As global temperature rise,the threat of heat stress to rapeseed production is becoming more obvious.Exploring the response characteristics of two important biological pathways,oil accumulation and photosynthesis,to h...As global temperature rise,the threat of heat stress to rapeseed production is becoming more obvious.Exploring the response characteristics of two important biological pathways,oil accumulation and photosynthesis,to heat stress during B.napus seed filling is helpful in the genetic improvement of heat-tolerant rapeseed.The effects of heat stress on seed oil accumulation and chlorophyll fluorescence characteristics of 29 B.napus germplasms with different oil content and environmental sensitivity,including 6 rapeseed varieties which exhibited environmentsensitive/insensitive and with high,medium or low oil content,were tested by whole plant heat stress or the in vitro silique culture system.Both assay exhibited similar trend on oil content of the rapeseed germplasms.The heat effect on the chlorophyll fluorescence kinetic parameters F_(v)/F_(m),ETR and Y(Ⅱ)were also consistent.Heat stress significantly decreased oil content,although there was abundant genetic variation on heat tolerance among the genotypes.Correlation analysis showed that the decrease rate of F_(v)/F_(m) of silique heat-stressed B.napus developing seed was positive correlative to the decrease rate of mature seed oil content of the whole plant heat-stressed rapeseed(R=0.9214,P-value<0.01).Overall,the results indicated that heat stress inhibited oil accumulation and photosynthesis in B.napus developing seed.The decrease rate of chlorophyll fluorescence parameter F_(v)/F_(m) of heat-stressed developing seed could be used as the index of heat tolerant rapeseed identification.Further,two heat insensitive rapeseed varieties with high oil content were identified.展开更多
[Objectives]To study the photosynthetic response mechanism of persimmon seedlings to salt stress.[Methods]The chlorophyll fluorescence parameters of Diospyros virginiana and Diospyros lotus seedlings under 4%salt stre...[Objectives]To study the photosynthetic response mechanism of persimmon seedlings to salt stress.[Methods]The chlorophyll fluorescence parameters of Diospyros virginiana and Diospyros lotus seedlings under 4%salt stress were studied by pot culture salt control method,including the minimal fluorescence(F_(0)),maximum fluorescence(F_(m)),potential activity of PS II(F_(v)/F_(0)),maximum photochemical efficiency of PS II(F_(v)/F_(m)),electron transport rate(ETR),actual photochemical efficiency of PS II(Y II),and photochemical quenching coefficient(q_(p)).[Results]Under 4%salt stress,the maximum fluorescence(F_(m)),maximum photochemical efficiency of PS II(F v/F m),and photochemical quenching coefficient(q_(p))of two persimmon plants decreased with time.The potential activity of PS II(F_(v)/F_(0)),actual photochemical efficiency of PS II(Y_(II)),and electron transport rate(ETR)decreased under salt stress.[Conclusions]This study indicates that the PS II reaction center in the persimmon leaves was damaged and the electron transport at the acceptor side was damaged under salt stress.It is expected to lay a foundation for the analysis of salt-tolerance mechanism of persimmon plants.展开更多
The Chinese Carbon Dioxide Observation Satellite Mission(TanSat)is the third satellite for global CO2 monitoring and is capable of detecting weak solar-induced chlorophyll fluorescence(SIF)signals with its advanced te...The Chinese Carbon Dioxide Observation Satellite Mission(TanSat)is the third satellite for global CO2 monitoring and is capable of detecting weak solar-induced chlorophyll fluorescence(SIF)signals with its advanced technical characteristics.Based on the Institute of Atmospheric Physics Carbon Dioxide Retrieval Algorithm for Satellite Remote Sensing(IAPCAS)platform,we successfully retrieved the TanSat global SIF product spanning the period of March 2017 to February 2018 with a physically based algorithm.This paper introduces the new TanSat SIF dataset and shows the global seasonal SIF maps.A brief comparison between the IAPCAS TanSat SIF product and the data-driven SVD(singular value decomposition)SIF product is also performed for follow-up algorithm optimization.The comparative results show that there are regional biases between the two SIF datasets and the linear correlations between them are above 0.73 for all seasons.The future SIF data product applications and requirements for SIF space observation are discussed.展开更多
