共查询到20条相似文献,搜索用时 859 毫秒
1.
M. K. Pradhan L. Nayak P. N. Joshi P. K. Mohapatra L. Patro B. Biswal U. C. Biswal 《Photosynthetica》2008,46(3):370-377
Alterations in photosynthetic capacity of primary leaves of wheat seedlings in response to ultraviolet-B (UV-B; 280–320 nm;
60 μmol m−2 s−1) exposure alone and in combination with photosynthetically active radiation (PAR; 400–800 nm; 200 μmol m−2 s−1) during different phases of leaf growth and development were assessed. UV-B exposure resulted in a phase-dependent differential
loss in photosynthetic pigments, photochemical potential, photosystem 2 (PS2) quantum yield, and in vivo O2 evolution. UV-B exposure induced maximum damage to the photosynthetic apparatus during senescence phase of development. The
damages were partially alleviated when UV-B exposure was accompanied by PAR. UV-B induced an enhancement in accumulation of
flavonoids during all phases of development while it caused a decline in anthocyanin content during senescence. The differential
changes in these parameters demonstrated the adaptation ability of leaves to UV-B stress during all phases of development
and the ability was modified in UV-B+ PAR exposed samples. 相似文献
2.
Pepper (Capsicum annuum L.) plants were sprayed with salicylic acid (SA) and treated with ultraviolet radiation UV-A (320–390 nm), UV-B (312 nm),
and UV-C (254 nm) of 6.1, 5.8, and 5.7 W m−2, respectively. UV significantly reduced contents of chlorophyll (Chl) a and b, and carotenoids (Car). SA treatment moderated Chl and Car reduction in plants treated with UV-B and UV-C. The quantity of
antocyanins, flavonoids, rutin, and UV-absorbing compounds in plants that were treated with UV-B, UV-C, and SA were significantly
increased. Foliar spray of SA counteracted the UV effects on pepper. 相似文献
3.
The effects of different wavebands of UV radiation on photosynthesis and the expression and abundance of photosynthetic proteins
in oilseed rape (Brassica napus L. cv. Rebel) were investigated. Plants were grown outdoors under natural radiation (52° N, 0° E) supplemented with six wavebands
of UV radiation (0.4 Wm−2) between 313 nm and 356 nm. A control treatment was centred at 343 nm. Exposure to supplementary UV-A radiation (320–400
nm) had no significant effects, however UV-B radiation, centred at 313 nm, caused a marked reduction in photosynthesis. This
decrease was related to a reduction in the initial carboxylation velocity of Rubisco which was further correlated with a large
reduction in the expression and abundance of both large and small subunits of Rubisco. These results indicate a molecular
mechanism behind UV-B induced reductions in photosynthesis per unit area in plants grown under field conditions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
The impacts of solar UV (280–400 nm) radiation on photosynthetic activities and polypeptide composition of thylakoids of cluster
bean (Cyamopsis tetragonoloba L, UV-B sensitive) and black gram (Vigna mungo L., UV-B resistant) plants were compared. The activity of photosystem 1 and especially photosystem 2 increased in cluster
bean while decreased in black gram, when either UV-B or UV-B + UV-A radiation was removed as compared to control plants. Exclusion
of UV-B radiation caused changes in the protein composition of the thylakoids particularly in the 33, 23 and 17 kDa proteins
of photosystem 2. 相似文献
5.
Guruprasad K Kadur G Bhattacharjee S Swapan B Kataria S Sunita K Yadav S Sanjeev Y Tiwari A Arjun T Baroniya S Sanjay B Rajiv A Abhinav R Mohanty P 《Photosynthesis research》2007,94(2-3):299-306
Exclusion of UV (280–380 nm) radiation from the solar spectrum can be an important tool to assess the impact of ambient UV
radiation on plant growth and performance of crop plants. The effect of exclusion of UV-B and UV-A from solar radiation on
the growth and photosynthetic components in soybean (Glycine max) leaves were investigated. Exclusion of solar UV-B and UV-B/A radiation, enhanced the fresh weight, dry weight, leaf area
as well as induced a dramatic increase in plant height, which reflected a net increase in biomass. Dry weight increase per
unit leaf area was quite significant upon both UV-B and UV-B/A exclusion from the solar spectrum. However, no changes in chlorophyll
a and b contents were observed by exclusion of solar UV radiation but the content of carotenoids was significantly (34–46%) lowered.
