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1.
Photosynthesis and growth rates of Laurencia brongniartii J. Agardh (Rhodophyta, Ceramiales) in preparation for cultivation 总被引:2,自引:1,他引:1
Laurencia brongniartii is usually found at depths below 4 m, but can be found in shallow subtidal areas in crevices and on the walls of a coral reef in Amami Oshima Island, Kagoshima Prefecture, Japan, where irradiances were significantly lower than those at similar depths in open water. In preparation for the possible cultivation of this species for its antibiotic compounds, the effects of temperature and irradiance on photosynthesis and growth were measured. Photosynthesis and growth rates of L. brongniartii explants were highest at 26 and 28 °C, which closely corresponded to temperatures found during August to late December when it was most abundant. The estimated maximum photosynthesis rate (P
max) was 4.41 mol photon m–2 s–1 at 26 °C and 4.07 mol photon m–2 s–1 at 28 °C. Saturating irradiance occurred at 95 mol photon m–2 s–1 at 26 °C and 65 mol photon m–2 s–1 at 28 °C. In contrast, growth experiments at 41.7 mol photon m–2 s–1 caused bleaching of explants and the maximum growth rate observed during the study was 3.02 ± 0.75% day–1 at 28 °C and 25 mol photon m–2 s–1. The difference in the saturating irradiance for photosynthesis and the irradiance that caused bleaching in growth experiments suggests that long-term exposure to high irradiance was detrimental and should be addressed before the initiation of large scale cultivation. 相似文献
2.
A method of measuring CO2gas exchange (caused, for example, by microalgal photosynthesis on emersed tidal mudflats) using open flow IR gas analyzers is described. The analyzers are integrated in a conventional portable photosynthesis system (LI-6400, LI-COR, Nebraska, USA), which allows manipulation and automatic recording of environmental parameters at the field site. Special bottomless measuring chambers are placed directly on the surface sediment. Measurements are performed under natural light conditions and ambient CO2concentrations, as well as under different CO2concentrations in air, and various PAR radiation levels produced by a LED light source built into one of the measurement chambers. First results from tidal channel banks in a north Brazilian mangrove system at Bragança (Pará, Brazil) under controlled conditions show a marked response of CO2assimilation to CO2concentration and to irradiance. Photosynthesis at 100molmol–1CO2in air in one sample of a well-developed algal mat was saturated at 309mol photons m–2s–1, but increased with increasing ambient CO2concentrations (350 and 1000mol mol–1CO2) in the measuring chamber. Net CO2assimilation was 0.8mol CO2m–2s–1at 100mol mol–1CO2, 5.9mol CO2m–2s–1at 350mol mol–1CO2and 9.8mol CO2m–2s–1at 1000mol mol–1CO2. Compensation irradiance decreased and apparent photon yield increased with ambient CO2concentration. Measurements under natural conditions resulted in a quick response of CO2exchange rates when light conditions changed. We recommend the measuring system for rapid estimations of benthic primary production and as a valuable field research tool in connection with certain ecophysiological aspects under changing environmental conditions. 相似文献
3.
Effect of irradiance, temperature and salinity on growth and toxin production by Nodularia spumigena
The object of this work was to determine, using a full-factorial experiment, the influence of temperature, irradiance and salinity on growth and hepatotoxin production by Nodularia spumigena, isolated from Lake Alexandrina in the south-east of South Australia. Higher levels of biomass (determined as particulate organic carbon, POC), toxin production and intracellular toxin concentration per mg POC were produced under light limited conditions (30 mol m–2 s–1) and at salinities equal to or greater than those experienced in Lake Alexandrina. Both highest biomass and total toxin production rates were recorded at temperatures equal to or greater than those of the lake (20 and 30°C). The temperature at which maximum biomass and toxin production was recorded decreased from 30°C for cultures grown at 30 mol m–2 s–1 to 20°C when grown at 80 mol m–2 s–1. In contrast, intracellular toxin per mg POC was highest at the lowest growth temperature, 10°C, at both 30 and 80 mol m–2 s–1. It appears that the optimum temperature for biosynthetic pathways used in the production of toxin is lower than the optimum temperature for those pathways associated with growth. Intracellular toxin levels were higher in cells cultured at 10°C/30 mol m–2 s–1 whereas the majority of the toxin was extracellular in cells grown at 30°C/30 mol m–2 s–1. This implies that the highest concentration of toxin in lake water would occur under high temperature and high irradiance conditions. Individual environmental parameters of salinity, irradiance and temperature were all shown to influence growth and toxin production. Notwithstanding, the overall influence of these three parameters on toxin production was mediated through their effect upon growth rate. 相似文献
4.