Deficit irrigation is critical to global food production,particularly in arid and semi-arid regions with low precipitation.Given water shortage has threatened agricultural sustainability under the dry-land farming sys...Deficit irrigation is critical to global food production,particularly in arid and semi-arid regions with low precipitation.Given water shortage has threatened agricultural sustainability under the dry-land farming system in China,there is an urgent need to develop effective water-saving technologies.We carried out a field study under two cultivation techniques:(1) the ridge and furrow cultivation model(R);and(2) the conventional flat farming model(F),and three simulated precipitation levels(1,275 mm;2,200 mm;3,125 mm) with two deficit irrigation levels(150 and 75 mm).We demonstrated that under the ridge furrow(R) model,rainfall harvesting planting under 150 mm deficit irrigation combined with 200 mm simulated precipitation can considerably increase net photosynthesis rate(P_(n)),quantum yield of PSII(ΦPSⅡ),electron transport rate(ETR),performance index of photosynthetic PSII(F_(v)/F_(m)′),and transformation energy potential of PSII(F_(v)/F_(o)).In addition,during the jointing,anthesis and grain-filling stages,the grain and biomass yield in the R model are 18.9 and 11.1% higher than those in the flat cultivation model,respectively,primarily due to improved soil water contents.The winter wheat fluorescence parameters were significantly positively associated with the photosynthesis,biomass and wheat production.The result suggests that the R cultivation model with irrigation of 150 mm and simulated precipitation of 200 mm is an effective planting method for enhancing P_(n),biomass,wheat production,and chlorophyll fluorescence parameters in dry-land farming areas.展开更多
Red and blue light illumination has been reported to significantly affect plantlet growth.Potato is an important food and feed crop in the world and potato plantlet cultured in vitro plays an important role in potato ...Red and blue light illumination has been reported to significantly affect plantlet growth.Potato is an important food and feed crop in the world and potato plantlet cultured in vitro plays an important role in potato production.However,few studies have documented the effects of red and blue light on the growth of potato plantlets revealed at the transcriptome level.The objective of this study was to determine the growth and physiological responses of potato plantlets cultured in vitro under monochromatic red(RR),monochromatic blue(BB)as well as combined red and blue(RB)LEDs using the RNA-Seq technique.In total,3150 and 814 differentially expressed genes(DEGs)were detected in potato plantlets under RR and BB,respectively,compared to RB(used as control).Compared to the control,the DEGs enriched in"photosynthesis"and"photosynthesis-antenna proteins"metabolic pathways were up-regulated and down-regulated by BB and RR,respectively,which might be responsible for the increases and decreases of maximum quantum yield(F_(v)/F_(m)),photochemical quantum yield(φ_(PSII)),photochemical quenching(q_(P))and electron transfer rate(ETR)in BB and RR,respectively.Potato plantlets exhibited dwarfed stems and extended leaves under BB,whereas elongated stems and small leaves were induced under RR.These dramatically altered plantlet phenotypes were associated with variable levels of endogenous plant hormones gibberellin(GAs),indoleacetic acid(IAA)and cytokinins(CKs),as assessed in stems and leaves of potato plantlets.In addition,monochromatic red and blue LEDs trigged the opposite expression profiles of DEGs identified in the"plant hormone signal transduction"metabolic pathway,which were closely related to the endogenous plant hormone levels in potato plantlets.Our results provide insights into the responses of potato plantlets cultured in vitro to red and blue LEDs at the transcriptomic level and may contribute to improvements in the micro-propagation of potato plantlets cultured in vitro from the light spectrum aspect.展开更多
Vegetation phenology is an indicator of vegetation response to natural environmental changes and is of great significance for the study of global climate change and its impact on terrestrial ecosystems.The normalized ...Vegetation phenology is an indicator of vegetation response to natural environmental changes and is of great significance for the study of global climate change and its impact on terrestrial ecosystems.The normalized difference vegetation index(NDVI)and enhanced vegetation index(EVI),extracted from the Moderate Resolution Imaging Spectrometer(MODIS),are widely used to monitor phenology by calculating land surface reflectance.However,the applicability of the vegetation index based on‘greenness'to monitor photosynthetic activity is hindered by poor observation conditions(e.g.,ground shadows,snow,and clouds).Recently,satellite measurements of solar-induced chlorophyll fluorescence(SIF)from OCO-2 sensors have shown great potential for studying vegetation phenology.Here,we tested the feasibility of SIF in extracting phenological metrics in permafrost regions of the northeastern China,exploring the characteristics of SIF in the study of vegetation phenology and the differences between NDVI and EVI.The results show that NDVI has obvious SOS advance and EOS lag,and EVI is closer to SIF.The growing season length based on SIF is often the shortest,while it can represent the true phenology of vegetation because it is closely related to photosynthesis.SIF is more sensitive than the traditional remote sensing indices in monitoring seasonal changes in vegetation phenology and can compensate for the shortcomings of traditional vegetation indices.We also used the time series data of MODIS NDVI and EVI to extract phenological metrics in different permafrost regions.The results show that the length of growing season of vegetation in predominantly continuous permafrost(zone I)is longer than in permafrost with isolated taliks(zone II).Our results have certain significance for understanding the response of ecosystems in cold regions to global climate change.展开更多
