共查询到20条相似文献,搜索用时 437 毫秒
1.
A. E. Solovchenko I. Khozin-Goldberg S. Didi-Cohen Z. Cohen M. N. Merzlyak 《Journal of applied phycology》2008,20(3):245-251
The effects of light and nitrogen deficiency on biomass, fatty acid content and composition were studied in Parietochloris incisa, the unicellular freshwater chlorophyte accumulating very high amounts of arachidonic-acid-rich triacylglycerols. P. incisa cultures grown on complete nutrient medium and under high light (400 μmol photons m− 2 s−1) showed the highest rate of growth in comparison to medium (200 μmol photons m−2 s−1) and low (35 μmol photons m−2 s−1) light intensity. Cultures grown under high light (on complete BG-11 medium) attained higher volumetric contents of total
fatty acids and arachidonic acid due to greater increase in biomass. Nitrogen starvation brought about a strong increase in
the arachidonic acid proportion of total fatty acids. Thus, adjustments to cultivation conditions could serve as an efficient
tool for manipulation of yield and relative content of arachidonic acid in P. incisa. The significance of the changes in lipid metabolism for adaptation of P. incisa to high-light stress and nitrogen deficiency is also discussed. 相似文献
2.
Ganka Chaneva Sevdalina Furnadzhieva Kaledona Minkova Jaromir Lukavsky 《Journal of applied phycology》2007,19(5):537-544
The effect of light intensity (50–300 μmol photons m−2 s−1) and temperature (15–50°C) on chlorophyll a, carotenoid and phycobiliprotein content in Arthronema africanum biomass was studied. Maximum growth rate was measured at 300 μmol photons m−2 s−1 and 36°C after 96 h of cultivation. The chlorophyll a content increased along with the increase in light intensity and temperature and reached 2.4% of dry weight at 150 μmol photons
m−2 s−1 and 36°C, but it decreased at higher temperatures. The level of carotenoids did not change significantly under temperature
changes at illumination of 50 and 100 μmol photons m−2 s−1. Carotenoids were about 1% of the dry weight at higher light intensities: 150 and 300 μmol photons m−2 s−1. Arthronema africanum contained C-phycocyanin and allophycocyanin but no phycoerythrin. The total phycobiliprotein content was extremely high,
more than 30% of the dry algal biomass, thus the cyanobacterium could be deemed an alternative producer of C-phycocyanin.
A highest total of phycobiliproteins was reached at light intensity of 150 μmol photons m−2 s−1 and temperature of 36°C, C-phycocyanin and allophycocyanin amounting, respectively, to 23% and 12% of the dry algal biomass.
Extremely low (<15°C) and high temperatures (>47°C) decreased phycobiliprotein content regardless of light intensity. 相似文献
3.
Summary
In vitro banana (Musa spp.) shoots were cultured under photomixotrophic (30 gl−1 sucrose and 0.2 h−1 number of air exchanges of culture vessels) and photoautotrophic (0 gl−1 sucrose and 3.9 h−1 number of air exchanges) conditions for 28 d in 370 cm3 Magenta boxes (GA7-type) containing 70 ml of half-strength Murashige and Skoog (MS) medium with 22.2 μM N6-benzyladenine (BA). The effects of varying CO2 concentration (475 or 1340 μmol mol−1) and light intensity (photosynthetic photon flux (PPF) of 100 or 200 μmol m−2 s−1) were investigated. Fresh and dry weights of banana shoots grown photomixotrophically were significantly greater on day 28
than those grown photoautotrophically. Photoautorophic shoots had a larger number of unfolded leaves and greater leaf area
than photomixotrophic plants by days 14 and 28, regardless of CO2 concentration. The shoot fresh and dry weights on day 14 in photoautotrophic conditions were significantly greater at PPF
of 200 μmol m−2 s−1 than at 100 μmol m−2 s−1. The increase in net photosynthetic rate of photoautotrophic banana shoots was significant compared with photomixotrophic
shoots. The multiplication ratio of in vitro banana shoots grown photoautotrophically in a 28-d culture period was the greatest at 100 μmol m−2 s−1 PPF and 475 μmol mol−1 CO2. 相似文献
4.
