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1.
Net photosynthetic rate, radiation use efficiency, chlorophyll (Chl) fluorescence, photochemical reflectance index (PRI), and leaf water potential were measured during a 25-d period of progressive water deficit in quinoa plants grown in a glasshouse in order to examine effects of water stress and ontogeny. All physiological parameters except Fv/Fm were sensitive to water stress. Ontogenic variations did not exist in Fv/Fm and leaf water potential, and were moderate to high in the other parameters. The complete recovery of photosynthetic parameters after re-irrigation was related with the stability in Fv/Fm. PRI showed significant correlation with predawn leaf water potential, Fm, and midday Fv/Fm. Thus PRI and Chl fluorescence may help in assessing physiological changes in quinoa plants across different developmental stages and water status. 相似文献
2.
光强在低温弱光胁迫后番茄叶片光合作用恢复中的作用 总被引:7,自引:0,他引:7
为了研究光强在低温弱光胁迫后番茄叶片光合作用恢复中的作用,以番茄品种浙粉202为材料,研究了低温弱光后恢复期全光照与遮荫对光合作用和叶绿素荧光参数的影响。结果表明:低温弱光(8℃/12℃,PFD 80 μmol·m-2·s-1)导致番茄叶片Pn、ΦPSⅡ、qP和Fv′/Fm′的下降,但诱导了NPQ的上升,未引起Fv/Fm的变化;全光照(100%光照)下恢复1 使得植株叶片Pn、Fv/Fm、ΦPSⅡ、qP、NPQ和Fv′/Fm′均大幅下降,随后光合和荧光参数可缓慢恢复至对照水平;遮荫(40%光照)恢复植株Fv/Fm、ΦPSⅡ和Fv′/Fm′仅在第一天稍有下降,而Pn和qP还略有上升,NPQ虽有所降低但仍显著高于对照水平,随后光合和荧光参数均可迅速恢复到对照水平。说明低温弱光虽抑制了光合作用的进行,但并未引起光抑制的发生;全光照恢复加剧了叶片光抑制的发生,而遮荫恢复可通过叶片PSⅡ光化学活性的快速恢复和天线色素热耗散能力的增强以保护光合机构免受伤害,有利于光合作用的迅速恢复。 相似文献
3.
以砂培菊芋(Helianthus tuberosus)幼苗作为试验材料,分别进行不同浓度NaCl (50、 100、150、200、250 mmol&;#8226;L-1)和Na2CO3 (25、50、 75、100、125 mmol&;#8226;L-1)胁迫处理,以1/2全营养液作为对照,处理7 d后研究NaCl和Na2CO3胁迫处理对菊芋幼苗叶片光合作用及叶绿素动力学 参数的影响。结果表明:1)在NaCl处理下,当浓度小于150 mmol&;#8226;L-1时,增加了菊芋的叶绿素含量、净光合速率(Net photosynthetic rate, Pn)和气孔导度(Stomatal conductivity, Gs),对荧光参数PSⅡ的电子传递情况( Fm/Fo)、PSⅡ原初光能转换效率(Fv/Fm)、PSⅡ量子效率 (Actual quantum yield of PSⅡ under actinic irradiation,φPSⅡ)和光化学猝灭系数(Photochemical quenching coefficient, qP)和非 光化学猝灭系 数(Non-photochemical quenching coefficient, NPQ)没有显著影响,随着浓度的增加,各项生理指标与对照相比除了NPQ显著 增加,其余均显著降低;2)在Na2CO3胁迫处理下,随着Na2CO3浓度的增加,与对照相比菊芋幼苗叶绿素含量、Pn、Gs以及叶绿素a荧光诱导动力 学参数Fm/Fo、Fv/Fm、φPSⅡ和qP均显著降低,NPQ显著增加;3)就NaCl和Na2CO3相比而言,在相同Na+浓度情况下,处于Na2CO3胁迫下的菊芋 幼苗的叶绿素含量、Pn、Gs以及叶绿素a荧光诱导动力学参数Fm/Fo、Fv/Fm、φPSⅡ和qP下降幅度和NPQ的增加幅度均显著大于NaCl,这说明 NaCl和Na2CO3胁迫均对菊芋幼苗造成不同程度的伤害,但在相同Na+浓度情况下,Na2CO3的伤害程度大于NaCl。由此说明菊芋对盐的忍耐程度高 于碱。 相似文献
4.