Leaf early senescence caused by nutrition deficiency is one of the major limitation reasons in the world crop production. Potassium (K) is one of important nutrient elements in crop growth, which modifies dozens of en...Leaf early senescence caused by nutrition deficiency is one of the major limitation reasons in the world crop production. Potassium (K) is one of important nutrient elements in crop growth, which modifies dozens of enzyme activations and controls stomatal movement of photosynthesis. The yield and quality of maize (Zea Mays L.) have been limited due to K deficiency in plough layer soil. However, the mechanism of K deficiency tolerance is not fully understood in maize. In this study, two inbred lines, 099 (tolerance to potassium deficiency) and 835 (sensitive to potassium deficiency) were carried out to investigate the variations of chlorophyll content, photosynthetic and chlorophyll fluorescence parameters related with senescence under different K+ concentrations in maize at seedling stage. The results showed that the Chlorophyll a, b and (a + b) of 835 were significantly decreased under different K deficiency treatments, whereas those of 099 were remained normal. In addition, 099 showed a lower stomatal restriction and higher electronic transition capacity under different K deficiency treatments. The variations of F0, Fv/Fm, ΦPSⅡ, qP and NPQ in 835 were largely higher than those in 099. These results indicated that the inbred line 099 tolerance to K deficiency could keep chlorophyll content to maintain photosynthesis and to alleviate the injury of PSII under K deficiency condition. This study should contribute to explaining the physiological mechanism tolerance nutrition deficiency and improving breeding program in maize.展开更多
With Hemerocallis fulva‘Golden Doll'as an experimental material,the effects of different concentrations of neutral salt( NaCl) and alkaline salt( NaHCO3) stresses on photosynthesis and chlorophyll fluorescence ch...With Hemerocallis fulva‘Golden Doll'as an experimental material,the effects of different concentrations of neutral salt( NaCl) and alkaline salt( NaHCO3) stresses on photosynthesis and chlorophyll fluorescence characteristics in H. fulva seedlings were studied. The results showed that salt stress treatment significantly reduced the photosynthetic capacity of H. fulva. Under the NaCl and NaHCO3 stresses,the photosynthetic characteristics and chlorophyll fluorescence parameters of H. fulva seedlings were basically the same,but the photosynthetic characteristics and chlorophyll fluorescence parameter values of H. fulva seedlings were significantly different under different salt types and salt concentrations. With the extension of days of salt stress and the increase of salt concentration,the initial fluorescence yield( Fo) and non-photochemical quenching coefficient( NPQ) increased;the maximum fluorescence yield( Fm),maximum photochemical efficiency( Fv/Fm),PSII actual photosynthetic quantum yield( Y) and apparent quantum efficiency( AQY) all showed a downward trend;and moreover,with the extension of days of salt stress and the increase of salt concentration,the net photosynthetic rate( Pn) decreased and the intercellular CO2 concentration( Ci) increased. It was speculated that under salt stress,the photosynthetic characteristics of H. fulva leaves were inhibited. On the one hand,the non-stomatal limiting factor,i. e.,the chlorophyll content decreased,which led to the inhibition of photosynthetic characteristics. On the other hand,the decrease in the photosynthetic performance of mesophyll cells led to a decrease in the net photosynthetic rate of H. fulva. The changes of photosynthetic characteristics and chlorophyll fluorescence parameters in H. fulva caused by salt stress were closely related to the types of salts and salt concentration. High salt stress significantly inhibited the photosynthetic capacity of H. fulva‘Golden Doll',and the effect of NaHCO3 on H. fulva seedlings was significantly greater than that of NaCl.展开更多