M. Lauerer D. Saftic W. P. Quick C. Labate K. Fichtner E. -D. Schulze S. R. Rodermel L. Bogorad M. Stitt 《Planta》1993,190(3):332-345
Tobacco (Nicotiana tabacum L.) plants transformed with antisense rbcS to decrease the expression of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) have been used to investigate the contribution of Rubisco to the control of photosynthesis in plants growing at different irradiances. Tobacco plants were grown in controlled-climate chambers under ambient CO2 at 20°C at 100, 300 and 750 mol·m–2·s–1 irradiance, and at 28°C at 100, 300 and 1000 mol·m–2·s–1 irradiance. (i) Measurement of photosynthesis under ambient conditions showed that the flux control coefficient of Rubisco (C
infRubisco
supA
) was very low (0.01–0.03) at low growth irradiance, and still fairly low (0.24–0.27) at higher irradiance. (ii) Short-term changes in the irradiance used to measure photosynthesis showed that C
infRubisco
supA
increases as incident irradiance rises, (iii) When low-light (100 mol·m–2·s–1)-grown plants are exposed to high (750–1000 mol·m–2·s–1) irradiance, Rubisco is almost totally limiting for photosynthesis in wild types. However, when high-light-grown leaves (750–1000 mol·m–2·s–1) are suddenly exposed to high and saturating irradiance (1500–2000 mol·m–2·s–1), C
infRubisco
supA
remained relatively low (0.23–0.33), showing that in saturating light Rubisco only exerts partial control over the light-saturated rate of photosynthesis in sun leaves; apparently additional factors are co-limiting photosynthetic performance, (iv) Growth of plants at high irradiance led to a small decrease in the percentage of total protein found in the insoluble (thylakoid fraction), and a decrease of chlorophyll, relative to protein or structural leaf dry weight. As a consequence of this change, high-irradiance-grown leaves illuminated at growth irradiance avoided an inbalance between the light reactions and Rubisco; this was shown by the low value of C
infRubisco
supA
(see above) and by measurements showing that non-photochemical quenching was low, photochemical quenching high, and NADP-malate dehydrogenase activation was low at the growth irradiance. In contrast, when a leaf adapted to low irradiance was illuminated at a higher irradiance, Rubisco exerted more control, non-photochemical quenching was higher, photochemical quenching was lower, and NADP-malate dehydrogenase activation was higher than in a leaf which had grown at that irradiance. We conclude that changes in leaf composition allow the leaf to avoid a one-sided limitation by Rubisco and, hence, overexcitation and overreduction of the thylakoids in high-irradiance growth conditions, (v) Antisense plants with less Rubisco contained a higher content of insoluble (thylakoid) protein and chlorophyll, compared to total protein or structural leaf dry weight. They also showed a higher rate of photosynthesis than the wild type, when measured at an irradiance below that at which the plant had grown. We propose that N-allocation in low light is not optimal in tobacco and that genetic manipulation to decrease Rubisco may, in some circumstances, increase photosynthetic performance in low light.Abbreviations A
rate of photosynthesis
- C
infRubisco
supA
flux control coefficient of Rubisco for photosynthesis
- ci
internal CO2 concentration
- qE
energy-dependent quenching of chlorophyll fluorescense
- qQ
photochemical quenching of chlorophyll fluorescence
- NADP-MDH
NADP-dependent malate dehydrogenase
- Rubisco
ribulose-1,5-bisphosphate carboxylase-oxygenase
- RuBP
ribulose-1,5-bisphosphate
This work was supported by the Deutsche Forschungsgemeinschaft (SFB 137). 相似文献
5.