T. Lundmark Johan Bergh Martin Strand Andres Koppel 《Trees - Structure and Function》1998,13(2):63-67
The seasonal variation in maximum photochemical efficiency of photosystem II (Fv/Fm) and the relationship between Fv/Fm and climatic factors such as irradiance, frost-nights and daily mean temperature was studied in young Norway spruce trees
for 4 years in northern Sweden. As a result of night frost, the Fv/Fm-ratio gradually decreased during the autumn. There was between-year variation in the pattern of Fv/Fm in fully exposed shoots during autumn and spring, largely as an effect of differing temperature conditions. During spring,
there was a strong apparent relationship between daily mean temperature and Fv/Fm within the temperature range –3 to 12°C. The light regime to which the needles were exposed during winter affected Fv/Fm, and moderately shaded shoots from the bottom of the canopy generally had a higher Fv/Fm-ratio than fully exposed shoots from the top of the canopy.
Received: 1 October 1997 / Accepted: 16 June 1998 相似文献
5.
A. Mena-Petite A. Robredo S. Alcalde M. Duñabeitia M. González-Moro M. Lacuesta A. Muñoz-Rueda 《Trees - Structure and Function》2003,17(2):133-143
Post-storage gas exchange parameters like CO2 assimilation, stomatal conductance, transpiration, water use efficiency and intercellular CO2 concentrations, together with several chlorophyll a fluorescence parameters: Fo, Fv, Fv/Fm, Fm/Fo and Fv/Fo were examined in radiata pine (Pinus radiata D. Don) seedlings that were stored for 1, 8 or 15 days at 4° or 10°C with or without soil around the roots. Results were analysed in relation to post-storage water potential and electrolyte leakage in order to forecast their vitality (root growth potential) following cold storage, and post-planting survival potential under optimal conditions. During storage at 4° and 10°C, photosynthesis was reduced, being more pronounced in bare-root seedlings than in seedlings with soil around the roots. The depletion of CO2 assimilation seemed not to be solely a stomatal effect as effects on chloroplasts contributed to this photosynthetic inhibition. Thus, the fall in the ratios Fv/Fm, Fv/Fo and Fm/Fo indicated photochemical apparatus damage during storage. Photosynthetic rate was positively correlated with the root growth index and new root length showing that new root growth is dependent primarily on current photosynthesis. Pre-planting exposure of bare-root radiata pine seedlings to temperatures of 10°C for more than 24 h during transportation or storage is not recommended. 相似文献
6.
Photosynthetic rates of green leaves (GL) and green flower petals (GFP) of the CAM plant Dendrobium cv. Burana Jade and their sensitivities to different growth irradiances were studied in shade-grown plants over a period
of 4 weeks. Maximal photosynthetic O2 evolution rates and CAM acidities [dawn/dusk fluctuations in titratable acidity] were higher in leaves exposed to intermediate
sunlight [a maximal photosynthetic photon flux density (PPFD) of 500–600 μmol m−2 s−1] than in leaves grown under full sunlight (a maximal PPFD of 1 000–1 200 μmol m−2 s−1) and shade (a maximal PPFD of 200–250 μmol m−2 s−1). However, these two parameters of GFP were highest in plants grown under the shade and lowest in full sun-grown plants.