Nitrogen(N)is a critical element for plant growth and productivity that influences photosynthesis and chlorophyll fluorescence.We investigated the effect of low-N stress on leaf photosynthesis and chlorophyll fluoresc...Nitrogen(N)is a critical element for plant growth and productivity that influences photosynthesis and chlorophyll fluorescence.We investigated the effect of low-N stress on leaf photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with difference in tolerance to low N levels.The low-N tolerant cultivar ZH311 and low-N sensitive cultivar XY508 were used as the test materials.A field experiment(with three N levels:N0,0 kg ha–1;N1,150 kg ha–1;N2,300 kg ha–1)in Jiyanyang,Sichuan Province,China,and a hydroponic experiment(with two N levels:CK,4 mmol L–1;LN,0.04 mmol L–1)in Chengdu,Sichuan Province,China were conducted.Low-N stress significantly decreased chlorophyll content and rapid light response curves of the maximum fluorescence under light(Fm′),fluorescence instable state(Fs),non-photochemical quenching(qN),the maximum efficiency of PSII photochemistry under dark-adaption(Fv/Fm),potential activity of PSII(Fv/Fo),and actual photochemical efficiency of PSII(ΦPSII)of leaves.Further,it increased the chlorophyll(Chl)a/Chl b values and so on.The light compensation point of ZH311 decreased,while that of XY508 increased.The degree of variation of these indices in low-N tolerant cultivars was lower than that in low-N sensitive cultivars,especially at the seedling stage.Maize could increase Chl a/Chl b,apparent quantum yield and light saturation point to adapt to N stress.Compared to low-N sensitive cultivars,low-N tolerant cultivars maintained a higher net photosynthetic rate and electron transport rate to maintain stronger PSII activity,which further promoted the ability to harvest and transfer light.This might be a photosynthetic mechanism by which low-N tolerant cultivar adapt to low-N stress.展开更多
When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produ...When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30? to 60?. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.展开更多
Waterlogging is one of the most factors limiting wheat production in the middle and lower reaches of the Yangtze River Plain of China,especially in the middle and late stages of wheat.Wheat varieties‘Jingmai102’(JM1...Waterlogging is one of the most factors limiting wheat production in the middle and lower reaches of the Yangtze River Plain of China,especially in the middle and late stages of wheat.Wheat varieties‘Jingmai102’(JM102)and‘Yangmai158’(YM158)were planted to study the dynamic changes of photosynthetic characteristics in flag leaf and the influence of waterlogging at anthesis on the yield and components and dry matter accumulation and remobilization of winter wheat in above ground.The results showed that the SPAD values slightly increased at 1 day after anthesis(d),and then kept decreasing with the increase of waterlogging time.The decrease in SPAD value was more remarkably in YM158 than that in JM102.As for the chlorophyll fluorescence parameters,the photochemical efficiency(Fv/Fm),potential activity(Fv/Fo)of photosystem II,and electronic transmission(Fm/Fo)on photosystem II increased first and then decreased with the increase of waterlogging days after anthesis.The quantum ratio of heat dissipation(Fo/Fm)had a tendency opposite to that of Fv/Fm,and the change range of JM102 was lower than that of YM158.For the grain yield and components,waterlogging at anthesis decreased the dry weight of single stem,grain yield,1 000-kernel weight,spikelet per panicle,and harvest index,and the reduction of JM102 was smaller than that of YM158.As for the accumulation and remobilization of dry matter,the accumulation of dry matter after anthesis decreased significantly under waterlogging condition(WL),and the reduction of JM102 was smaller than that of YM158.In conclusion,waterlogging at anthesis significantly affected the photosynthetic characteristics,yield and components in both varieties,but different varieties exhibited different tolerances to waterlogging stress and YM158 was more sensitive to water stress than JM102.展开更多
This research developed estimates of plant crown transpiration and water-use-efficiency using reflectance and derivative indices extracted from remotely sensed chlorophyll fluorescence measurements under natural condi...This research developed estimates of plant crown transpiration and water-use-efficiency using reflectance and derivative indices extracted from remotely sensed chlorophyll fluorescence measurements under natural conditions. Diurnal changes of leaf-level gas exchange (carbon assimilation rate (A), stomatal conductance (gs), transpiration rate (E)), chlorophyll fluorescence and canopy-scale remote sensing were measured on top crown of valley oak (Quercus lobata) in the foothills of central California, USA. The results indicated Q. lobata experienced saturating irradiance (PAR), which induced photoinhibition indicated by a decrease in the quantum efficiency of photosystem II (r2 = 0.648 with Fv ′/Fm′ and r2 = 0.73 with FPSII) and open reaction centers (qP;r2 = 0.699). The excess absorbed quantum energy was dissipated as heat through the Xanthophyll cycle and other processes (photorespiration and the water-water cycle) rather than energy emission as steady state chlorophyll fluorescence (Fs). An increase in leaf temperature caused by the activity of Xanthophyll cycle was correlated to a decrease in Fs (r2 = 0.381) and an increase in evaporative cooling through E (r2 = 0.800) and water use efficiency (WUE;r2 = 0.872).展开更多