Hemant Lata Suman Chandra Ikhlas Khan Mahmoud A. ElSohly 《In vitro cellular & developmental biology. Plant》2009,45(1):12-19
Induction of high-frequency shoot regeneration using nodal segments containing axillary buds from a 1-yr-old mother plants
of Cannabis sativa was achieved on Murashige and Skoog (MS) medium containing 0.05–5.0 μM thidiazuron. The quality and quantity of regenerants
were better with thidiazuron (0.5 μM thidiazuron) than with benzyladenine or kinetin. Adding 7.0 μM of gibberellic acid into
a medium containing 0.5 μM thidiazuron slightly increased shoot growth. Elongated shoots when transferred to half-strength
MS medium supplemented with 500 mg l−1 activated charcoal and 2.5 μM indole-3-butyric acid resulted in 95% rooting. The rooted plants were successfully acclimatized
in soil. Following acclimatization, growth performance of 4-mo-old in vitro propagated plants was compared with ex vitro vegetatively grown plants of the same age. The photosynthesis and transpiration characteristics were studied under different
light levels (0, 500, 1,000, 1,500, or 2,000 μmol m−2 s−1). An increase in photosynthesis was observed with increase in the light intensity up to 1,500 μmol m−2 s−1 and then decreased subsequently at higher light levels in both types of plants. However, the increase was more pronounced
at lower light intensities below 500 μmol m−2 s−1. Stomatal conductance and transpiration increased with light intensity up to highest level (2000 μmol m−2 s−1) tested. Intercellular CO2 concentration (C
i) and the ratio of intercellular CO2 concentration to ambient CO2 (C
i/C
a) decreased with the increase in light intensity in both in vitro as well as ex vitro raised plants. The results show that in vitro propagated and hardened plants were functionally comparable to ex vitro plants of same age in terms of gas and water vapor exchange characteristics, within the limits of this study. 相似文献
5.
The relationship between O2-based gross photosynthesis (GP) and in vivo chlorophyll fluorescence of Photosystem II-based electron transport rate (ETR) as well as the relationship between effective
quantum yield of fluorescence (ΦPSII) and quantum yield of oxygen evolution (ΦO_2) were examined in the green algae Ulva rotundata and Ulva olivascens and the red alga Porphyra leucosticta collected from the field and incubated for 3 days at 100 μmol m−2 s−1 in nutrient enriched seawater. Maximal GP was twice as high in Ulva species than that measured in P. leucosticta. In all species ETR was saturated at much higher irradiance than GP. The initial slope of ETR versus absorbed irradiance
was higher than that of GP versus absorbed irradiance. Only under absorbed irradiances below saturation or at values of GP <2 μmol O2 m−2 s−1 a linear relationship was observed. In the linear phase, calculated O2 evolved /ETR molar ratios were closed to the theoretical value of 0.25 in Ulva species. In P. leucosticta, the estimated GP was associated to the estimated ETR only at high irradiances. ETR was determined under white light, red
light emitting by diodes and solar radiation. In Ulva species the maximal ETR was reached under red light and solar radiation whereas in P. leucosticta the maximal ETR was reached under white light and minimal under red light. These results are in agreement with the known
action spectra for photosynthesis in these species. In the case of P. leucosticta, GP and ETR were additionally determined under saturating irradiance in algae pre-incubated for one week under white light
at different irradiances and at white light (100 μmol m−2 s−1) enriched with far-red light. GP and growth rate increased at a growth irradiance of 500 μmol m−2 s−1 becoming photoinhibited at higher irradiances, while ETR increased when algae were exposed to the highest growth irradiance
applied (2000 μmol m−2 s−1). The calculated O2 evolved /ETR molar ratios were close to the theoretical value of 0.25 when algae were pre-incubated under 500–1000 μmol m−2 s−1. The enrichment by FR light provoked a decrease in both GP and ETR and an increase of nonphotochemical quenching although
the irradiance of PAR was maintained at a constant level. In addition to C assimilation, other electron sinks, such as nitrogen
assimilation, affected the GP–ETR relationship. The slopes of GP versus ETR or ΦPSII
versus ΦO_2 were lower in the algae with the highest N assimilation capacity, estimated as nitrate reductase activity and internal nitrogen
