共查询到20条相似文献,搜索用时 15 毫秒
1.
Lydia Beuck Agostina Vertino Elizaveta Stepina Marek Karolczak Olaf Pfannkuche 《Facies》2007,53(2):157-176
The skeleton morphology of the azooxanthellate cold-water coral Lophelia pertusa can be strongly influenced by invasive boring sponges that infest corallites in the still living part of the colony. Atypically
swollen corallites of live Lophelia pertusa from the Galway Mound (Belgica Carbonate Mound Province, Porcupine Seabight, NE Atlantic), heavily excavated by boring organisms,
have been examined with a wide range of non-destructive and destructive methods: micro-computed tomography, macro- and microscopic
observations of the outer coral skeleton, longitudinal and transversal thin sections and SEM analyses of coral skeleton casts.
As a result, three excavating sponge species have been distinguished within the coral skeleton: Alectona millari, Spiroxya heteroclita and Aka infesta. Furthermore, four main coral/sponge growth stages have been recognised: (1) cylindrical juvenile corallite/no sponge cavities;
(2) flared juvenile corallite/linear sponge cavities (if present); (3) slightly swollen adult corallites/chambered oval sponge
cavities; (4) very swollen adult corallites/widespread cavities. The inferred correlation between corallite morphology and
boring sponge infestation has been detected in micro-computed tomography (micro-CT) images and confirmed in sponge trace casts
and peculiar features of coral skeleton microstructure.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users. 相似文献
2.
Brück TB Brück WM Santiago-Vázquez LZ McCarthy PJ Kerr RG 《Marine biotechnology (New York, N.Y.)》2007,9(5):561-576
This study examined the microbiota associated with the marine azooxanthellate octocorals Leptogorgia minimata, Swiftia exertia, and Iciligorgia schrammi collected from moderate depths (45 m). Traditional aerobic plate culture, fluorescence in situ hybridization (FISH), and
molecular identification of the 16S rDNA region were used for this purpose. In general, cultures were found to be selective
for Gammaproteobacteria, Alphaproteobacteria, and Firmicutes. Interestingly, FISH counts for Firmicutes in the whole coral
(holobiont) were near the detection limit of this assay, representing less than 6% of the total detectable microbiota in all
counts. Proteobacteria, especially Alpha- and Gammaproteobacteria, made up the majority of the total microbiota in the holobionts.
In addition, the absence of zooxanthellae in these three corals was confirmed by the use of polymerase chain reaction (PCR)
and dinoflagellate-specific primers, and spectrophotometric chlorophyll pigment measurements. No evidence of zooxanthellae
could be found in any of the corals by either of these techniques. This is the first study examining the microbiota marine
octocorals, which grow at moderate depth (40 to 100 m) in the absence of direct sunlight.
Thomas B. Brück and Wolfram M. Brück have made equal contributions to this publication. 相似文献
3.
Charlotte R. Dromard Yolande Bouchon-Navaro Sébastien Cordonnier Mireille Harmelin-Vivien Claude Bouchon 《Environmental Biology of Fishes》2018,101(3):441-448
Stegastes adustus and Stegastes planifrons are two species of damselfishes commonly found in the Caribbean. These territorial fishes have been widely studied due to their major ecological role on coral reef in controlling the growth of macroalgae that compete with corals for space and, inversely, on their deleterious role in destroying coral tissues to impulse the development of algae. However, few studies were conducted on the biotic and abiotic components of their territories. In the present study, territory size and surfaces of benthic components (macroalgae, algal turf, massive corals, branching corals, Milleporidae, sponges, sand and rubbles) were estimated for the two species at two contrasted sites. At Ilet Pigeon site (IP), the two damselfishes were found at different depth and exhibited different territory sizes. S. adustus defended a larger territory characterized by massive corals, sand and Milleporidae, while S. planifrons territories were smaller, deeper and characterized by branching corals, sponges and rubble. At Passe-à-Colas site (PC), the two fish species coexisted in the same depth range and defended territories of similar size. Their territories presented higher proportions of macroalgae, but smaller surfaces of Milleporidae than at IP. At PC, the main difference between the two species was a higher surface of massive corals inside S. planifrons territories than S. adustus territories. Differences in microhabitat characteristics between the two Stegastes seemed mostly site related. This resulted from the high plasticity of two species, allowing them to persist on Caribbean coral reefs after the decline of most branching acroporids, their former favorite habitats. 相似文献
4.