Both GL and GFP of plants exposed to full sunlight had lower predawn Fv/Fm [dark adapted ratio of variable to maximal fluorescence (the maximal photosystem 2 yield without actinic irradiation)] than
those of shade-grown plants. When exposed to intermediate sunlight, however, there were no significant changes in predawn
Fv/Fm in GL whereas a significant decrease in predawn Fv/Fm was found in GFP of the same plant. GFP exposed to full sunlight exhibited a greater decrease in predawn Fv/Fm compared to those exposed to intermediate sunlight. The patterns of changes in total chlorophyll (Chl) content of GL and
GFP were similar to those of Fv/Fm. Although midday Fv/Fm fluctuated with prevailing irradiance, changes of midday Fv/Fm after exposure to different growth irradiances were similar to those of predawn Fv/Fm in both GL and GFP. The decreases in predawn and midday Fv/Fm were much more pronounced in GFP than in GL under full sunlight, indicating greater sensitivity in GFP to high irradiance
(HI). In the laboratory, electron transport rate and photochemical and non-photochemical quenching of Chl fluorescence were
also determined under different irradiances. All results indicated that GFP are more susceptible to HI than GL. Although the
GFP of Dendrobium cv. Burana Jade require a lower amount of radiant energy for photosynthesis and this plant is usually grown in the shade,
is not necessarily a shade plant. 相似文献
7.
Temperature dependence of UV radiation effects in Arctic and temperate isolates of three red macrophytes 总被引:1,自引:0,他引:1
The temperature dependence of UV effects was studied for Arctic and temperate isolates of the red macrophytes Palmaria palmata, Coccotylus truncatus and Phycodrys rubens. The effects of daily repeated artificial ultraviolet B and A radiation (UVBR: 280–320?nm, UVAR: 320–400?nm) treatments were examined for all isolates at 6, 12 and 18?°C by measuring growth, optimal quantum yield of PSII (Fv/Fm) and cyclobutane-pyrimidine dimer (CPD) accumulation. Furthermore, possible ecotypic differences in UV sensitivity between Arctic and temperate isolates were evaluated. Large species-specific differences in UV sensitivity were observed for all parameters: the lower subtidal species C. truncatus and P. rubens were highly sensitive to the UV treatments, whereas P. palmata, which predominantly occurs in the upper subtidal zone, was not affected by these treatments. Only minor differences were found between Arctic and temperate isolates, suggesting that no differences in UV sensitivity have evolved in these species. Relative growth rates were temperature-dependent, whereas species-specific UV effects on growth rates were relatively independent of temperature. In contrast, the species-specific decrease in Fv/Fm and its subsequent recovery were temperature-dependent in all species. UV effects on Fv/Fm were lower at 12 and 18?°C compared with 6?°C. In addition, UV effects on Fv/Fm decreased in the course of the experiment at all temperatures, indicating acclimation to the UV treatments. CPDs accumulated during the experiment in both isolates of P. rubens, whereas CPD concentrations remained low for the other two species. CPD accumulation appeared to be independent of temperature. The results suggest that summer temperatures occurring in temperate regions facilitate repair of UV-induced damage and acclimation to UV radiation in these algae compared with Arctic temperatures. Because the differences in UV effects on Fv/Fm, growth and CPD accumulation were relatively small over a broad range of temperatures, it was concluded that the influence of temperature on UV effects is small in these species. 相似文献
8.
孟庆焕;祖元刚;郭晓瑞;段喜华 《植物研究》2013,33(2):181-185
在增强UV-B辐射下,以3年生兴安落叶松幼苗为实验材料,研究了外源NO供体硝普钠(Sodium nitroprusside,SNP)对幼苗的光合色素(Chla、Chlb和Car)和叶绿素荧光参数的影响。方差分析结果表明0.5 mmol·L-1的SNP对增补UV B胁迫下的兴安落叶松幼苗产生显著影响。0.5 mmol·L-1的SNP能够显著抑制增补UV-B辐射后光合色素、Fv/Fm、ΦPSⅡ、Fv′/Fm′和qP的明显下降以及Chla /Chlb、Fo和NPQ的升高。表明了外源NO能够减轻UV-B辐射胁迫下兴安落叶松幼苗光合反应中心的生理损伤,从而增强兴安落叶松幼苗对增补UV-B辐射胁迫环境的适应能力。 相似文献
9.