contents, i.e., Ulva rotundata and Porphyra leucosticta, than that observed in U. olivascens. The possible mechanisms to explain this discrepancy between GP and ETR are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Using 77 K chlorophyll a (Chl a) fluorescence spectra in vivo, the development was studied of Photosystems II (PS II) and I (PS I) during greening of barley under intermittent light followed
by continuous light at low (LI, 50 μmol m−2 s−1) and high (HI, 1000 μmol m−2 s−1) irradiances. The greening at HI intermittent light was accompanied with significantly reduced fluorescence intensity from
Chl b excitation for both PS II (F685) and PS I (F743), in comparison with LI plants, indicating that assembly of light-harvesting
complexes (LHC) of both photosystems was affected to a similar degree. During greening at continuous HI, a slower increase
of emission from Chl b excitation in PS II as compared with PS I was observed, indicating a preferred reduction in the accumulation of LHC II. The
following characteristics of 77 K Chl a fluorescence spectra documented the photoprotective function of an elevated content of carotenoids in HI leaves: (1) a pronounced
suppression of Soret region of excitation spectra (410–450 nm) in comparison with the red region (670–690 nm) during the early
stage of greening indicated a strongly reduced excitation energy transfer from carotenoids to the Chl a fluorescing forms within PS I and PS II; (2) changes in the shape of the excitation band of Chl b and carotenoids (460–490 nm) during greening under continuous light confirmed that the energy transfer from carotenoids to
Chl a within PS II remained lower as compared with the LI plants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
The activity of 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (DS-Mn, DS-Co), phenylalanine ammonia-lyase (PAL),
and chalcone synthase (CHS) was monitored at various light intensities (dark, 8.88 μmol m−2 s−1, 88.8 μmol m−2 s−1) using a strawberry cell suspension culture. DS-Mn, PAL, and CHS were found to increase significantly (p>0.05) under light intensitie of 88.8 μmol m−2 s−1 compared to those of 8.88 μmol m−2 s−1 and dark. The activity of DS-Mn, PAL, and CHS were maximum at 88.8 μmol m−2 s−1. Anthocyanin content reached a maximum after 48–60 h of culturing at 88.8 μmol m−2 s−1. DS-Co showed greater activity than DS-Mn during cell culturing, but showed no correlation with anthocyanin production and
light intensity. The CHS gene expression was continuous at a light intensity of 88.8 μmol m−2 s−1.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Mohammad K. Khalesi H. H. Beeftink R. H. Wijffels 《Marine biotechnology (New York, N.Y.)》2009,11(4):488-494
The branching zooxanthellate soft coral Sinularia flexibillis releases antimicrobial and toxic compounds with potential pharmaceutical importance. As photosynthesis by the symbiotic algae
is vital to the host, the light-dependency of the coral, including its specific growth rate (μ day−1) and the physiological response to a range of light intensities (10–1,000 μmol quanta m−2 s−1) was studied for 12 weeks. Although a range of irradiances from 100 to 400 μmol quanta m−2 s−1 was favorable for S. flexibilis, based on chlorophyll content, a light intensity around 100 μmol quanta m−2 s−1 was found to be optimal. The contents of both zooxanthellae and chlorophyll a were highest at 100 μmol quanta m−2 s−1. The specific budding rate showed almost the same pattern as the specific growth rate. The concentration of the terpene flexibilide,
produced by this species, increased at high light intensities (200–600 μmol quanta m−2 s−1). 相似文献
9.
Domínguez-Bocanegra AR Ponce-Noyola T Torres-Muñoz JA 《Applied microbiology and biotechnology》2007,75(4):783-791
Phaffia rhodozyma (now Xanthophyllomyces dendrorhous) and Haematococcus pluvialis are known as the major prominent microorganisms able to synthesize astaxanthin natural pigment. Important research efforts
have been made to determine optimal conditions for astaxanthin synthesis. When the focus is on astaxanthin production, the
maximal reported value of 9.2 mg/g cell is obtained within H. pluvialis grown on BAR medium, under continuous illumination (345 μmol photon m−2 s−1) and without aeration. Whereas fermentation by mutated R1 yeast grown on coconut milk produced 1,850 μg/g yeast. However,
when looking at astaxanthin productivity, the picture is slightly different. The figures obtained with P. rhodozyma are rather similar to those of H. pluvialis. Maximal reported values are 170 μg/g yeast per day with a wild yeast strain and 370 μg/g yeast per day with mutated R1 yeast.