The anamorphic fungus Sporothrix inflata, known as a soil-borne fungus with worldwide distribution, was isolated for the first time from the cortex and central cylinder
of living and dead roots of healthy and diseased oak trees (Quercus robur and Q. petraea). Isolation frequencies of S. inflata from oak roots varied according to the health status of trees, oak species, study sites, soil depth and root diameter. Colony
morphology and growth rate of isolates are influenced by colony age and type of culture medium. 相似文献
5.
The branching scleractinian coral Agaricia tenuifolia is abundant on reefs in Belize, over an exceptionally broad range of depth, flow regime, and irradiance. Photosynthesis and respiration of coral branches were measured over a range of irradiance and unidirectional flow speeds (1–10 cm s–1) using a small-volume respirometry chamber designed for flat coral branches. Respiration rate increased significantly with flow speed; however, there was no significant effect of flow on either α or Pmax, indicating that this coral could thus carry out maximum photosynthesis even at very low flow. This result contrasts with published results for other coral species that experience a significant increase in net photosynthesis with flow speed. Growth rates of A. tenuifolia were measured using branch fragments in a variety of reef habitats, over a range of water flow speeds. Growth rates were comparable over most habitat types, across a depth range of 1–15 m. Compared to 1 m, flow and irradiance at 15 m decreased to less than 20% and less than 50%, respectively. Reduced growth was observed only at 24-m depth, and in low-flow microhabitats (concavities) at 15 m. Transplants to 1 m, in the surf zone, also had reduced growth and were the only group to suffer significant colony mortality. At 8- and 15-m depth, growth rate of flat coral branches was not affected by orientation (parallel or perpendicular to flow) or shading. Compared with studies of other species, A. tenuifolia displays an ability to utilize a greater range of habitats and flow speeds, suggesting that it may have specific adaptations that allow it to tolerate very low flow conditions. 相似文献
6.
Laboratory experiments were conducted to elucidate the allelopathic effects of exudates from the aquatic macrophyte Stratiotes aloides on the growth and morphology of the green alga Scenedesmus obliquus. Both water originating from a S. aloides culture and water that had not been in contact with S. aloides was simultaneously inoculated with S. obliquus cells. In all experiments we observed a highly significant inhibitory effect of Stratiotes water on the green alga. The duration of the lag phase as well as the initial biovolume doubling time of S. obliquus were extended. The growth rate of S. obliquus was only significantly inhibited by the younger Stratiotes plants. Furthermore, the mean particle volume (MPV) of Scenedesmus increased significantly in the presence of Stratiotes water in all three experiments. Microscopic analyses confirmed that S. obliquus forms more colonies in the presence of water from a S. aloides culture. Colonies of phytoplankton have higher sinking rates than single phytoplankton cells of the same species and disappear faster from the upper water layers, reducing the competition for light between algae and macrophytes. 相似文献
7.
An experiment was carried out to evaluate the effects of phosphorus concentration (1, 4 and 10 mg l−1) and temperature (15 and 25°C) on chlorophyll a (chl a) contents and cell size/volume of green alga Scenedesmus
obliquus and blue green alga Microcystis aeruginosa. Long-term field data from Lake Taihu, a large, shallow eutrophic lake between Jiangsu and Zhejiang Provinces, China, was
also used to evaluate the effect of temperature on the model between chl a and total phosphorus (TP). The chl a content of both algae increased with an increase in phosphorus concentration and temperature. Temperatures showed a significantly
different effect on chl a content of S. obliquus at a phosphorus concentration of 10 mg l−1, whereas there was no significant difference at the two lower phosphorus levels. For M. aeruginosa, temperatures presented significantly different effects on the chl a contents at three phosphorus concentrations. Chl a content of neither alga presented an interaction between the nutrient and the temperature. Long-term field data from Lake
Taihu also indicated that the addition of temperature to the model increased predictability of chl a by TP. The length/diameter and volume of both algae were greater at the lower temperature and phosphorus concentration. Moderate
negative correlations were observed between algal size, volume, and chl a content. Our results suggest that phosphorus concentration and temperature could change chl a contents and size in species-specific algal cells and that temperature should be considered when building the model of TP
and chl a concentration. 相似文献
8.