氯化钠胁迫对枳椇和皂荚生长、叶绿素荧光及活性氧代谢的影响 总被引:10,自引:0,他引:10
以盆栽枳椇和皂荚为试材,研究了不同浓度NaCl处理(CK、0.15%、0.30%、0.45%、0.60%)对枳椇和皂荚植株生长、叶绿素荧光特性和活性氧代谢的影响.结果表明:随着NaCl浓度的提高,植株生长量、叶片叶绿素含量、Fv/Fm、ΦPSⅡ、qP均逐渐下降,而qN逐渐升高.0.15% NaCl胁迫10 d后,枳椇叶片叶绿素含量、Fv/Fm、ΦPSⅡ、qP较对照处理分别降低了19.77%、2.94%、29.03%、8.16%,差异显著(P<0.05),而皂荚与对照处理差异不显著;0.30%NaCl胁迫下,皂荚Fv/Fm和ΦPSⅡ较对照处理分别降低了1.91%、14.66%,差异显著(P<0.05);0.45%NaCl胁迫下,皂荚叶片叶绿素含量和qP与对照处理差异显著(P<0.05),分别降低了29.28%和11.36%.随着NaCl浓度的增加,皂荚SOD活性持续升高,枳椇呈先升高后降低变化,在0.15% NaCl胁迫下达最大值;两种苗木细胞POD、CAT活性均呈先升后降趋势,且皂荚的升幅大于枳椇.二者的MDA含量均呈上升趋势,且枳椇的升高幅度大于皂荚,说明枳椇产生了较严重的膜脂过氧化.由此推断,皂荚的耐盐性较强与其具有较强的抗氧化保护酶系统有关. 相似文献
10.
Enhanced UV-B radiation alleviates the adverse effects of summer drought in two Mediterranean pines under field conditions 总被引:9,自引:0,他引:9
Yiola Petropoulou Aris Kyparissis Demosthenis Nikolopoulos Yiannis Manetas 《Physiologia plantarum》1995,94(1):37-44
The effects of enhanced UV-B (290-320 nm) radiation on two native Mediterranean pines (Pinus pinea L., Pinus halepensis Mill.) were recorded during a one-year field study. Plants received ambient or ambient plus supplemental UV-B radiation (simulating a 15% stratospheric ozone depletion over Patras. Greece, 38.3°N. 29.1°E) and only natural precipitation, i.e. they were simultaneously exposed to other natural stresses. particularly water stress during summer. Supplemental UV-B irradiation started in early February, 1993 and up to late June, no effects were observed on growth and photochemical efficiency of photosystem II, as measured by chlorophy II fluorescence induction. Water stress during the summer was manifested in the control plants as a decline in the ratio of variable to maximum fluorescence (Fv/Fm), the apparent photon yield for oxygen evolution (φl) and the photosynthetic capacity at 5% CO2 (Pm). In addition, a partial needle loss was evident. Under supplemental UV-B radiation, however, the decreases in Fv/Fm, φi, and Pm. as well as needle losses were significantly less. Soon after the first heavy autumn rains. photosynthetic parameters in both control and UV-B treated plants recovered to similar values. but the transient summer superiority of UV-B irradiated plants resulted in a significant increase in their dry weight measured at plant harvest. during late January. 1994. Plant height. UV-B absorbing compounds, photosynthetic pigments and relative water content measured at late spring. late summer and at plant harvest, were not significantly affected by supplemental UV-B radiation. The results indicate that enhanced UV-B radiation may be beneficial for Mediterranean pines through a partial alleviation of the adverse effects of summer drought. 相似文献
11.