In the case of H. pluvialis, maximal values ranged from 290 to 428 μg/g cell per day depending on the media (BG-11 or BAR), light intensity (177 μmol
photon m−2 s−1), aeration, etc. The main aim of this work was to examine how astaxanthin synthesis, by P. rhodozyma and H. pluvialis, could be compared. The study is based on previous works by the authors where pigment productions have been reported. 相似文献
10.
The effects of UVB on the kinetics of stem elongation of wild type (WT) and photomorphogenic mutants of tomato were studied
by using linear voltage transducers connected to a computer. Twenty-one or twenty-six-day-old plants, grown in 12 h white
light (150 μmol m−2 s−1 PAR)/12 h dark cycles, were first transferred to 200 μmol m−2 s−1 monochromatic yellow light for 12 h, then irradiated with 0.1 or 4.5 μmol m−2 s−1 UVB for 12 h and finally kept in darkness for another 24 h. The measurements of the kinetics of stem elongation started after
4 h under yellow light. Significant differences in stem growth during the irradiation with yellow light, as well as during
the dark period, were found between the genotypes. In darkness, the magnitude of stem growth followed the order: tri > AC = fri > MMau > hp1. Two factors determined the large differences of growth in darkness: 1) the different stem elongation rate (SER) and 2) the
different duration of the growing phase among the genotypes. In darkness the stem growth of au and hp1 mutants lasted for about 18 h, whereas it continued for the whole experimental period (36 h) in the other genotypes. UVB
irradiation substantially reduced elongation growth of all genotypes (4.5 μmol m−2 s−1 being more effective than 0.1 μmol m−2 s−1). Both fluence rates of UVB induced a detectable reduction of SER already after 15 min of irradiation. Red light inhibited,
while far red light promoted stem growth of all the genotypes tested. fri (phyA null), tri (phyB1 null), hp1 (exhibiting exaggerated phytochrome responses) mutants and WT tomato showed similar levels of UVB–induced inhibition of growth,
while the aurea mutant showed the largest growth inhibition during the 12 h of irradiation. These results indicate that phytochrome is not
directly involved in UVB control of stem elongation. The results of dichromatic irradiations UVB + red or UVB + far red indicate
the presence of distinct and additive action of UVB photoreceptor and of the phytochrome system in the photoregulation of
stem growth.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Summary The effects were studied of light intensity, culture method and cytokinins on plant formation from callus-derived rhizomes
of Cymbidium ensifolium var. misericors. The results demonstrated that one piece of rhizome produced seven shoot buds in 45 d when cultured in 1/2 MS basal liquid
medium supplemented with 0.17 μM N6-(2-isopentenyl) adenine, 0.17 μM thidiazuron, 33 μM 6-aminopurine adenine and 1.5 μM naphthaleneacetic acid under 10 μmol m−2 s−1 artificial light and agitated at 60 rpm on a rotary shaker. These shoot-cm plantlets in 5 mo. when transferred to the same
Gelrite-gel basal medium supplemented with 50 g l−1 banana pulp. Plantlets were acclimated and grew well when potted in the greenhouse. 相似文献
12.