Hai-Nan Su Bin-Bin Xie Xiu-Lan Chen Jin-Xia Wang Xi-Ying Zhang Bai-Cheng Zhou Yu-Zhong Zhang 《Journal of applied phycology》2010,22(1):65-70
Allophycocyanin (APC) is a minor component of phycobiliproteins in cyanobacteria and red algae. This paper describes a simple
and inexpensive extracting method for isolating APC from Spirulina (Arthrospira) platensis with high efficiency. The crude phycobiliprotein extract was pretreated by ammonium sulfate fractionation. Then, by adding
hydroxylapatite into crude phycobiliprotein extract dissolved in 20 mM phosphate buffer (pH 7.0), APC was selectively adsorbed
by hydroxylapatite but C-phycocyanin (C-PC) was not. The hydroxylapatite was collected and APC was extracted from the crude
phycobiliprotein extract. Then, the enriched APC was washed off from the hydroxylapatite using 100 mM phosphate buffer (pH 7.0).
In this simple extracting method it was easy to remove C-PC and isolate APC in large amounts. The absorbance ratio A
650/A
280 of extracted APC reached 2.0. The recovery yield was 70%, representing 4.61 mg · g−1 wet weight. The extracted APC could be further purified by a simple anion-exchange chromatography with a pH gradient from
5.6 to 4.0. The absorbance ratio A
650/A
280 of the purified APC reached 5.0, and the overall recovery yield was 43%, representing 2.83 mg · g−1 wet weight. Its purity was confirmed by native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE. 相似文献
9.
Alexandre Alonso Alves Lúcio Mauro da Silva Guimarães Agnaldo Rodrigues de Melo Chaves Fábio Murilo DaMatta Acelino Couto Alfenas 《Acta Physiologiae Plantarum》2011,33(5):1831-1839
One of the most important diseases of eucalyptus plantations is caused by the rust fungus Puccinia psidii. While the genetic basis of rust resistance has been addressed recently, little is known about the physiological aspects
of Eucalyptus–P. psidii interaction. In order to fill this gap, we undertook a study investigating the effects of P. psidii infection on photosynthetic processes of two E. urophylla clones with contrasting resistance to the pathogen. Our results show that gas exchange and chlorophyll a fluorescence parameters were virtually unaffected in the resistant clone. In the susceptible clone, photosynthetic rates
were chiefly constrained by biochemical limitations to carbon fixation. Photosynthesis was impaired only in symptomatic tissues
since the reductions in photosynthetic rates were proportional to the diseased leaf area. Rust infection provoked chronic
photoinhibition to photosynthesis in the susceptible clone. Overall, differences in the ability for light capture, use and
dissipation may play a significant role in explaining the clonal differences in Eucalyptus in response to P. psidii infection. To our knowledge, this is the first report of the effect of rust infection on gas exchange and chlorophyll a fluorescence parameters in Eucalyptus. 相似文献
10.
This study describes two phenotypes of Arabidopsis thaliana (ecotype Columbia) developed in vitro under salt stress (75 mM NaCl). The phenotypes 01 and 02 appeared visibly distinguishable by rosette morphology and competence
to produce flowers. Phenotype 01, sensible to salt stress, accumulated high quantities of Na+, showed a slight reduction in dry mass, and high protein and chlorophyll contents. Moreover, its anatomy exhibited some xeromorphic
traits. Phenotype 02, clearly salt tolerant, showed a morphology similar to control plants, displaying typical phyllotactic
rosette and flowering stalk production. Accumulation of Na+, protein and chlorophyll contents were close to control plants. Reversion experiments on NaCl free MS medium, showed a partially
recovered phenotype 01. A threshold salt stress concentration that permits the simultaneous development of two phenotypes,
was found. 相似文献
11.