Analysis of chlorophyll (Chl) fluorescence transient parameters of leaf segments suggested no change in the F
v/F
m value due to UV-B or UV-B/A exclusion. Only a small reduction in photo-oxidized signal I (P700+)/unit Chl was noted. Interestingly the total soluble protein content per unit leaf area increased by 18% in UV-B/A and 40%
in UV-B excluded samples, suggesting a unique upregulation of biosynthesis and accumulation of biomass. Solar UV radiation
thus seems to primarily affect the photomorphogenic regulatory system that leads to an enhanced growth of leaves and an enhanced
rate of net photosynthesis in soybean, a crop plant of economic importance. The presence of ultra-violet components in sunlight
seems to arrest carbon sequestration in plants.
An erratum to this article can be found at 相似文献
6.
During the last few decades many experiments have been performed to evaluate the responses of plants to enhanced solar UV-B radiation (280–320 nm) that may occur because of stratospheric ozone depletion; most of them were performed in controlled environment conditions where plants were exposed to low photosynthetically active radiation (PAR) levels and high UV-B irradiance. Since environmental radiative regimes can play a role in the response of plants to UV-B enhancement, it appears doubtful whether it is valid to extrapolate the results from these experiments to plants grown in natural conditions. The objective of this work was to evaluate the effects on physiology and morphology of a bean (Phaseolus vulgaris L.) cultivar Nano Bobis, exposed to supplemental UV radiation in the open-air. UV-B radiation was supplied by fluorescent lamps to simulate a 20% stratospheric ozone reduction. Three groups of plants were grown: control (no supplemental UV), UV-A treatment (supplementation in the UV-A band) and UV-B treatment (supplemental UV-B and UV-A radiation). Each group was replicated three times. After 33 days of treatment plants grown under UV-B treatment had lower biomass, leaf area and reduced leaf elongation compared to UV-A treatment. No significant differences were detected in photosynthetic parameters, photosynthetic pigments and UV-B absorbing compounds among the three groups of plants. However, plants exposed to UV-A treatment showed a sort of 'stimulation' of their growth when compared to the control. The results of this experiment showed that plants may be sensitive to UV-A radiation, thus it is difficult to evaluate the specific effects of UV-B (280–320 nm) radiation from fluorescent lamps and it is important to choose the appropriate control. Environmental conditions strongly affect plant response to UV radiation so further field studies are necessary to assess the interaction between UV-B exposure and meteorological variability. 相似文献
7.
Swapnil Chouhan Kanchan Chauhan Sunita Kataria Guruprasad KN 《Journal of Plant Biology》2008,51(2):132-138
The impact of exclusion of solar UV-B (280–320 nm) and UV-A+B (280–400 nm) radiation on the root nodules was studied in soybean(Glycine max var. MACS 330). Soybean plants were grown in the tropical region of Indore (Latitude-22.4°N), India under field conditions
in metal cages covered with polyester exclusion filters that specifically cut off UV-B (<320 nm) and UV-A+B (<400 nm) radiation;
control plants were grown under ambient solar radiation. Leghemoglobin content was analyzed in the root nodules on the 50th day after emergence of seedlings. Exclusion of UV radiations significantly enhanced the leghemoglobin content in the nodules
on fresh weight basis; 25% and 45% higher amount of leghemoglobin were present in the nodules after the exclusion of UV-B
and UV-A+B radiation respectively. Analysis by native and SDS-PAGE showed high intense bands of leghemoglobin after the exclusion
of UV-A+B as compared to control. Exclusion of UV radiation also enhanced the growth of roots as well as aerial parts of the
plants. UV Exclusion increased nodulation by increase in the number and size of nodules. The results are discussed in the
light of advantage of exclusion for enhancing protein/nitrogen content in the plants. 相似文献
8.