Naked oat(Avena nuda L.)was originated from China,where soil nitrogen(N)is low availability.The responses of chlorophyll(Chl.)fluorescence parameters and leaf gas exchange to N application were analysed in this study....Naked oat(Avena nuda L.)was originated from China,where soil nitrogen(N)is low availability.The responses of chlorophyll(Chl.)fluorescence parameters and leaf gas exchange to N application were analysed in this study.After the N application rate ranged from 60 to 120 kg ha-1,variable fluorescence(F v),the maximal fluorescence(F m),the maximal photochemical efficiency(F v/F m),quantum yield(ΦPS II)of the photosynthetic system II(PS II),electron transport rate(ETR),and photochemical quenching coefficient(qP)increased with N application level,however,non-photochemical quenching coefficient(qN)decreased.Moreover,there was no difference in initial fluorescence(F o)with further more N enhancement.The maximum net photosynthetic rate(P max),apparent dark respiration rate(R d)and light saturation point(LSP)were improved with 40-56 kg N ha-1as basal fertilizer and 24-40 kg N ha-1as top dressing fertilizer applied at jointing stage.Initial quantum yield(α)was decreased with 24 kg N ha-1as basal fertilizer and 56 kg N ha-1as top dressing fertilizer.Flag-leaf net photosynthetic rate(P n)was significantly enhanced at the jointing and heading stages with 40-56 kg N ha-1as basal fertilizer;in addition,increased at grain filling stage of naked oat with 40-56 kg N ha-1as top dressing fertilizer.90 kg N ha-1(50-70%as basal fertilizer and 30-50%as top dressing fertilizer)application is recommended to alleviate photodamage of photosystem and improve the photosynthetic rate in naked oat.展开更多
The aim of this research was to study the influence of chlorsulfuron residue and cadmium on the enzymatic activity and photosynthetic apparatus of maize(Zea mays L.) plants. Chlorsulfuron and cadmium at 0.001 and 5.0 ...The aim of this research was to study the influence of chlorsulfuron residue and cadmium on the enzymatic activity and photosynthetic apparatus of maize(Zea mays L.) plants. Chlorsulfuron and cadmium at 0.001 and 5.0 mg kg–1, respectively, were mixed and applied to soil prior to planting. The levels of chlorsulfuron-and cadmium-induced stress to plants were estimated by growth, chlorophyll content, lipid peroxide content, enzyme activities, and major fluorescence parameters of chlorophyll(revealed by the fluorescence imaging system Fluor Cam). Chlorsulfuron negatively affected the chlorophyll content, photochemical efficiency of photosystem II in the dark-adapted state, the maximum efficiency of photosystem II, photochemical quenching coefficient, and steady-state fluorescence decline ratio in the leaves of maize seedlings. However, cadmium did not produce noticeable changes. Plants that were exposed to both chlorsulfuron and cadmium showed an obvious increase in the steady-state fluorescence decline ratio. These results implied that the seedlings possessed more resistance to cadmium than to chlorsulfuron and their resistance to chlorsulfuron toxicity was enhanced by the presence of cadmium. The results also suggested that chlorophyll fluorescence imaging reveals overall alterations within the leaves but may not reflect small-scale effects on tissues, as numeric values of specific parameters are averages of the data collected from the whole leaf.展开更多
Heavy metal contamination is one of the most important abiotic stresses affecting physiological activities of plants.We investigated the effects of cadmium(Cd) and lead(Pb) on chlorophyll fluorescence(Fv/Fm,Fo,and Fm)...Heavy metal contamination is one of the most important abiotic stresses affecting physiological activities of plants.We investigated the effects of cadmium(Cd) and lead(Pb) on chlorophyll fluorescence(Fv/Fm,Fo,and Fm),photosynthetic pigments(chlorophyll a and b),and proline in one-year-old seedlings of Robinia pseudoacacia.The seedlings were treated twice over a period of 10 days with Cd and Pb at concentrations of 0,250,500,1000 and2000 mg L-1.Saline solution containing Cd and Pb was sprayed on the leaves.Chlorophyll and proline contents were measured after 10 days.Chlorophyll fluorescence of R.pseudoacacia was affected slightly by high concentrations(1000,2000 mg L-1) of Cd and Pb.Chlorophyll a and a/b increased at 1000 and 2000 mg L-1of Cd and proline content of leaves was similar in all treatments of Cd and Pb.Our results indicated that photosynthetic sensitivity of R.pseudoacacia to Cd and Pb contamination was weak.Photosystem II chlorophyll pigments were not damaged by Pb and Cd stress.We conclude that chlorophyll fluorescence along with chlorophyll and proline contents are useful indicators of Cd and Pb stresses in R.pseudoacacia which widely planted in urban polluted regions in Iran.展开更多
Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of...Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol (Cinnamon soil), with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence (F0) of leaves was higher in the dry treatment (0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity) compared to the wet treatment (entire soil column at 75-80% of field capacity). The maximal fluorescence (Fm), the variable fluorescence (Fv), the photochemical efficiency (Fv/Fm) and potential activites (Fv/F0) of photosystem 2 (PS2) were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased Fv/Fm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 cm of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and Fv/Fm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants Fv/Fm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.展开更多
Photosynthesis and chlorophyll a fluorescence parameters, photochemical efficiency of PS II (Fv/Fm), photochemical quenching of PS II (qP), nonphotochemical quenching of PS II (NPQ), maximum activity of PS II (Fv/Fo) ...Photosynthesis and chlorophyll a fluorescence parameters, photochemical efficiency of PS II (Fv/Fm), photochemical quenching of PS II (qP), nonphotochemical quenching of PS II (NPQ), maximum activity of PS II (Fv/Fo) as well as electron transport rate (ETR), and quantum yield of PS II (ΦPS II) were measured on flag leaves of the winter wheat treated by methanol at different concentrations. The results revealed that photosynthesis was greatly improved by methanol, as indicated by higher photosynthetic rates and stomatal conductance. The enhancement effect of methanol on photosynthesis was maintained for 3-4 days. Different methanol concentration treatments also increased intercellular CO2 concentration and transpiration rates. No significant decline was found in Fv/Fm, Fv/Fo, and ΦPS II, which revealed no photoinhibition during methanol application in different methanol concentrations. Methanol showing no apparent inhibitory effects indicated higher potential photosynthetic capacity of flag leaves of winter wheat. However, the increase in photosynthesis was not followed by an increase in the photosynthetic activity (Fv/Fm), and fluorescence parameters did not indicate an improvement in intercellular CO2 concentration and PS II photochemical efficiency compared with the control, thereby encouraging us to propose that lower leaf temperatures caused by applied methanol would reduce both dark respiration and photorespiration (most importantly), thus, increasing net CO2 uptake and photosynthetic rates.展开更多
The photosynthetic characteristics of strawberry (Fragariaananassa Duch. cv. Toyonoka)leaves under illumination of identical light intensity(55-57% natural light) withdifferent light quality were studied. It was showe...The photosynthetic characteristics of strawberry (Fragariaananassa Duch. cv. Toyonoka)leaves under illumination of identical light intensity(55-57% natural light) withdifferent light quality were studied. It was showed that the chlorophyll content,maximal photochemical efficiency of PSⅡ(Fv/Fm), Fm/Fo, amount of inactive PSⅡreactioncenters (Fi-Fo) and rate of QA reduction were positively correlated with the red-light/blue-light ratios, but the chlorophyll (a/b) ratios were negatively correlated withthem. Carotenoid content of the leaves was maximum under the blue film, than under greenfilm, red film, white film and yellow film, and negatively correlated with the red/far-red ratios. The apparent quantum yield (AQY), photorespiratory rate (Pr) and carboxylationefficiency (CE) were also strongly affected by light quality. The photosynthetic rate(Pn) in strawberry leaves under green film was significantly lower than under all otherfilm. Our results suggested that light quality is an essential factor regulating thedevelopment of PSⅡ, and phytochrome and an independent blue light photoreceptor,possibly a cryptochrome, can regulate photosynthetic performance.展开更多
A cold-tolerant cultivar, Xiangnuo 1, and a cold-sensitive cultivar, IR50, were used to study the influence of chilling on photosynthetic rate and chlorophyll fluorescence parameters in rice seedlings. The photosynthe...A cold-tolerant cultivar, Xiangnuo 1, and a cold-sensitive cultivar, IR50, were used to study the influence of chilling on photosynthetic rate and chlorophyll fluorescence parameters in rice seedlings. The photosynthetic rates declined dramatically during chilling, and decreased by 48.7% and 67.5% in Xiangnuo 1 and IR50 seedlings, respectively, after being subjected to chilling treatment for two days. Chlorophyll fluorescence measurements showed that relatively higher qP and qNP in Xiangnuo 1 were maintained to dissipate the redundant excitation energy and protect the reaction centers from chill injury; accordingly, redundant excitation energy accumulated less in the reaction centers, and antenna systems were less injured by chilling in Xiangnuo 1. On the contrary, in IR50, qP and qNP declined rapidly while Ex increased, as the chilling persisted. This result indicated that the reaction centers and antenna systems in IR50 were damaged severely by chilling, which led to the lower photosynthetic rate.展开更多
基金funded by the Natural Science Foundation of Zhejiang Province(LY20C130006)the National Natural Science Foundation of China(32172018)the State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products(2010DS700124-ZZ1805).