The eco-physiological responses of three nitrogen-fixing cyanobacteria (N-fixing cyanobacteria), Aphanizomenon gracile, Anabaena minderi, and Ana. torques-reginae, to light were assessed under nutrient saturation. The N-fixing cyanobacteria were isolated into monocultures from a natural
bloom in a shallow colored lake and their growth irradiance parameters and pigment composition were assessed. The different
ecological traits related to light use (μmax, α, I
k) suggest that these N-fixing cyanobacteria are well adapted to low light conditions at sufficient nutrients, yet interspecific
differences were observed. Aphanizomenon gracile and Anabaena minderi had high relative growth rates at low irradiances (ca. 70% of those in high light), low half saturation constant for light-limited
growth (I
k < 9.09 μmol photon m−2 s−1) and high efficiency (α < 0.11 day−1 μmol photon−1 m2 s). Conversely, Ana. torques-reginae showed poorer light competitiveness: low relative growth rates at low irradiances (ca. 40% of those in high light), low α
(0.009 day−1 μmol photon−1 m2 s) and higher I
k (35.5 μmol photon m−2 s−1). Final densities in Aphanizomenon gracile and Anabaena minderi reached bloom densities at irradiances above 30 μmol photon m−2 s−1 with different hierarchy depending on irradiance, whereas Ana. torques-reginae never achieved bloom densities. All species had very low densities at irradiances ≤17 μmol photon m−2 s−1, thus no N-fixing blooms would be expected at these irradiances. Also, under prolonged darkness and at lowest irradiance
(0 and 3 μmol photon m−2 s−1) akinetes were degraded, suggesting that in ecosystems with permanently dark sediments, the prevalence of N-fixing cyanobacteria
should not be favored. All species displayed peaks of phycocyanin, but no phycoeritrin, probably due to the prevailing red
light in the ecosystem from which they were isolated. 相似文献
13.
Photosynthetic Response of Carrots to Varying Irradiances 总被引:7,自引:3,他引:4
Response to irradiance of leaf net photosynthetic rates (P
N) of four carrot cultivars: Cascade, Caro Choice (CC), Oranza, and Red Core Chantenay (RCC) were examined in a controlled
environment. Gas exchange measurements were conducted at photosynthetic active radiation (PAR) from 100 to 1 000 μmol m−2 s−1 at 20 °C and 350 μmol (CO2) mol−1(air). The values of P
N were fitted to a rectangular hyperbolic nonlinear regression model. P
N for all cultivars increased similarly with increasing PAR but Cascade and Oranza generally had higher P
N than CC. None of the cultivars reached saturation at 1 000 μmol m−2 s−1. The predicted P
N at saturation (P
Nmax) for Cascade, CC, Oranza, and RCC were 19.78, 16.40, 19.79, and 18.11 μmol (CO2) m−2 s−1, respectively. The compensation irradiance (I
c) occurred at 54 μmol m−2 s−1 for Cascade, 36 μmol m−2 s−1 for CC, 45 μmol m−2 s−1 for Oranza, and 25 μmol m−2 s−1 for RCC. The quantum yield among the cultivars ranged between 0.057–0.033 mol(CO2) mol−1(PAR) and did not differ. Dark respiration varied from 2.66 μmol m−2 s−1 for Cascade to 0.85 μmol m−2 s−1 for RCC. As P
N increased with PAR, intercellular CO2 decreased in a non-linear manner. Increasing PAR increased stomatal conductance and transpiration rate to a peak between
600 and 800 μmol m−2 s−1 followed by a steep decline resulting in sharp increases in water use efficiency.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
Low-cost alternatives for the micropropagation of banana 总被引:3,自引:0,他引:3
A 90% resource cost reduction in tissue culture of banana was achieved by replacing tissue culture grade sucrose and Gelrite
in the medium with locally available commercial sugar and a starch/Gelrite mixture and by using sun light instead of artificial
light. The micropropagation of Musa `Grande Naine' by shoot tip culture was used as model. Thirteen commercial sugars from different countries were tested. Best
results were achieved using white and light brown sugars with low electrical conductivity. Sugars of cane or sugar beet origin
were suitable. Starches of corn or potato could partially substitute for Gelrite and agar. In all experiments, micropropagation
rates under natural light conditions were equal to or higher than under the controlled conditions of a growth room with PPFD
of 65 μmol m−2 s−1 and a 16-h photoperiod. Plants were exposed to average PPFD levels of 58–96 μmol m−2 s−1 and photoperiods ranged from 8–16 hours.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
Anželika Kurilčik Renata Miklušytė-Čanova Stasė Dapkūnienė Silva Žilinskaitė Genadij Kurilčik Gintautas Tamulaitis Pavelas Duchovskis Artūras Žukauskas 《Central European Journal of Biology》2008,3(2):161-167
Effects of illumination spectrum on the morphogenesis of chrysanthemum plantlets (Chrysanthemum morifolium Ramat. ‘Ellen’) grown in vitro were studied using an illumination system consisting of four groups of light-emitting diodes (LEDs) in the following spectral
regions: blue (450nm), red (640nm), red (660nm), and far-red (735nm). Taking into account all differences in shoot height,
root length, and fresh and dry weight (FW and DW, respectively), observed while changing the total photon flux density (PFD),
the optimal total PFD for growth of chrysanthemum plantlets in vitro was estimated. For 16 h photoperiod and typical fractions of the spectral components (14%, 50%, 28%, and 8%, respectively),
the optimal total PFD was found to be 40 μmol m−2 s−1. Our study shows that the blue component in the illumination spectrum inhibits the plantlet extension and formation of roots
and simultaneously increases the DW to FW ratio and content of photosynthetic pigments. We demonstrate photomorphogenetic
effects in the blue region and its interaction with the fractional PFD of the far-red spectral component. Under constant fractional
PFD of the blue component, the root number, length of roots and stems, and fresh weight of the plantlets have a correlated
nonmonotonous dependence on the fractional PFD of the far-red component. 相似文献
16.