高温胁迫对切花菊‘神马’光合作用与叶绿素荧光的影响 总被引:11,自引:1,他引:11
以切花菊品种‘神马’为试材,在40 ℃/35 ℃(昼/夜)与33 ℃/28 ℃高温下分别胁迫11 d,然后转入23 ℃/18 ℃恢复5 d,研究不同高温强度及恢复对菊花光合作用的影响.结果表明:33 ℃/28 ℃下净光合速率(Pn)逐渐降低,气孔导度(Gs)5 d后明显降低,两参数均可在23 ℃/18 ℃下恢复到对照的80%以上;40 ℃/35 ℃高温下Pn与Gs大幅度持续降低,胁迫前期,胞间CO2浓度(Ci)上升,Pn的降低主要由非气孔因素导致;9 d后Ci与Pn同时降低,气孔限制成为Pn 降低的主要因素.高温使菊花叶片的PSⅡ潜在活性(Fv/Fo)、最大光化效率(Fv/Fm)、实际光化效率(ΦPSⅡ)与天线转换效率 (Fv′/Fm′)降低,天线热耗散(D)增加,表明高温胁迫下菊花通过降低光能的捕获与通过PSⅡ的电子传递效率来保护反应中心免受伤害.33 ℃/28 ℃下光化学猝灭系数(qP)呈先下降后上升趋势,推测此温度下受体端电子传递首先受到抑制;40 ℃/35 ℃下qP持续增加,表明放氧复合体(OEC)可能是菊花光合系统中极端高温伤害的原初位点. 相似文献
12.
Assessment of oxidative stress in the planktonic diatom Thalassiosira pseudonana in response to UVA and UVB radiation 总被引:1,自引:0,他引:1
Induction of oxidative stress by UVA and UVB in the diatom Thalassiosirapseudonana was experimentally studied. Cells, pre-grown in alight-limited continuous culture, were incubated for 4 h at175 µmol m-2s-1photosynthetically active radiation, withoptional supplementary UVA at an unweighted dose rate of 0.70W m-2, or 2.79 W m-2UVA plus 0.45 W m-2UVB (unweighted). A fluorescence-basedmeasure of photosynthetic efficiency (Fv/Fm) decreased from0.69 to 0.58 in the presence of UVB, whereas UVA caused a minordecrease of Fv/Fm. Quantitative analysis of confocal imagesshowed a minor increase of active oxygen production associatedwith supplemental UVA alone, and a 100% increase with additionalUVB. Cellular malondialdehyde, an indicator of lipid peroxidationby active oxygen, almost doubled under UVA and increased three-foldwith additional UVB. Activities of superoxide dismutase (scavengingactive oxygen) and glutathione reductase (reducing GSSG to GSH)increased in response to UVB exposure, whereas ascorbate peroxidaseactivities did not. UVB caused a minor decrease in the glutathioneratio GSH : (GSH + 0.5GSSG), which indicates a moderate oxidativestress. 相似文献
13.
为了研究水杨酸(SA)对高温强光胁迫下小麦叶片类囊体膜D1蛋白磷酸化和PSⅡ功能的影响,用0.5 mmol·L-1 SA溶液预处理灌浆期小麦叶片,以水预处理为对照,然后将预处理植株进行高温强光(35 ℃,1 600 μmol·m-2·s-1)处理,测定胁迫处理过程中小麦旗叶光合电子传递速率、净光合速率、叶绿素荧光参数及D1蛋白的变化.结果表明:SA预处理有效抑制了高温强光下D1蛋白的净降解,保持了较高的D1蛋白磷酸化水平、全链电子传递速率和PSⅡ电子传递速率,维持了较高的PSⅡ原初光化学效率(Fv/Fm)、实际光化学效率(ФPSⅡ)、光化学淬灭系数(qP)和净光合速率(Pn).表明外源SA通过调节小麦叶绿体D1蛋白的周转,减轻了高温强光胁迫对叶片光合机构的损伤,有利于PSⅡ的正常运转. 相似文献
14.