Microcoleus chthonoplastes constitutes one of the dominant microorganisms in intertidal microbial mat communities. In the laboratory, the effects of
repeated daily exposure to ultraviolet radiation (16:8 light:dark cycle) was investigated in unicyanobacterial cultures isolated
from three different localities (Baltic Sea = WW6; North Sea = STO and Brittany = BRE). Photosynthesis and growth were measured
in time series (12–15 days) while UV-absorbing mycosporine-like amino acids (MAAs) and cellular integrity were determined
after 12 and 3 days exposure to three radiation treatments [PAR (22 μmol photon m−2 s−1) = P; PAR + UV-A (8 W m−2) = PA; PAR + UV-A + UV-B (0.4 W m−2) = PAB]. Isolate-specific responses to UVR were observed. The proximate response to radiation stress after 1-day treatment
showed that isolate WW6 was the most sensitive to UVR. However, repeated exposure to radiation stress indicated that photosynthetic
efficiency (F
v/F
m) of WW6 acclimated to UVR. Conversely, although photosynthesis in STO exhibited lower reduction in F
v/F
m during the first day, the values declined over time. The BRE isolate was the most tolerant to radiation stress with the lowest
reduction in F
v/F
m sustained over time. While photosynthetic efficiencies of different isolates were able to acclimate to UVR, growth did not.
The discrepancy seems to be due to the higher cell density used for photosynthesis compared to the growth measurement. Apparently,
the cell density used for photosynthesis was not high enough to offer self-shading protection because cellular damage was
also observed in those filaments under UVR. Most likely, the UVR acclimation of photosynthesis reflects predominantly the
performance of the surviving cells within the filaments. Different strategies were observed in MAAs synthesis. Total MAAs
content in WW6 was not significantly different between all the radiation treatments. In contrast, the additional fluence of
UV-A and UV-B significantly increased MAAs synthesis and accumulation in STO while only UV-B fluence significantly increased
MAAs content in BRE. Regardless of the dynamic photosynthetic recovery process and potential UV-protective functions of MAAs,
cellular investigation showed that UV-B significantly contributed to an increased cell mortality in single filaments. In their
natural mat habitat, M. chthonoplastes benefits from closely associated cyanobacteria which are highly UVR-tolerant due to the production of the extracellular UV-sunscreen
scytonemin. 相似文献
9.
The influence of ultraviolet-B radiation on the growth, pigment production and chlorophyll fluorescence of Norway spruce seedlings 总被引:3,自引:0,他引:3
Norway spruce (Picea abies (L.)Karst.) from seven seed sources was grown in a greenhouse with 8.3 and 14.7 kJ·m−2·d−1 m UV-BBE (biologically effective UV-B: 280–320 nm) irradiation, and with no supplemental irradiation as control. The seedlings total
biomass (dry weight) and shoot growth decreased with high UV-B treatment but spruce from low elevation seed sources were more
affected. The seedlings grown at the highest UV-B irradiance (14.7 kJ·m−2·d−1) showed from 5 to 38% inhibition of total biomass and 15 to 70 % shoot growth inhibition. Norway spruce populations from
higher altitude seed sources manifested greater tolerance to UV-B radiation compared to plants from low altitudes. Changes
in phospholipids and protective pigments were also determined. The plants grown at the lower UV-B irradiance (8.3 kJ·m−2·d−1) showed greater ability to concentrations UV-B-absorbing pigments then control plants. Chlorophyll a fluorescence parameter
Rfd, (Rfd=(Fm-Fs)/Fs) showed a significant decrease in needles of UV-B treated plants and this correlated with the altitude of seed source. Exposure
to UV-B affect levels of the ratio of variable to maximum fluorescence (Fv/Fm). Results from this study suggest that the response to increased levels of UV-B radiation is depended upon the ecotypic differentiation
of Norway spruce and involved changes in metabolites in plant tissues. 相似文献
10.