The purpose of this study was to clarify effects of anthocyanins on photosynthesis and photoinhibition in green and red leaves
of Oxalis triangularis. Gas analysis indicated that green plants had the highest apparent quantum yield for CO2 assimilation [0.051 vs. 0.031 μmol(CO2) μmol−1(photon)] and the highest maximum photosynthesis [10.07 vs. 7.24 μmol(CO2) m−2 s−1], while fluorescence measurements indicated that red plants had the highest PSII quantum yield [0.200 vs. 0.143 μmol(e−) μmol−1(photon)] and ETRmax [66.27 vs. 44.34 μmol(e−) m−2 s−1]. Red plants had high contents of anthocyanins [20.11 mg g−1(DM)], while green plants had low and undetectable levels of anthocyanin. Red plants also had statistically significantly
(0.05>p>0.01) lower contents of xanthophyll cycle components [0.63 vs. 0.76 mg g−1(DM)] and higher activities of the reactive oxygen scavenging enzyme ascorbate peroxidase [41.2 vs. 10.0 nkat g−1(DM)]. Anthocyanins act as a sunscreen, protecting the chloroplasts from high light intensities. This shading effect causes
a lower photosynthetic CO2 assimilation in red plants compared to green plants, but a higher quantum efficiency of photosystem II (PSII). Anthocyanins
contribute to photoprotection, compensating for lower xanthophyll content in red plants, and red plants are less photoinhibited
than green plants, as illustrated by the Fv/Fm ratio. 相似文献
17.
Sucrose and light effects on in vitro cultures of potato,chokecherry and saskatoon berry during low temperature storage 总被引:1,自引:0,他引:1
Pruski Kris Kozai Toyoki Lewis Tina Astatkie Tess Nowak Jerzy 《Plant Cell, Tissue and Organ Culture》2000,63(3):215-221
Cultures of potato (Solanum tuberosum) cv. Atlantic, chokecherry (Prunus virginiana L.) cv. Garrington and saskatoon berry (Amelancher alnifolia Nutt.) cv. Northline grown in vitro for 3 weeks at 24/22 °C, 16-h photoperiod, 150 μmol m−2 s−1 photosynthetic photon flux density (PPFD) mixed fluorescent/incandescent light were stored for 6, 9 and 12 weeks at 4 °C
under 0 (darkness) and 3 μmol m−2 s−1 PPFD (690 nm red light continuous illumination). Growth regulators free MSMO medium either with or without 30 g l−1 sucrose was used to store the cultures. All cultures retained capacity to re-grow after storage. Tested factors, sucrose,
light and the length of the storage period had an impact on shoot quality and re-growth capacity of the cultures. For either
light treatment sucrose was essential for the low temperature maintenance of vigorous stock plants of potato, if stored for
over 6 weeks. Chokecherry and saskatoon cultures stored well without sucrose; although chokecherry benefited from sucrose
in the storage medium when the stock cultures were kept at the low temperature for 12 weeks. Low light significantly improved
quality of the stored potato cultures, but had very little effect on both chokecherry and saskatoon berry cultures. The woody
plant cultures grew during storage, and the longer the stock plants were stored, the more vigorous cultures they generated.
The results indicate that growers can successfully use their existing facilities, small refrigerators and coolers with low
light intensity, set at 4 °C, for short term storage of potato, chokecherry and saskatoon berry cultures. The potato cultures,
which are known to be sensitive to prolonged low temperature storage, should be frequently monitored and subcultured as required.