Several chromosome types have been recognized in Citrus and related genera by chromomycin A3 (CMA) banding patterns and fluorescent in situ hybridization (FISH). They can be used to characterize cultivars and species
or as markers in hybridization and backcrossing experiments. In the present work, characterization of six cultivars of P. trifoliata (“Barnes”, “Fawcett”, “Flying Dragon”, “Pomeroy”, “Rubidoux”, “USDA”) and one P. trifoliata × C. limonia hybrid was performed by sequential analyses of CMA banding and FISH using 5S and 45S rDNA as probes. All six cultivars showed
a similar CMA+ banding pattern with the karyotype formula 4B + 8D + 6F. The capital letters indicate chromosomal types: B, a chromosome
with one telomeric and one proximal band; D, with only one telomeric band; F, without bands. In situ hybridization labeling
was also similar among cultivars. Three chromosome pairs displayed a closely linked set of 5S and 45S rDNA sites, two of them
co-located with the proximal band of the B type chromosomes (B/5S-45S) and the third one co-located with the terminal band
of a D pair (D/5S-45S). The B/5S-45S chromosome has never been found in any citrus accessions investigated so far. Therefore,
this B chromosome can be used as a marker to recognize the intergeneric Poncirus × Citrus hybrids. The intergeneric hybrid analyzed here displayed the karyotype formula 4B + 8D + 6F, with two chromosome types B/5S-45S
and two D/5S-45S. The karyotype formula and the presence of two B/5S-45S chromosomes clearly indicate that the plant investigated
is a symmetric hybrid. It also demonstrates the suitability of karyotype analyses to differentiate zygotic embryos or somatic
cell fusions involving trifoliate orange germplasm.
During the submission of this paper, we analyzed 25 other citrus cultivars with the same methodology and we found that the
chromosome marker reported here can indeed distinguish Poncirus trifoliata from grapefruits, pummelos, and one variegated access of Citrus, besides the previously reported access of limes, limons, citrons, and sweet-oranges. However, among 14 mandarin cultivars,
two of them displayed a single B/5S-45S chromosome, whereas in Citrus hystrix D.C., a far related species belonging to the Papeda subgenus, this chromosome type was found in homozygosis. Since these two mandarin cultivars are probably of hybrid origin,
we assume that for almost all commercial cultivars and species of the subgenus Citrus this B type chromosome is a useful genetic marker. 相似文献
12.
The present study on efficacy of different Glomus species, an arbuscular mycorrhizal (AM) fungus (G. aggregatum, G. fasciculatum, G. mosseae, G. intraradices) on various growth parameters such as biomass, macro and micronutrients, chlorophyll, protein, cytokinin and alkaloid content
and phosphatase activity of pink flowered Catharanthus roseus plants showed that all Glomus species except G. intraradices enhanced the chlorophyll, protein, crude alkaloid, phosphorus, sulphur, manganese and copper contents of C. roseus plants along with phosphatase activity significantly over uninoculated plants. However only G. mosseae and G. fasciculatum exhibited superior symbiotic relationship with the plant. G. mosseae was found to be the best for increasing the crude alkaloid content (8.19%) in leaf and also in increasing the quantity of
important alkaloids vincristine and vinblastine. 相似文献
13.
Inspection of two female colonies of the monopodial black coral Cirrhipathes cfr. anguina from the coral reef of the Marine Park of Bunaken (Indonesia) revealed the occurrence of crustacean developing eggs within
the mesenterial filaments of the polyps. Egg diameter, which in the smallest gametes was about 50–60 μm, increased in tandem
with embryo development, reaching the value of 170 μm, at the nauplius stage. The attribution to the crustacean taxon was
derived from morphological investigations carried out in light and electron microscopy (TEM, SEM) on the eggs and on the embryos
removed from them. The final stage of nauplius was characterised by three pairs of appendages: uniramouse antennulae, biramouse
antennae and manidibulae. In addition, naupliar eye and caudal setae were also evident. These nauplii were ascribed to the
larval stage of an unidentified species. Coral/copepod association could represent a reproductive strategy, put into action
by some marine copepods. Incubation within an appropriate host prevents predation by planktotrophic organisms, thus reducing
population depletion. 相似文献
14.
E. N. Voronova I. V. Konyukhov Yu. V. Kazimirko S. I. Pogosyan A. B. Rubin 《Russian Journal of Plant Physiology》2009,56(6):753-760
Two populations of a diatom alga Thallassiosira weisflogii were grown at photon flux densities (PFD) of 0.8 and 8 μmol/(m2 s). For both diatom populations, the recovery of chlorophyll fluorescence parameters (F
0, F
m, F
v/F
m, and NPQ) was monitored after nondestructive irradiation by visible light at PFD of 40 μmol/(m2 s) and after high-intensity irradiation by visible light (1000–4000 μmol/(m2 s)). The exposure of diatoms to PFD of 40 μmol/(m2 s)—higher than PFD used for algal growth but still nondamaging to photosynthetic apparatus—induced nonphotochemical quenching
(NPQ), which was stronger in algae grown at higher PFD (8 μmol/(m2 s)) than in algae grown at low light. After irradiation with high-intensity light, the recovery of chlorophyll fluorescence
parameters was more pronounced in algae grown at elevated PFD level. During short-term irradiation of diatoms with high-intensity
visible light (1000 μmol/(m2 s)), a stronger NPQ was observed in the culture adapted to high irradiance. After the treatment of algae with dithiothreitol
(an inhibitor of carotenoid deepoxidase in the diadinoxanthin cycle) or NH4Cl (an agent abolishing the proton gradient at thylakoid membranes), a short exposure of algae to PFD of 40 μmol/(m2 s) induced hardly any nonphotochemical quenching. The results indicate the dominant contribution of xanthophyll cycle carotenoids
to energy-dependent quenching. 相似文献
15.