C. Wiencke 《Polar Biology》1990,10(8):589-600
Summary The seasonal development of the endemic Antarctic Desmarestiales Himantothallus grandifolius, Phaeurus antarcticus, Desmarestia anceps, of a ligulate Desmarestia sp., of the Antarctic cold-temperate Adenocystis utricularis (Dictyosiphonales) and of the endemic Antarctic Ascoseira mirabilis (Ascoseirales) was monitored in a 2-year culture study under fluctuating daylengths mimicking the daylength conditions on King George Island (Antarctica). Temperature was kept constant at 0° C and nutrient levels were maintained at 0.6 moles m–3 nitrate and 0.025 moles m –3 phosphate. Sporophytes were initiated between (April-) June and July in all Desmarestiales. This event was controlled either by induction of gametophyte fertility (in H. grandifolius and D. anceps) or by induction of spore formation (in Desmarestia sp. and P. antarcticus). Young sporophytes of all species showed a growth optimum from September to December (-February). Desmarestia sp. and P. antarcticus produced spores and degenerated subsequently after one year of culture at 3 mol photons m–2 s–1 or after 22 months of culture at 2 mol m–2 s–1. In D. anceps spores were released without degeneration of the mother plants after 20 and 19 months of culture at 3 and 10 olm–2 s–1, respectively. In H. grandifolius spore formation was not observed. Adult one year old plants of the latter two perennial species showed growth optima between September and November. Microthalli of A. utricularis were the dominant life phase of this alga in winter. Macrothalli started to develop from June onwards at 3 mol m–2 s–1 or from August to September at 2 mol m–2 s–1. Growth rates of macrothalli cultivated at 9 mol m–2 s–1 showed a growth optimum from September to November. The macrothalli released spores from January to February. Macrothalli cultivated at 3 mol m–2 s–1 maximally grew in January. They became fertile after almost 2 years of culture at 3 mol m–2 s–1 and remained vegetative at 2 mol m–2 s–1. A. mirabilis exhibited a prominent growth optimum from August to October, at photon fluence rates between 2 and 47 mol m–2 s–1. A second optimum was evident from January to March in plants cultivated at 9 mol m–2 s–1. The results closely correspond to available field data and indicate that the phenology of the studied species can be controlled in the laboratory solely by simulating Antarctic daylengths conditions. The light requirements for growth were very low in microthalli and in juvenile macrothalli and growth was mostly light saturated at 4–12 mol m–2 s–1. Few-celled sporophytes of H. grandifolius and D. anceps tolerated at least 8 and 11 months of darkness. The minimum light demands for completion of the life cycle are 31.4 mol m–2 year–1 in Desmarestia sp., P. antarcticus and probably also in the 2 perennial Desmarestiales; 47.1 mol m–2 year–1 are needed in A. utricularis and probably also in A. mirabilis. These values predict a lower distribution limit of the investigated species at 53±23 m or 48±21 m in clear offshore waters and at 28±5 m or 26±5 m, respectively, in inshore fjords of the Antarctic Peninsula region.Contribution No. 281 of the Alfred-Wegener-Institut für Polar-u. Meeresforschung 相似文献
6.
D. Haisel P. Hofman M. Vágner H. Lipavská I. Tichá C. Schäfer V. apková 《Biologia Plantarum》2001,44(3):321-324
Plant phenotype stability during ex vitro growth, one of the main requirements of plant micropropagation, was tested on tobacco. Plants cultivated in vitro in the presence of 3 % sucrose under photon flux density (PFD) of 200 mol m–2 s–1 (3 % HL plants) showed the best growth and photosynthetic parameters in the course of 7-day acclimation. However, significant change in phenotype of these plants appeared under a decrease in PFD to 50 mol m–2 s–1 during further ex vitro growth (in the period of 7th – 17th day). Much higher internodia elongation was found in 3 % HL plants in comparison with plants grown in vitro on sucrose media under PFD of 50 mol m–2 s–1 (3 % LL) or without sucrose either under PFD of 50 mol m–2 s–1 or 200 mol m–2 s–1 (0 % LL, 0 % HL). It can be presumed that 3 % HL plants show permanent demand for high PFD. Neither ABA or chlorophyll contents nor de novo thylakoid membrane synthesis were related to the morphogenic effect of low PFD. Changeable contents of hexoses in leaves of 3 % HL and 3 % LL plants were in no direct correlation to the elongated growth. 相似文献
7.