Role of salicylic acid in regulating ultraviolet radiation-induced oxidative stress in pepper leaves
The effect of salicylic acid (SA) counteracting the UV-A, UV-B, and UV-C-induced action on pepper (Capsicum annuum L.) plants was studied. For this purpose, the activities of antioxidant enzymes (peroxidase, polyphenol oxidase, ascorbate peroxidase, catalase, and glutathione reductase) were measured. Plants were sprayed with SA and treated with UV-A (320–390 nm), UV-B (312 nm), and UV-C (254 nm) radiation with a density of 6.1, 5.8, and 5.7 W/m2. The activities of antioxidant enzymes were enhanced in leaves in response to UV-B and UV-C radiation. SA treatment moderated an increase in the activities of some antioxidant enzymes (peroxidase, ascorbate peroxidase, catalase, and glutathione reductase) in plants that were treated with UV radiation. The activity of antioxidant enzyme polyphenol oxidase in plants that were treated with UV-B, UV-C, and SA was significantly increased. The aim of the present study was to investigate the possible protective effect of SA treatment on UV-A, UV-B, and UV-C stress. 相似文献
11.
Grifoni D Carreras G Zipoli G Sabatini F Dalla Marta A Orlandini S 《International journal of biometeorology》2008,52(8):755-763
Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological
processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines
(Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the
exposure to UV-B radiation (280–320 nm) can affect plant–disease interaction by influencing the behaviour of both pathogen
and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically
active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280–400 nm),
spectral UV-B and UV-A (320–400 nm), the biological effective UVBE, as well as the PAR (400–700 nm) component, were all considered.
The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of
row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance
at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants
received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect
on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component
was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential
consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio
was significantly lower on the plant portions exposed to full sunlight than on those in the shade. 相似文献
12.
Balakumar T. Sathiameena K. Selvakumar V. Ilanchezhian C. Murugu Paliwal K. 《Photosynthetica》1999,37(3):469-475
Cowpea [Vigna unguiculata (L.) Walp. cv. Co 4] seedlings were subjected to a weighted irradiance of 3.2 W m-2 s-1 of biologically effective ultraviolet-B radiation (UV-B, 280–320 nm) and the changes in the kinetic and other characteristics
of nitrite reductase (NiR) were recorded. The activity of NiR was hampered by 19 % under UV-B irradiation compared to the
control. The UV-B treated plants required higher concentrations of nitrate for the induction of NiR synthesis than the controls.
The NiR activity decay kinetics showed that the UV-B treatment significantly lowers the t1/2 of the enzyme, thereby indicating a reduced rate of enzyme turnover. The comparison of kinetic characteristics of nitrate
reductase (NR) and NiR under UV-B treatment showed that NiR was not so sensitive to UV-B radiation as NR. As shown by enzyme
turnover rates, NiR extracted from plants irradiated by UV-B in situ was less sensitive to UV-B radiation than the enzyme extract subjected to in vitro UV-B irradiation. Though NiR was less damaged by UV-B treatment than NR, subtle changes occurred in its kinetic characteristics.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
Acclimation of brown algal photosynthesis to ultraviolet radiation in Arctic coastal waters (Spitsbergen, Norway) 总被引:9,自引:2,他引:7
Kai Bischof Dieter Hanelt Helmut Tüg Ulf Karsten Patty E. M. Brouwer Christian Wiencke 《Polar Biology》1998,20(6):388-395
In field studies conducted at the Kongsfjord (Spitsbergen) changes of the irradiance in the atmosphere and the sublittoral
zone were monitored from the beginning of June until the end of August 1997, to register the minimum and maximum fluxes of
ultraviolet and photosynthetically active radiation and to characterise the underwater light climate. Measurements of photosynthesis
in three abundant brown algal species (Alaria esculenta, Laminaria saccharina, Saccorhiza dermatodea) were conducted to test whether their photosynthetic performance reflects changing light climate in accordance with depth.