The relationship between Sporidiobolus johnsonii and S. salmonicolor was investigated using rDNA sequence data. Two statistically well-supported clades were obtained. One clade included the
type strain of S. johnsonii and the other included the type strain of S. salmonicolor. However, some mating strains of S. salmonicolor were found in the S. johnsonii group. These strains belonged to mating type A2 and were sexually compatible with mating type A1 strains from the S. salmonicolor group. DNA–DNA reassociation values were high within each clade and moderate between the two clades. In the re-investigation
of teliospore germination, we observed that the basidia of S. salmonicolor were two-celled. In S. johnsonii, basidia were not formed and teliospore germination resulted in direct formation of yeast cells. We hypothesize that the
S. johnsonii clade is becoming genetically isolated from the S. salmonicolor group and that a speciation process is presently going on. We suspect that the observed sexual compatibility between strains
of the S. johnsonii and S. salmonicolor groups and the possible genetic flow between the two species has little biological relevance because distinct phenotypes
have been fixed in the two taxa and intermediate (hybrid) sequences for LSU and ITS rDNAs have not been detected.
An erratum to this article can be found at 相似文献
16.
Allelopathic effects of the submerged macrophyte Potamogeton malaianus on Scenedesmus obliquus were assessed using a two-phase approach under controlled laboratory conditions. In the co-culture experiment (phase І),
the growth of S. obliquus at two different initial cell densities was significantly inhibited by P. malaianus. Moreover, the growth inhibition was dependent on the biomass density of P. malaianus. Antioxidant enzymes (SOD, CAT and POD), MDA, APA, total soluble protein, protein electrophoretic pattern and morphology
of S. obliquus were determined after the co-culture experiment was terminated. The activities of SOD, CAT, POD and APA at the low initial
cell density were stimulated, the contents of MDA and total soluble protein were increased, and some special protein bands
disappeared in P. malaianus treatments. The macrophyte had no effect on the activities of SOD and APA at the high initial cell density, but significantly
influenced other physiological parameters of S. obliquus with the increase of biomass density. The morphology of S. obliquus showed no difference in the macrophyte treatments and the controls, and the cultures were dominated by 4-celled coenobia.
The results indicated P. malaianus had significant allelopathic effects on the growth and physiological processes of S. obliquus. Moreover, the allelopathic effects depended on initial algal cell density, biomass density of the macrophyte, and their
interaction. In the experiment of P. malaianus culture filtrates (phase II), filtrates from combined culture of plant and S. obliquus at the low initial cell density exhibited no apparent growth inhibitory effect on S. obliquus. The result showed that initial addition of growth-inhibiting plant filtrates had no allelopathic effect on S. obliquus. We concluded that the allelopathic effects on S. obliquus were found in the presence of P. malaianus, but not in P. malaianus filtrates. However, the absence of allelopathic effect on S. obliquus might be due to the very low concentrations of allelochemicals in the filtrates.
Handling editor: S. M. Thomas 相似文献
17.
In the present work, the long-term effect (14 days) of copper on the levels of intracellular and total copper accumulation,
growth, assimilation pigment composition, chlorophyll a fluorescence, soluble protein content and oxidative status (production of hydrogen peroxide and superoxide) in two algal
species (Scenedesmus quadricauda and Trebouxia erici) was assessed. Scenedesmus quadricauda is a free-living alga while Trebouxia erici is the photobiont of a lichen. The presence of copper negatively affected growth, assimilation pigments, chlorophyll a fluorescence, soluble protein content and oxidative status in both the algae. However, Scenedesmus was much more sensitive compared to Trebouxia. 相似文献
18.