Anne Kathrine Hvoslef-Eide 《Plant Cell, Tissue and Organ Culture》1992,28(2):167-174
In vitro cultures of Nephrolepis exaltata and Cordyline fruticosa were stored at 5°, 9° or 13°C, at a low irradiance (3–5 mol m–2 s–1) or in darkness. Prior to storage the cultures were subjected to 18°, 21°, 24° or 27°C and 15, 30 or 45 mol m–2 s–1 in a factorial combination.The optimal storage conditions for Nephrolepis were 9°C in complete darkness. These cultures were still transferable to a peat/perlite mixture at the end of the experimental period of 36 months.The optimal storage conditions for Cordyline were 13°C and a low light level (±3–5 mol m-2 s-1). When the pre-storage conditions were normal growth room conditions (24°C and 30 mol m-2 s-1), in vitro cultures could be stored for 18 months. With the most favourable pre-storage treatment (18°C and 15 mol m-2 s-1) some cultures still had green shoots after 36 months of storage, but did not survive transfer to peat/perlite.Pre-conditioning before storage was most favourable for Nephrolepis, and not that important, but still favourable, for Cordyline. There was an interaction between pre-storage temperature and pre-storage irradiance. For both species a high irradiance level was less favourable than a low irradiance level when combined with high growth room temperatures.Abbreviations BA
6-benzyladenine
- IAA
indole-3-acetic acid
- NOA
2-naphthoxyacetic acid 相似文献
8.
The increase in growth, determined by dry weight gain, of rice (Oryza sativa L.) and maize (Zea mays L.) caused by foliar applications of 9--L(+) adenosine, a putative second messenger elicited by triacontanol, was studied under different environmental conditions. Maize seedlings cultured in the greenhouse under approximately 100 mol m–2s–1 of light prior to treatment with L(+) adenosine did not respond unless they received supplemental light (250–300 mol m–2s–1) after treatment. Exposure of rice seedlings growing for 16 h at 150 mol m–2s–1 to short periods of 450 mol m–2s–1 (< than 20 min) had no effect on the positive response of rice to L(+) adenosine; however, exposure for 60 min or more increased the growth of rice and obviated the effect of L(+) adenosine. Rice seedlings treated with L(+) adenosine at different times during the day responded only when treated 9 to 12h after initiation of the photoperiod. Normal growing temperatures under different light intensities had little or no direct effect on the response of plants to L(+) adenosine. 相似文献
9.
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
10.
Biochemical and biophysical parameters, including D1-protein turnover, chlorophyll fluorescence, oxygen evolution activity and zeaxanthin formation were measured in the marine seagrassZostera capricorni (Aschers) in response to limiting (100 mol·m–2·–1), saturating (350 mol·m–2·s–1) or photoinhibitory (1100 mol·m–2·s–1) irradiances. Synthesis of D1 was maximal at 350 mol·m–2·s–1 which was also the irradiance at which the rate of photosynthetic O2 evolution was maximal. Degradation of D1 was saturated at 350 mol·m–2·s–1. The rate of D1 synthesis at 1100 mol·m–2·s–1 was very similar to that at 350 mol·m–2·s–1 for the first 90 min but then declined. At limiting or saturating irradiance little change was observed in the ratio of variable to maximal fluorescence (Fv/Fm) measured after dark adaptation of the leaves, while significant photoinhibition occurred at 1100 mol·m–2·s–1. The proportion of zeaxanthin in the total xanthophyll pool increased with increasing irradiance, indicative of the presence of a photoprotective xanthophyll cycle in this seagrass. These results are consistent with a high level of regulatory D1 turnover inZostera under non-photoinhibitory irradiance conditions, as has been found previously for terrestrial plants.We would like to thank Professor Peter Böger (Department of Plant Biochemistry, University of Konstanz, Germany) for the kind gift of D1 antibodies. This work was partly supported by a University of Queensland Enabling Grant to CC. 相似文献
11.