On the other hand, the woody plant stock cultures do not require any special attention when kept at 4 °C and re-grow the most
vigorous shoots if stored for at least 12 weeks.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
Huguette Sallanon Monique Berger Catherine Genoud Alain Coudret 《In vitro cellular & developmental biology. Plant》1998,34(2):169-172
Summary MicropropagatedRosa hybrida plantlets were simultaneously rooted and acclimatized under 100 and 200 μmol m−2 s−1 light for 2 wk. At the end of the first week of acclimatization, the plantlets were transferred onto a low water potential
medium (from −0.06 MPa to −0.3 MPa). Dry weight was decreased by increased hight and low water potential. Photoinhibition
of photosynthesis, expressed as a decrease in Fv/Fm ratio and ΦPSII and an increase in 1 −qp, occurred in plants grown under
200 μmol m−2 s−1. When high light (200 μmol m−2 s−1) and water stress were applied simultaneously, their effects on chlorophyll fluorescence parameters depended on stress duration;
after 1 d of water stress, photoinhibition was more pronounced; after 7 d of stress, Fv/Fm ratio and ΦPSII were higher than
after 1 d of stress; photoinhibition was reduced. This suggests that after a 1-d stress, the effect of water stress alone
included a superimposed effect of photoinhibition to which the water-stressed plants were sensitized; after 7 d, plantlets
had adapted to water stress. The photoprotective effects under high light might result in energy dissipative mechanisms linked
to photochemical and nonphotochemical quenching other than CO2 fixation. 相似文献
19.
Chlorophyll-a (chl-a) and carotenoid pigments of the zooxanthellate octocoral Sinularia flexibilis were analyzed using high performance liquid chromatography following exposure to three light intensities for over 30 days.
From the coral fragments located at different light intensities, a total carotenoid of >41 μg g−1 dry weight, including peridinin, xanthophylls (likely diadinoxanthin + diatoxanthin), and chl-a as the most abundant pigments, with minor contents of astaxantin and β-carotene were detected. The whole content of chl-a weighed 5 μg g−1 dry weight in all coral colonies. Chl-a and carotenoids contributed 11.2% and 88.2%, respectively, to all pigments detected, and together accounted for 99.4% of
the total pigments present. The highest contents of carotenoids and chl-a was observed in the coral grafts placed in an irradiance of 100 μmol quanta m−2 s−1; they showed lower ratios of total carotenoids: chl-a compared to those exposed to 400 μmol quanta m−2 s−1 after >30 days of incubation. The ratios of peridinin and xanthophylls with respect to chl-a from the colonies at 400 μmol quanta m−2 s−1 were approximately double those observed at irradiances of 100 and 200 μmol quanta m−2 s−1. Partial quantification of pigments in this study showed that the carotenoids of S. flexibilis showed a decrease at irradiances above 100 μmol quanta m−2 s−1, with the exception of an increase in β-carotene at 200 μmol quanta m−2 s−1. 相似文献
20.
Lamia Trabelsi Hatem Ben Ouada Hassen Bacha Mohamed Ghoul 《Journal of applied phycology》2009,21(4):405-412
The effects of light intensity and temperature on Arthrospira platensis growth and production of extracellular polymeric substances (EPS) in batch culture were evaluated using a three-level, full-factorial
design and response surface methodology. Three levels were tested for each parameter (temperature: 30, 35, 40°C; light intensity:
50, 115, 180 μmol photons m−2 s−1). Both growth and EPS production are influenced mainly by the temperature factor but the interaction term temperature*light
intensity also had a significant effect. In addition, conditions optimising EPS production are different from those optimising
growth. The highest growth rate (0.414 ± 0.003 day−1) was found at the lowest temperature (30°C) and highest light intensity (180 μmol photons m−2 s−1) tested, no optima were detectable within the given test range. Obviously, optima for growth must be at a temperature lower
than 30°C and a light intensity higher than 180 μmol photons m−2 s−1. For EPS production, light intensity had a positive linear effect (optimum obviously higher than 180 μmol photons m−2 s−1), but for the temperature parameter a maximum effect was detectable at 35°C. 相似文献