文摘As global temperature rise,the threat of heat stress to rapeseed production is becoming more obvious.Exploring the response characteristics of two important biological pathways,oil accumulation and photosynthesis,to heat stress during B.napus seed filling is helpful in the genetic improvement of heat-tolerant rapeseed.The effects of heat stress on seed oil accumulation and chlorophyll fluorescence characteristics of 29 B.napus germplasms with different oil content and environmental sensitivity,including 6 rapeseed varieties which exhibited environmentsensitive/insensitive and with high,medium or low oil content,were tested by whole plant heat stress or the in vitro silique culture system.Both assay exhibited similar trend on oil content of the rapeseed germplasms.The heat effect on the chlorophyll fluorescence kinetic parameters F_(v)/F_(m),ETR and Y(Ⅱ)were also consistent.Heat stress significantly decreased oil content,although there was abundant genetic variation on heat tolerance among the genotypes.Correlation analysis showed that the decrease rate of F_(v)/F_(m) of silique heat-stressed B.napus developing seed was positive correlative to the decrease rate of mature seed oil content of the whole plant heat-stressed rapeseed(R=0.9214,P-value<0.01).Overall,the results indicated that heat stress inhibited oil accumulation and photosynthesis in B.napus developing seed.The decrease rate of chlorophyll fluorescence parameter F_(v)/F_(m) of heat-stressed developing seed could be used as the index of heat tolerant rapeseed identification.Further,two heat insensitive rapeseed varieties with high oil content were identified.
基金Supported by Science and Technology Research Project of Henan Provincial Science and Technology Department(222102110444)Introduction of Talent of Pingdingshan University(PXY-BSQD-202109).
文摘[Objectives]To study the photosynthetic response mechanism of persimmon seedlings to salt stress.[Methods]The chlorophyll fluorescence parameters of Diospyros virginiana and Diospyros lotus seedlings under 4%salt stress were studied by pot culture salt control method,including the minimal fluorescence(F_(0)),maximum fluorescence(F_(m)),potential activity of PS II(F_(v)/F_(0)),maximum photochemical efficiency of PS II(F_(v)/F_(m)),electron transport rate(ETR),actual photochemical efficiency of PS II(Y II),and photochemical quenching coefficient(q_(p)).[Results]Under 4%salt stress,the maximum fluorescence(F_(m)),maximum photochemical efficiency of PS II(F v/F m),and photochemical quenching coefficient(q_(p))of two persimmon plants decreased with time.The potential activity of PS II(F_(v)/F_(0)),actual photochemical efficiency of PS II(Y_(II)),and electron transport rate(ETR)decreased under salt stress.[Conclusions]This study indicates that the PS II reaction center in the persimmon leaves was damaged and the electron transport at the acceptor side was damaged under salt stress.It is expected to lay a foundation for the analysis of salt-tolerance mechanism of persimmon plants.
基金This study was supported by the National Key R&D Program of China(No.2016YFA0600203)the Key Research Program of the Chinese Academy of Sciences(ZDRW-ZS-2019-1&ZDRW-ZS-2019-2)the Youth Program of the National Natural Science Foundation of China(41905029).The TanSat L1B data service was provided by the International Reanalysis Cooperation on Carbon Satellite Data(IRCSD)(131211KYSB20180002)and the Cooperation on the Analysis of Carbon Satellite Data(CASA).The authors thank the OCO-2 team for providing the Level-2 SIF data products.
文摘The Chinese Carbon Dioxide Observation Satellite Mission(TanSat)is the third satellite for global CO2 monitoring and is capable of detecting weak solar-induced chlorophyll fluorescence(SIF)signals with its advanced technical characteristics.Based on the Institute of Atmospheric Physics Carbon Dioxide Retrieval Algorithm for Satellite Remote Sensing(IAPCAS)platform,we successfully retrieved the TanSat global SIF product spanning the period of March 2017 to February 2018 with a physically based algorithm.This paper introduces the new TanSat SIF dataset and shows the global seasonal SIF maps.A brief comparison between the IAPCAS TanSat SIF product and the data-driven SVD(singular value decomposition)SIF product is also performed for follow-up algorithm optimization.The comparative results show that there are regional biases between the two SIF datasets and the linear correlations between them are above 0.73 for all seasons.The future SIF data product applications and requirements for SIF space observation are discussed.
基金supported by the National Key Technologies R&D Program of China (2012BAD09B03)the China Postdoctoral Science Foundation Project Funding (2018M642614)+2 种基金the Special Fund for Agro-scientific Research, China (201303104)the Natural Science Foundation of Shandong Province, China (ZR2017ZB0422)the “Taishan Scholar” Project of Shandong Province, China。
文摘Deficit irrigation is critical to global food production,particularly in arid and semi-arid regions with low precipitation.Given water shortage has threatened agricultural sustainability under the dry-land farming system in China,there is an urgent need to develop effective water-saving technologies.We carried out a field study under two cultivation techniques:(1) the ridge and furrow cultivation model(R);and(2) the conventional flat farming model(F),and three simulated precipitation levels(1,275 mm;2,200 mm;3,125 mm) with two deficit irrigation levels(150 and 75 mm).We demonstrated that under the ridge furrow(R) model,rainfall harvesting planting under 150 mm deficit irrigation combined with 200 mm simulated precipitation can considerably increase net photosynthesis rate(P_(n)),quantum yield of PSII(ΦPSⅡ),electron transport rate(ETR),performance index of photosynthetic PSII(F_(v)/F_(m)′),and transformation energy potential of PSII(F_(v)/F_(o)).In addition,during the jointing,anthesis and grain-filling stages,the grain and biomass yield in the R model are 18.9 and 11.1% higher than those in the flat cultivation model,respectively,primarily due to improved soil water contents.The winter wheat fluorescence parameters were significantly positively associated with the photosynthesis,biomass and wheat production.The result suggests that the R cultivation model with irrigation of 150 mm and simulated precipitation of 200 mm is an effective planting method for enhancing P_(n),biomass,wheat production,and chlorophyll fluorescence parameters in dry-land farming areas.