Efficiency of photosynthesis in continuous and pulsed light emitting diode irradiation 总被引:4,自引:0,他引:4
The light utilization efficiency and relative photon requirement of photosynthesis in pulsed and continuous light from light emitting diodes (LEDs) has been measured. First, we chacterized the photon requirement of photosynthesis from light of LEDs that differ in spectral quality. A photon requirement of 10.3±0.4 was measured using light from a 658 nm peak wavelength (22 nm half band width) LED over the range of 0–50 mol photons m–2 s–1 in 2 kPa O2 in leaves of tomato (Lycopersicon esculentum Mill., cv. VF36). Because the conversion of electrical power to photons increased with wavelength, LED lamps with peak photon output of 668 nm were most efficient for converting electricity to photosynthetically fixed carbon. The effect of pulsed irradiation on photosynthesis was then measured. When all of the light to make the equivalent of 50 mol photons m–2 s–1 was provided during 1.5 s pulses of 5000 mol photons m–2 s–1 followed by 148.5 s dark periods, photosynthesis was the same as in continuous 50 mol photons m–2 s–1. When the pulse light and dark periods were lengthened to 200 s and 19.8 ms, respectively, photosynthesis was reduced, although the averaged photon flux density was unchanged. Under these conditions, the light pulses delivered 1017 photons m–2, which we calculate to be equivalent to the capacitance of PS I or PS II. Data support the theory that photons in pulses of 100 s or shorter are absorbed and stored in the reaction centers to be used in electron transport during the dark period. When light/dark pulses were lengthened to 2 ms light and 198 ms dark, net photosynthesis was reduced to half of that measured in continuous light. Pigments of the xanthophyll cycle were not affected by any of these pulsed light treatments even though zeaxanthin formation occurred when leaves were forced to dissipate an equal amount of continuous light.Abbreviations CWF
cool white fluorescent
- EPS
xanthophyll epoxidation state
- LED
light emitting diode
- LUE
light utilization efficiency
- PFD
photon flux density
- PR
photon requirement (for CO2 fixation)
- PS II
primary donor in Photosystem II
- RPR
relative photon requirement 相似文献
12.
Effects of light and temperature, on the growth of three freshwater green algae isolated from an eutrophic lake and identified as Selenastrum minutum, Coelastrum microporum f. astroidea and Cosmarium subprotumidumwere studied in batch cultures under non-nutrient limited conditions. Experiments were performed to determine the growth rate over a wide range of light intensities (30–456 mol m–2 s–1) and temperature (15–35°C), using a 15/9 (light/dark) photoperiod cycle. The maximum growth rates and the optimum light intensities at a temperature of 35°C were 1.73 d–1 and 420 mol m–2 s–1for Selenastrum minutum, 1.64 d–1 and 400 mol m–2 s–1 for Coelastrum microporum and 1.00 d–1 and 400 mol m–2 s1 for Cosmarium subprotumidum. The results were fitted with the mathematical models of Steele (1965), Platt & Jassby (1976) and Peeters & Eilers (1978). Steele's function and equation of Platt & Jassby don't describe correctly the relationship between the growth and light intensity. In the opposite, the equation of Peeters & Eilers provides the best fit for the three species. 相似文献
13.