Plants sampled at various depths were exposed to controlled fluence rates of photosynthetically active radiation (400–700 nm),
UV-A (320–400 nm) and UV-B (280–320 nm). Changes in photosynthetic performance during the treatments were monitored by measuring
variable chlorophyll fluorescence of photosystem II. In each species, the degree of inhibition of photosynthesis was related
to the original collection depth, i.e. shallow-water isolates were more resistant than plants from deeper waters. The results
show that macroalgae acclimate effectively to increasing irradiance levels for both photosynthetically active and ultraviolet
radiation. However, the kinetics of acclimation are different within the different species. It is shown that one important
strategy to cope with higher irradiance levels in shallow waters is the capability for a faster recovery from high light stress
compared to isolates from deeper waters.
Received: 13 March 1998 / Accepted: 16 May 1998 相似文献
14.
At Helgoland, in the North Sea, growth of the high sublittoral brown macroalga Dictyota dichotoma (Hudson) Lamoroux was examined in October (the time of tetraspore release) in an outdoor tank by exposing 2-day-old germlings
to four solar radiation treatments achieved with different filter materials or an additional artificial light source: photosynthetically
active radiation (PAR; 395–700 nm), PAR plus ultraviolet (UV)-A (320–700 nm), full solar spectrum, or solar spectrum plus
artificial UV radiation (UVR). Based on length measurements over a period of 3 weeks, the growth rate in germlings strongly
decreased in conditions with UVR compared to PAR: by 14% under PAR+UV-A, by 31% under the full solar spectrum and by 65% with
additional UVR. Although growth rates of germlings under UVR were reduced mainly in the first week, the plants did not regain
the size of the untreated plants even after 9 weeks. Regardless of the exposure, no defects in morphology or anatomy including
the exposed apical meristem were detected, except for a reduction in cell division rates perhaps due to additional cost for
photoprotective or repair mechanisms. Depending on the actual position of D. dichotoma plants in the natural habitat, individuals in high positions receive substantial amounts of the more harmful UV-B while those
lower down might only receive UV-A during part of the day, thus the effect of UV-B on the growth of D. dichotoma will depend on its position in the field. The effects of tidal variation of the light climate and the implications of our
results for the zonation of D. dichotoma are discussed.
Received in revised form: 6 July 2000
Electronic Publication 相似文献
15.
UV-B and cadmium, alone and together, induced changes in photosynthetic pigment levels, photosynthetic electron transport
activity, enzymatic and non-enzymatic (low molecular weight) antioxidants, level of hydrogen peroxide and lipid peroxidation
in Riccia sp. were evaluated. Chlorophyll content was found to decrease with the rising concentration of cadmium and UV-B exposure
alone and its level further declined when both the stresses were applied together. In contrast to this, carotenoids exhibited
varied response, as it showed enhancement with UV-B (15, 30 and 45 min exposure) and low concentration of Cd (1 and 10 μM)
treatment alone and in combination. Both the stresses caused strong inhibitory effect on PS II activity (H2O → p-BQ), while PS I activity (DCPIP/ASC → MV) appeared to be less sensitive. Total peroxide content increased with simultaneous
increase in lipid peroxidation. The level of non-enzymatic antioxidant ascorbate and enzymatic antioxidants superoxide dismutase
and peroxidase activity were found to increase with simultaneous decrease in catalase activity following UV-B and Cd treatments.
These results indicate that 45 min of UV-B exposure and 10, 100 and 1000 μM cadmium alone and together, strongly arrested
electron flow through PS II which caused accelerated generation of reactive oxygen species (H2O2) and excess accumulation of H2O2 due to significant inhibition of catalase activity, led to the oxidative damage in Riccia sp. 相似文献
16.