Schofield Oscar; Grzymski Joseph; Moline Mark M.A.; Jovine Raffael V.M. 《Journal of plankton research》1998,20(7):1241-1258
This study assessed the impact of temperature on the photosyntheticactivity in the dinoflagellate Alexandrium fundyense (Ca28)for cultures grown at 75 mol photons m2 s1 overa range of temperatures. Increasing light intensity under statictemperatures caused a 5-fold decrease in the maximum quantumyield for photosystern II (PSII) (FvlFm) Carbon fixation ratesmirrored high-light depressions in (FvlFm). Cells in the presenceof streptomycin showed an 83% recovery in (FvlFm); therefore,only a minor proportion of the decline in (FvlFm)was attributableto PSII damage by bright light. For cells transferred to highertemperatures, F. was less sensitive to high light, decreasingonly 2040% compared to the 8090% decrease observedfor cells incubated at their ambient growth temperature. Forcells shifted to higher temperatures, the rapid recovery phaseof (FvlFm) was not present; therefore, cells did not initiatedownregulation of PSII. Higher capacity to maintain electrontransport, as indicated by the quantum yields, was confirmedby enhanced carbon fixation. Shifts lower temperatures significantlyincreased PSII sensitivity to high light. Overall, these relationshipsreflect the synergy between photosynthetic light and dark reactionswhich are differentially impacted by changes in temperature. 相似文献
15.
Adult trees of Quercus petraea were submitted to controlled water shortage in a natural stand near Nancy, France. Diurnal course of net CO2 assimilation rate (A) was measured in situ together with chlorophyll a fluorescence determined on dark adapted leaves. In 1990, trees experienced a strong water stress, with predawn and midday leaf water potentials below –2·0 and –3·0 MPa, respectively. Diurnal course of A of well-watered trees exhibited sometimes important midday decreases in A related to high temperature and vapour pressure deficit. Decreases in initial (Fo) and maximal (Fm) fluorescence and sometimes in photochemical efficiency of photosystem II (Fv/Fm) were observed and probably revealed the onset of mechanisms for thermal de-excitation. These mechanisms were shown to be sensitive to dithiothreitol. All these effects were reversible and vanished almost completely overnight. Therefore, they may be considered as protective mechanisms adjusting activity of photosystem II to the electron requirement for photosynthesis. Water stress amplified these reactions: A was strongly decreased, showing important midday depression; diurnal reductions in Fm and Fv/Fm were enhanced. The same trends were observed during summer 1991, despite a less marked drought. These protective mechanisms seemed very effective, as no photoinhibitory damage to PS II could be detected in either water stressed or control trees. 相似文献
16.
Fernando Valladares José Chico Ismael Aranda Luis Balaguer Pierre Dizengremel Esteban Manrique Erwin Dreyer 《Trees - Structure and Function》2002,16(6):395-403
The responses of Quercus robur (oak) and Fagus sylvatica (beech) seedlings to four different light environments (full, 50%, 40% and 15% sunlight) and to a rapid increase in irradiance were explored during the summer, after 2 years of growth in a forest nursery at Nancy (France). Significant differences between the two species were found for most variables. Phenotypic plasticity for morphological variables (root-shoot ratio, leaf size, leaf weight ratio) was higher in beech than in oak, while the reverse was true for anatomical (stomatal density, epidermis thickness, exchange surface area of the palisade parenchyma) and physiological (maximum photosynthetic rate, stomatal conductance, Rubisco activity) variables. Predawn photochemical efficiency (Fv/Fm) was higher in oak than in beech in all light environments except in 15% sunlight. Fv/Fm was significantly lower in 100% sunlight than in the other light environments in beech but not in oak. Maximum photosynthetic rates (Amax) increased with increasing light availability in the two species but they were always higher in oak than in beech. Oak exhibited higher Rubisco activity than beech in full sunlight. The transfer of shade-adapted seedlings to the open caused a decrease of Fv/Fm, which was larger for beech than for oak. Transferred oak but not beech plants recovered gradually to the control Fv/Fm values. The decreased chlorophyll content and the increased non-photochemical quenching observed in high-light beech seedlings were not enough to avoid photoinhibition. The results suggest that a greater tolerance of strong irradiance is linked to an enhanced physiological plasticity (variables related to photosynthesis), while shade tolerance relies on an enhanced plasticity in light-harvesting variables (crown morphology and chlorophyll content). 相似文献
17.