Jesús M. Castillo Enrique Mateos-Naranjo Francisco J. Nieva Enrique Figueroa 《Hydrobiologia》2008,614(1):363-371
The South American cordgrass Spartina densiflora is invading European salt marshes getting into contact with the indigenous and endangered low-marsh dominant, Spartina maritima. This work describes the evolution of the plant zonation during 7 years in a marsh of S. maritima invaded by S. densiflora. S. maritima appeared throughout the whole intertidal gradient from 1.72 to 3.33 m over Spanish Hydrographic Zero (SHZ), showing its higher
biomasses and shoot densities at low elevations. In contrast, S. densiflora only invaded upper areas (>+2.59 m SHZ) at the centre of circular tussocks of S. maritima. Above-ground biomass of S. maritima dropped drastically at maximum occupation of space by the alien, and its shoot density and above-ground biomass decreased
at S. densiflora zone during the study. The competitive potential of S. densiflora was reflected in high above- and below-ground biomass and shoot densities, accompanied by elevated wrack accumulation and
the absence of other marsh plants presented together with S. maritima from areas dominated by S. densiflora. S. densiflora altered the native vegetational zonation pattern through the invasion of the centre of S. maritima tussocks; however, the alien invasion may be limited by the presence of the autochthonous cordgrass at lower elevations.
Handling editor: Luis Mauricio Bini 相似文献
19.
Conde-Álvarez RM Bañares-España E Nieto-Caldera JM Flores-Moya A Figueroa FL 《Oecologia》2011,166(4):853-862
We have studied the plasticity of the photosynthetic apparatus in the endangered aquatic macrophyte Althenia orientalis to the gradient of light availability within its meadow canopy. We determined diurnal change in situ irradiance, light quality,
in vivo chlorophyll a fluorescence, ex situ oxygen evolution rates, respiration rate and pigment concentration. The levels of photosynthetic photon
flux density (PFD) and ultraviolet radiation (UVR) and the red/far-red ratio decreased with depth within the canopies of A. orientalis. Apical leaves had a greater decrease of the maximal quantum yield (F
v/F
m) in the morning and a faster recovery rate in the afternoon than those in the basal ones. The relative electron transport
rate (ETRr) was not saturated at any time of the day, even in the apical leaves that received the highest light. The maximum
light-saturated rate of gross photosynthesis (GPmax) took place in apical leaves around noon. The chlorophyll a/b ratio values were higher, and the chlorophyll/carotenoid ratio values lower, in apical leaves than basal ones. The highest
concentrations in total carotenoids were reached in the apical leaves around noon. A. orientalis has a high capacity to acclimatize to the changes in the light environment, both in quality and quantity, presenting sun
and shade leaves in the same stem through the vertical gradient in the canopy. 相似文献
20.
J. Rodríguez-Calcerrada J. A. Pardos L. Gil I. Aranda 《Trees - Structure and Function》2007,21(1):45-54
Photosynthetic acclimation of two co-occurring deciduous oaks (Quercus petraea and Quercus pyrenaica) to a natural light gradient was studied during one growing season. In the spring of 2003, 90 seedlings per species were
planted along a transect resulting from a dense Pinus sylvestris stand, an adjacent thinned area and a 10-m-wide firebreak (16.5–60.9% Global Site Factor (GSF)). In two dates of the following
summer, we measured leaf gas exchange, carboxylation efficiency (CE), chlorophyll and nitrogen content, light–response curves
of chlorophyll a fluorescence parameters, and leaf mass per area (LMA). Summer was mild, as evidenced by leaf predawn water potential (Ψpd), which reduced the interactive effect of water stress on the response of seedlings to light. Q. pyrenaica had higher LMA, CE, stomatal conductance (g
s max) and photosynthesis per unit area than Q. petraea at all growth irradiances. , LMA, g
s max and electron transport rate (ETR) all increased with light availability (GSF) in a similar fashion in both species. Light
had also a clear effect on the organization of Photosystem II (PS II), as deduced by chlorophyll a fluorescence curves. Chlorophyll concentration (Chlm) decreased with increasing light availability in Q. pyrenaica but it did not in Q. petraea. Seedlings of Q. petraea acclimated to higher irradiances showed a greater non-photochemical quenching (NPQ) than those of Q. pyrenaica. This suggests a higher susceptibility to high light in Q. petraea, which would be consistent with a better adaptation to shade, inferred from the lower LMA or the lower rate of photosynthesis. 相似文献