Variation of chromophoric dissolved organic matter and possible attenuation depth of ultraviolet radiation in Yunnan Plateau lakes 总被引:2,自引:0,他引:2
The increase of ultraviolet radiation (UVR, 280–400 nm) caused by stratospheric ozone depletion has profound effects on aquatic
ecosystems. High-altitude lakes in the Yunnan Plateau are exposed to high intensities of UVR and contain low concentrations
of chromophoric dissolved organic matter (CDOM). Thirty-eight lakes in the Yunnan Plateau with elevations from 1291 to 3809
m above sea level were investigated to study CDOM concentrations and possible effects of UVR on the lake ecosystem. The attenuation
of UVR in the Yunnan Plateau lakes was calculated from the absorption coefficient of CDOM based on an empirical relationship
from lakes in the Alps and Pyrenees mountains. Absorption coefficients [α(λ)] at 320 nm [α(320)] ranged from 0.52 to 14.05 m−1 (mean ± standard deviation, 4.40 ± 3.85 m−1) and at 380 nm [α(380)] from 0.05 to 4.51 m−1 (1.40 ± 1.30 m−1). The exponential slope coefficient for the relationship of wavelength to α(λ) ranged from 16.2 to 41.4 μm−1 (21.74 ± 4.93 μm−1) over the 280–400 nm interval. Normalized fluorescence emission (NFLU) at 450 nm from an excitation wavelength of 355 nm,
F
n(355), averaged 7.93 ± 3.22 NFLU. A significant positive relationship was found between α(355) and F
n(355). The estimated diffuse attenuation coefficients of UV-B (320 nm) and UV-A (380 nm) ranged from 0.55 to 15.77 m−1 and from 0.24 to 6.73 m−1; the corresponding 1% attenuation depths ranged from 0.29 to 8.44 m and from 0.68 to 19.12 m. Twenty-five of 38 lakes had
1% UV-B attenuation depths of 1.5 m or more. The median 1% attenuation depth was 28.8% of the sampling depth for UV-B radiation
and 60% for UV-A. In addition to CDOM, chlorophyll α (Chla) and total suspended matter (TSM) also may contribute to attenuation of UVR. 相似文献
17.
E. Walter Helbling M. Eugenia Farías M. Verónica Fernández Zenoff Virginia E. Villafañe 《Hydrobiologia》2006,559(1):123-134
In situ experiments were conducted at various depths in the water column to determine the effects of solar ultraviolet radiation
(UVR, 280–400 nm) on photosynthesis of natural phytoplankton assemblages from the subtropical Lake La Angostura (Argentina,
26°45′ S; 65°37° W, 1980 m asl.). Water samples were taken daily and incubated under three radiation treatments: (a) Samples
exposed to UVR + Photosynthetic Available Radiation (PAR) – PAB treatment (280–700 nm); (b) Samples exposed to ultraviolet-A
radiation (UV-A) + PAR – PA treatment (320–700 nm), and, (c) Samples exposed to PAR only – P treatment (400–700 nm). Additionally,
depth profiles were done to determine different physical (i.e., temperature and underwater radiation field) and biological
characteristics of the water column – photosynthetic pigments, UV-absorbing compounds, cell concentration, deoxyribonucleic
acid (DNA) and cyclobutane pyrimidine dimers (CPDs). The effects of UVR on natural phytoplankton assemblages were significant
only in the first 50 cm of the water column, causing a decrease in photosynthetic rates of 36 and 20% due to UV-A and ultraviolet-B
radiation (UV-B), respectively; below this depth, however, there were no significant differences between radiation treatments.