M. A. Sobrado 《Photosynthetica》2008,46(2):202-207
In six dominant species of the Amazonian ‘Bana’ vegetation, leaf blade characteristics, pigment composition, and chlorophyll (Chl) fluorescence parameters were measured in young and mature leaves under field conditions. Leaf δ13C was comparable in the six species, which suggested that both expanding and expanded leaves contained organic matter fixed under similar intercellular and ambient CO2 concentration (C i/C a). High leaf C/N and negative δ15N values found in this habitat were consistent with the extreme soil N-deficiency. Analysis of Chl and carotenoids showed that expanding leaves had an incomplete development of photosynthetic antenna when compared to adult leaves. Dynamic inactivation of photosystem 2 (PS2) at midday was observed at both leaf ages as Fv/Fm decreased compared to predawn values. Adult leaves reached overnight Fv/Fm ratios typical of healthy leaves. Overnight recovery of Fv/Fm in expanding leaves was incomplete. F0 remained unchanged from midday to predawn and Fv tended to increase from midday to predawn. The recovery from midday depression observed in adult leaves suggested an acclimatory down-regulation associated with photo-protection and non-damage of PS2. 相似文献
18.
Silicon Alleviates Drought Stress of Rice Plants by Improving Plant Water Status,Photosynthesis and Mineral Nutrient Absorption 总被引:7,自引:0,他引:7
Drought is a major constraint for rice production in the rainfed lowlands in China. Silicon (Si) has been verified to play
an important role in enhancing plant resistance to environmental stress. Two near-isogenic lines of rice (Oryza sativa L.), w-14 (drought susceptible) and w-20 (drought resistant), were selected to study the effects of exogenous Si application
on the physiological traits and nutritional status of rice under drought stress. In wet conditions, Si supply had no effects
on growth and physiological parameters of rice plants. Drought stress was found to reduce dry weight, root traits, water potential,
photosynthetic parameters, basal quantum yield (F
v/F
0), and maximum quantum efficiency of PSII photochemistry (F
v/F
m) in rice plants, while Si application significantly increased photosynthetic rate (Pr), transpiration rate (Tr), F
v/F
0, and F
v/F
m of rice plants under drought stress. In addition, water stress increased K, Na, Ca, Mg, Fe content of rice plants, but Si
treatment significantly reduced these nutrient level. These results suggested that silicon application was useful to increase
drought resistance of rice through the enhancement of photochemical efficiency and adjustment of the mineral nutrient absorption
in rice plants. 相似文献
19.
Kevin A. Hughes 《Polar Biology》2006,29(4):327-336
This study shows that increased UV-B arising from stratospheric ozone depletion over Antarctica reduced cell viability and
the maximum quantum yield of photochemistry (F
v/F
m) in a unicellular terrestrial microalga, Stichococcus bacillaris. In the UV waveband, rates of F
v/F
m decline increased with decreasing wavelength. Photosynthetically active radiation (PAR) also reduced F
v/F
m, though less than UV radiation. Further experiments under different ozone column thicknesses showed a significantly greater
decline in cell viability and F
v/F
m under ozone depletion compared with non-depleted conditions. The inhibitory effects of ambient solar radiation suggest that
S. bacillaris is unlikely to inhabit soil surfaces, but colonises shaded areas beneath soil surface particles. During periods of ozone
depletion, increases in the ratio of UV-B:PAR may reduce the thickness of the sub-surface zone where light conditions are
suitable for colonisation by this alga. 相似文献
20.
贺安娜;林文强;姚奕 《植物研究》2012,32(6):657-661
以盆栽1年的虎耳草为材料,研究遮荫条件下虎耳草叶片抗氧化酶体系活力、叶绿素含量、光合速率以及叶绿素荧光参数的变化,为虎耳草规模化栽培提供理论基础。结果表明:透光率50%条件下,叶绿素含量较高;虎耳草抗氧化酶活力最高;光饱和点(LSP)最大,最大光合速率(Amax)最高,光合速率日变化平均值最高,无“午休”;光系统Ⅱ的实际量子产量(ΦPSⅡ)、PSⅡ最大量子产量(Fv/Fm)和光化学猝灭系数(qP)最高,非光化学猝灭系数(qN)最低。这表明,虎耳草在怀化地区的最适光照条件是50%左右的透光率。 相似文献