Photosystem 2 (PS2)-driven electron transfer was studied in primary leaves of barley (Hordeum vulgare L.) seedlings grown under various photon fluxes (0.3–170.0 mol m–2 s–1) of blue (BR) or red (RR) radiation using modulated chlorophyll fluorescence. The Fv/Fm ratio was 0.78–0.79 in leaves of all radiation variants, except in seedlings grown under BR or RR of 0.3 mol m–2 s–1. The extent of the photochemical phase of the polyphasic Fv rise induced by very strong white light was similar in leaves of all radiation treatments. Neither radiation quality nor photon flux under plant cultivation influenced the amount of non QB-transferring centres of PS2 except in leaves of seedlings grown under BR of 0.3 mol m–2 s–1, in which the amount of such centres increased threefold. Both BR and RR stimulated the development of photochemically competent PS2 at photon fluxes as low as 3 mol m–2 s–1. Three exponential components with highly different half times were distinguished in the kinetics of Fv dark decay. This indicates different pathways of electron transfer from QA
–, the reduced primary acceptor of PS2, to other acceptors. Relative magnitudes of the individual decay components did not depend on the radiation quality or the photon flux during plant cultivation. Significant differences were found, however, between plants grown under BR or RR in the rate of the middle and fast components of Fv dark decay, which showed 1.5-times faster intersystem linear electron transport in BR-grown leaves. 相似文献
14.
Analysis of gas exchange in seedlings of Acer saccharum: integration of field and laboratory studies
In the field, photosynthesis of Acer saccharum seedlings was rarely light saturated, even though light saturation occurs at about 100 mol quanta m-2 s-1 photosynthetic photon flux density (PPFD). PPFD during more than 75% of the daylight period was 50 mol m-2 s-1 or less. At these low PPFD's there is a marked interaction of PPFD with the initial slope (CE) of the CO2 response. At PPFD-saturation CE was 0.018 mol m-2 s-1/(l/l). The apparent quantum efficiency (incident PPFD) at saturating CO2 was 0.05–0.08 mol/mol.
and PPFD-saturated CO2 exchange was 6–8 mol m-2 s-1. The ratio of internal CO2 concentration to external (C
i
/C
a
) was 0.7 to 0.8 except during sunflecks when it decreased to 0.5. The decrease in C
i
/C
a
during sunflecks was the result of the slow response of stomates to increased PPFD compared to the response of net photosynthesis. An empirical model, which included the above parameters was used to simulate the measured CO2 exchange rate for portions of two days. Parameter values for the model were determined in experiments separate from the daily time courses being sumulated. Analysis of the field data, partly through the use of simulations, indicate that the elimination of sunflecks would reduce net carbon gain by 5–10%.List of symbols
A
measured photosynthetic rate under any set of conditions (mol m-2 s-1)
-
A
m
(atm)
measured photosynthetic rate at saturating PPFD, 350 l/l CO2 and 21% (v/v) O2 (mol m-2 s-1)
-
C
constant in equation of Smith (1937, 1938)
-
C
a
CO2 concentration in the air (l/l)
-
C
i
CO2 concentration in the intercellular air space (l/l)
-
C
i
/*
C
i
corrected for CO2 compensation point, i.e., C
i
-I
*, (l/l)
- CE
initial slope of the CO2 response of photosynthesis (mol m-2 s-1/(l/l))
- CEM
CE at PPFD saturation
-
E
transpiration rate (mmol m-2 s-1)
-
F
predicted photosynthetic rate (mol m-2 s-1)
-
G
leaf conductance to H2O (mol m-2 s-1)
-
I
photosynthetic photon flux density (mol m-2 s-1)
-
N
number of data points
-
P
m
predicted photosynthetic rate at saturating CO2 and given PPFD (mol m-2 s-1)
-
P
ml
predicted photosynthetic rate at saturating CO2 and PPFD (mol m-2 s-1)
-
R
d
residual respiratory rate (mol m-2 s-1)
-
T
a
air temperature (°C)
-
T
l
leaf temperature (°C)
-
V
reaction velocity in equation of Smith (1937, 1938)
-
V
max
saturated reaction velocity in equation of Smith (1937, 1938)
- VPA
vapor pressure of water in the air (mbar/bar)
- VPD
vapor pressure difference between leaf and air (mbar/bar)
-
X
substrate concentration in equation of Smith (1937, 1938)
-
initial slope of the PPFD response of photosynthesis at saturating CO2 (mol CO2/mol quanta)
- (atm)
initial slope of the PPFD response of photosynthesis at 340 l/l CO2 and 21% (v/v) O2 (mol CO2/mol quanta)
-
I
*
CO2 compensation point after correction for residual respiration (l/l)
-
PPFD compensation point (mol m-2 s-1) 相似文献
15.