Concentration of CPDs per mega base of DNA in natural phytoplankton was low, <27 CPDs MB−1 between 0 and 4 m. Data on net DNA damage, together with that on mixing conditions of the water column, suggest that mixing
can favour phytoplankton by allowing cells to be transported to depths where active repair can take place. This mechanism
to reduce UVR-induced DNA damage would be of great advantage for these assemblages dominated by small cyanobacteria and chlorophytes
where UV-absorbing compounds that could act as sunscreens are virtually absent. 相似文献
18.
The effects of enhanced UV-B radiation on growth and photosynthetic activities were investigated in fronds of the aquatic fern Azolla microphylla Kaulf. The fronds were exposed to UV-B radiation intermittently once in 3 d during 12 d. Biomass and relative growth rate of UV-B treated Azolla plants and the heterocyst frequency of the UV-B treated symbiont decreased resulting in an increase in doubling time over the control. The doubling time was 3.08 d for control and 3.35 d for UV-B irradiated plants. Chl and carotenoid contents per unit fresh mass and photosystem 2 (PS2) activity also decreased under UV-B treatment. Measurements of photosynthetic activity in terms of fluorescence kinetics and PS2 mediated O2 evolution showed that the aquatic fern Azolla is sensitive to UV-B damage. 相似文献
19.
Growth patterns and nitrogen economy were studied in pot-grown seedlings of mountain birch subjected to different ultraviolet
radiation under both laboratory and outdoor conditions at Abisko in northern Sweden. In the laboratory, nutrient supply, temperature,
humidity, ultraviolet radiation-A (UV-A, 320–400 nm) and B (UV-B, 280–320 nm) were controlled, while photosynthetically active
radiation (PAR, 400–700 nm) and photoperiod varied naturally. Under outdoor conditions nutrient supply was controlled, and
the irradiation treatments were ambient and above-ambient UV-B using additional fluorescent lamps. Mountain birch nitrogen
economy was affected by increased ultraviolet radiation, as reflected by a changed relationship between plant growth and plant
nitrogen both in the laboratory and outdoors. In the laboratory enhanced UV-A decreased leaf area per unit plant biomass (leaf
area ratio) but increased biomass productivity, both per unit leaf area (leaf area productivity) and per unit leaf nitrogen
(leaf nitrogen productivity). Low levels of UV-B affected growth patterns and nitrogen economy in a similar way to enhanced
UV-A. High levels of UV-B clearly decreased relative growth rate and nitrogen productivity, as leaf area ratio, leaf area
productivity and leaf nitrogen productivity were all decreased. Under outdoor conditions above-ambient levels of UV-B did
not alter growth or biomass allocation traits of the seedlings, whilst nitrogen productivity was increased. Mountain birch
seedlings originating from different mother trees varied significantly in their responses to different ultraviolet radiation.
Received: 10 April 1997 / Accepted: 19 September 1997 相似文献
20.
Spectral balance and UV-B sensitivity of soybean: a field experiment 总被引:12,自引:5,他引:7
Soybean [Glycine max (L.) Merr.] cultivar Essex was grown and tested for sensitivity to UV-B radiation (280–320 nm) under different combinations of UV-A (320–400 nm) and PFD (400–700 nm) radiation in four simultaneous field experiments. The radiation conditions were effected with combinations of filtered solar radiation and UV-B and UV-A lamps electronically modulated to track ambient radiation. Significant UV-B-caused decreases in total aboveground production and growth were seen only when PFD and UV-A were reduced to less than half their flux in sunlight. When PFD was low, UV-A appeared to be particularly effective in mitigating UV-B damage. However, when PFD was high, substantial UV-A did not appear to be required for UV-B damage mitigation. Leaf chlorophyll fluorescence did not indicate photosynthetic damage under any radiation combination. With UV-B, leaves in all experiments exhibited increased UV-absorbing pigments and decreased whole-leaf UV transmittance. Results of these field experiments indicate difficulties in extrapolating from UV-B experiments conducted in glasshouse or growth cabinet conditions to plant UV-B sensitivity in the field. Implications for UV radiation weighting functions in evaluating atmospheric ozone reduction are also raised. 相似文献