate salt stress (≤50 mM). K+ content in leaves increased with the increase in the salt concentration in the growth solutions. 相似文献
18.
Fawzeia H. Elmhalli Katinka Pålsson Jan Örberg Thomas G. T. Jaenson 《Experimental & applied acarology》2009,48(3):251-262
The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A–E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs
at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate
increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results
obtained by methods A, C and E, the LC50 range was 0.035–0.037 mg PMD/cm2 and the LC95 range was 0.095–0.097 mg PMD/cm2 at 4 h of exposure; the LT50 range was 2.1–2.8 h and the LT95 range was 3.9–4.2 h at 0.1 mg PMD/cm2. To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm2) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed
that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic
to nymphs of I. ricinus and may be useful for tick control. 相似文献
19.
Sushma Tamta Lok Man S. Palni Vijay K. Purohit Shyamal K. Nandi 《In vitro cellular & developmental biology. Plant》2008,44(2):136-141
An efficient and reproducible method for the regeneration of multiple shoots of brown oak (Quercus semecarpifolia Sm.) has been developed in which a part of the petiolar tube containing a primary shoot is used as the explant. Explants
derived from in vitro grown seedlings were cultured either on Murashige and Skoog or Woody Plant medium (WPM) containing different concentrations
of benzyladenine (BAP) throughout the range of 1–20 μM. WPM supplemented with 20 μM BAP was found to be best for adventitious
shoot induction and for the multiplication of individual shoots. In-vitro-produced shoots were rooted using a two-step method. Firstly, shoots were cultured on WPM containing indolebutyric acid (IBA)
at either 50 or 100 μM for 24 or 48 h. Secondly, the shoots were transferred to plant-growth-regulator-free half-strength
WPM. The second step not only considerably improved the rooting percentage but also minimized the formation of basal callus.
The most effective first-step treatment was found to be 100 μM IBA for 24 h, which initiated rooting at a frequency of 100%.
Well-rooted plants were transferred to plastic cups containing nonsterile, sieved soil and farmyard manure, hardened under
greenhouse conditions, and then successfully established in pots. This procedure is suitable for use in large-scale production
of plants and may have potential application in additional oak species. 相似文献
20.
Photosynthesis and photosystem 2 efficiency of two salt-adapted halophytic seashore <Emphasis Type="Italic">Cakile maritima</Emphasis> ecotypes 总被引:1,自引:1,他引:0
W. Megdiche K. Hessini F. Gharbi C. A. Jaleel R. Ksouri C. Abdelly 《Photosynthetica》2008,46(3):410-419
The effects of salinity (0–400 mM NaCl, marked S0, S100, S200, and S400) on growth, photosynthesis, photosystem 2 (PS2) efficiency, ion relations, and pigment contents were studied in two seashore
Cakile maritima ecotypes (Tabarka and Jerba, respectively, sampled from humid and arid bioclimatic areas). Growth of Jerba plants was improved
at S100 as compared to S0. Tabarka growth was inhibited by salinity at all NaCl concentrations. Leaf sodium and chloride concentrations increased with
medium salinity and were higher in Jerba than in Tabarka plants. Chlorophyll content, net photosynthetic rate, stomatal conductance
(g
s), and intracellular CO2 concentration were stimulated at moderate salinity (S100) in Jerba plants and inhibited at higher salt concentrations in both ecotypes: g
s was the most reduced parameter. The maximum quantum efficiency of PS2 (Fv/Fm), quantum yield, linear electron transport rate, and efficiency of excitation energy capture by open PS2 reaction centres
showed no significant changes with increasing salt concentration in Jerba plant and were decreased in Tabarka subjected to
S400. However, the efficiency of dissipation of excess photon energy in the PS2 antenna was maintained in Jerba and was increased
in Tabarka plants challenged with S400. Hence the relative salt tolerance of Jerba was associated with a better ability to use Na+ and Cl− for osmotic adjustment, the absence of pigment degradation, and the concomitant PS2 protection from photodamage. 相似文献