Stefan Falk Jerry W. Leverenz Göran Samuelsson Gunnar Öquist 《Photosynthesis research》1992,31(1):31-40
The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200 mol m–2s–1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780 mol m–2s–1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600 mol m–2s–1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of QB-reducing centers and 3) a second photoinhibitory range above 1600 mol m–2s–1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS II centers and a large increase in spill-over in energy to PS I.Abbreviations Chl
chlorophyll
- DCMU
3,(3,4-dichlorophenyl)-1,1-dimethylurea
- FM
maximal fluorescence yield
- Fpl
intermediate fluorescence yield plateau level
- F0
non-variable fluorescence yield
- Fv
total variable fluorescence yield (FM-F0)
-
initial slope to the light response curve, used as an estimate of initial quantum yield
-
convexity (rate of bending) of the light response curve of photosynthesis
- LHC
light-harvesting complex
- Pmax
maximum rate of photosynthesis
- PQ
plastoquinone
- Q
photosynthetically active photon flux density (400–700 nm, mol m–2s–1)
- PS
photosystem
- QA and QB
primary and secondary quinone electron acceptor of PS II 相似文献
16.
Leaf photosynthetic rates were measured on field-grown soybeans during the 1980 season. Comparisons were made between different cultivars and isolines representative of maturity groups I–IV. Mature, fully expanded leaves at different nodes on the plant were measured in high light to determine which had the highest potential photosynthetic rates at any one time. Successive leaves during the growing season had maximum rates which increased from about 22 mol CO2 m-2 s-1 on 25 June to a peak of 30–44 mol CO2 m-2 s-1 in early August.The persistency and eventual decline in the maximum rate was associated with the maturity group and related dates of flowering, pod fill and onset of senescence. Early maturing cultivars (groups I and II) had higher peak rates (38–44 mol CO2 m-2 s-1) than later maturing cultivars (30–35 mol CO2 m-2 s-1, groups III and IV). However, the photosynthetic rates of early maturing cultivars declined rapidly after attaining their peak, whereas the leaves of later maturing cultivars maintained their photosynthetic activity for much longer. 相似文献
17.
Salguero A León R Mariotti A de la Morena B Vega JM Vílchez C 《Applied microbiology and biotechnology》2005,66(5):506-511
The effect of adding UV-A radiation (320–400 nm) to photosynthetically active radiation (PAR, 400–700 nm) during growth of the photosynthetic marine microalga Dunaliella bardawil was investigated in this work in terms of cell growth and carotenoid production. Although signs of slow cell growth (slight reduction of chlorophyll and protein content) were observed after 24 h of cell exposure to UV-A (40 mol photons m–2 s–1 and 70 mol photons m–2 s–1) plus 140 mol photons m–2 s–1 PAR , 84 h exposure to these UV-A conditions slightly stimulated cell growth and increased the photosynthetic efficiency of the exposed cultures. The enhanced cell growth was coupled with an increase in total carotenoid content. Besides -carotene as the major pigment, increases in the well-known antioxidants lutein and zeaxanthin of about 3-fold and 5-fold, respectively, were determined in cultures exposed to UV-A radiation of 70 mol photons m–2 s–1for 84 h. As a consequence, far from being negative to cell growth, low and medium UV-A radiation are stress factors that could be successfully applied to long-term processes for large scale carotenoid production using D. bardawil cultures with retention of cell viability. UV-A exposure has the advantage of being a factor either easily applied or removed as required, in contrast to other nutrient stresses, which require medium replacement for their application. 相似文献
18.
Carvalho Luisa C. Leonor Osório M. Manuela Chaves M. Amâncio Sara 《Plant Cell, Tissue and Organ Culture》2001,67(3):271-280
This study reports the effects of light availability during the acclimatization phase on photosynthetic characteristics of micropropagated plantlets of grapevine (Vitis vinifera L.) and of a chestnut hybrid (Castanea sativa × C. crenata). The plantlets were acclimatized for 4 weeks (grapevine) or 6 weeks (chestnut), under two irradiance treatments, 150 and 300 mol m–2 s–1 after in vitro phases at 50 mol m–2 s–1. For both treatments and both species, leaves formed during acclimatization (so-called `new leaves') showed higher photosynthetic capacity than the leaves formed in vitro either under heterotrophic or during acclimatization (so-called `persistent leaves'), although lower than leaves of young potted plants (so-called `greenhouse leaves'). In grapevine, unlike chestnut, net photosynthesis and biomass production increased significantly with increased light availability. Several parameters associated with chlorophyll a fluorescence indicated photoinhibition symptoms in chestnut leaves growing at 300 mol m–2 s–1. The results taken as a whole suggest that 300 mol m–2 s–1 is the upper threshold for acclimatization of chestnut although grapevine showed a better response than chestnut to an increase in light. 相似文献
19.
Severely yellowed ten-year-old spruce trees growing in the Vosges Mountains on an acidic soil were fertilised with Magnesium lime during the spring of 1990. The effects of this treatment were assessed 18 months later. A very significant improvement of the mineral status of the trees was detected, with increasing Mg contents in the needles, and as a consequence, reduced yellowing and improved chlorophyll content. Only slight differences with control trees were observed for height increase. Effects of this improved nutrition on photosynthesis were tested measuring net CO2 assimilation rates and chlorophyll a fluorescence. Light-saturated net assimilation rates of current-year needles were high, reaching 5.3 mol m–2 s–1 on a total needle area basis. The improvement in chlorophyll and Mg content had no significant effect on net assimilation rates or on any parameter describing photochemical functions of both current-and previous-year needles. Despite the strong inter-individual variability in needle chlorophyll and Mg contents (ranging from 0.2 to 0.8 mg g–1 fresh weight, and 0.05 to 0.5 mg g-1 dry weight respectively), photochemical efficiency of PS II under limiting irradiance only decreased significantly on older needles displaying Mg contents below 0.1 mg g–1. It is concluded from these results that spruce trees exhibit a high degree of plasticity with regard to Mg deficiency on acidic soils, and that improved Mg nutrition and increased chlorophyll content do not necessarily improve photosynthesis and height growth.Abbreviations A
light-saturated net CO2 assimilation rate (mol m–2 s–1)
- gw
light-saturated needle conductance to water vapour (mmol m–2 s–1)
- wp and wm
pre-dawn and mid-day needle water potential (MPa)
-
osmotic potential of sap expressed from needles (MPa)
- PFD
photosynthetic photon flux density (mol m–2 s–1)
- Fv/Fm
photochemical efficiency of PS II after 20 min dark adaptation
- F/Fm
'
photochemical efficiency of PS II reaction centres after 10 min at a PFD of 220 mol m–2 s–1 相似文献
20.
E. A. C. MacRobbie 《The Journal of membrane biology》1980,53(3):189-198
Summary Observations of aperture changes as sucrose is added to the solution bathing epidermal strips ofCommelina communis L. allow calculation of the osmotic changes required to open or close the stomatal pore, for comparison with changes in potassium content. With isolated guard cells, in strips in which all cells other than guard cells have been killed, the internal osmotic changes required are 83 mosmol kg–1 m–1 below 10m aperture, 129 mosmol kg–1 m–1 in the range 10–15 m, and 180 mosmol kg–1 m–1 above 15 m. For opening against subsidiary cell turgor in addition to guard cell turgor, in intact strips with live subsidiary and epidermal cells, these figures should each be increased by about 33 mosmol kg–1 m–1. A change in subsidiary cell turgor is magnified in its effects on the water relations of the guard cell by a factor greater than 3.7 for equal changes in the water potential of the two cells, or greater than 4.7 at constant volume of the guard cell. 相似文献