基金funded by the Scientific Research Fund of College of Science&Technology,Ningbo University for the Introduction of High-level Talents,China(RC190006)。
文摘Red and blue light illumination has been reported to significantly affect plantlet growth.Potato is an important food and feed crop in the world and potato plantlet cultured in vitro plays an important role in potato production.However,few studies have documented the effects of red and blue light on the growth of potato plantlets revealed at the transcriptome level.The objective of this study was to determine the growth and physiological responses of potato plantlets cultured in vitro under monochromatic red(RR),monochromatic blue(BB)as well as combined red and blue(RB)LEDs using the RNA-Seq technique.In total,3150 and 814 differentially expressed genes(DEGs)were detected in potato plantlets under RR and BB,respectively,compared to RB(used as control).Compared to the control,the DEGs enriched in"photosynthesis"and"photosynthesis-antenna proteins"metabolic pathways were up-regulated and down-regulated by BB and RR,respectively,which might be responsible for the increases and decreases of maximum quantum yield(F_(v)/F_(m)),photochemical quantum yield(φ_(PSII)),photochemical quenching(q_(P))and electron transfer rate(ETR)in BB and RR,respectively.Potato plantlets exhibited dwarfed stems and extended leaves under BB,whereas elongated stems and small leaves were induced under RR.These dramatically altered plantlet phenotypes were associated with variable levels of endogenous plant hormones gibberellin(GAs),indoleacetic acid(IAA)and cytokinins(CKs),as assessed in stems and leaves of potato plantlets.In addition,monochromatic red and blue LEDs trigged the opposite expression profiles of DEGs identified in the"plant hormone signal transduction"metabolic pathway,which were closely related to the endogenous plant hormone levels in potato plantlets.Our results provide insights into the responses of potato plantlets cultured in vitro to red and blue LEDs at the transcriptomic level and may contribute to improvements in the micro-propagation of potato plantlets cultured in vitro from the light spectrum aspect.
基金Under the auspices of National Key Research and Development Projects(No.2018YFE0207800)National Natural Science Foundation of China(No.41871103)。
文摘Vegetation phenology is an indicator of vegetation response to natural environmental changes and is of great significance for the study of global climate change and its impact on terrestrial ecosystems.The normalized difference vegetation index(NDVI)and enhanced vegetation index(EVI),extracted from the Moderate Resolution Imaging Spectrometer(MODIS),are widely used to monitor phenology by calculating land surface reflectance.However,the applicability of the vegetation index based on‘greenness'to monitor photosynthetic activity is hindered by poor observation conditions(e.g.,ground shadows,snow,and clouds).Recently,satellite measurements of solar-induced chlorophyll fluorescence(SIF)from OCO-2 sensors have shown great potential for studying vegetation phenology.Here,we tested the feasibility of SIF in extracting phenological metrics in permafrost regions of the northeastern China,exploring the characteristics of SIF in the study of vegetation phenology and the differences between NDVI and EVI.The results show that NDVI has obvious SOS advance and EOS lag,and EVI is closer to SIF.The growing season length based on SIF is often the shortest,while it can represent the true phenology of vegetation because it is closely related to photosynthesis.SIF is more sensitive than the traditional remote sensing indices in monitoring seasonal changes in vegetation phenology and can compensate for the shortcomings of traditional vegetation indices.We also used the time series data of MODIS NDVI and EVI to extract phenological metrics in different permafrost regions.The results show that the length of growing season of vegetation in predominantly continuous permafrost(zone I)is longer than in permafrost with isolated taliks(zone II).Our results have certain significance for understanding the response of ecosystems in cold regions to global climate change.
文摘Leaf early senescence caused by nutrition deficiency is one of the major limitation reasons in the world crop production. Potassium (K) is one of important nutrient elements in crop growth, which modifies dozens of enzyme activations and controls stomatal movement of photosynthesis. The yield and quality of maize (Zea Mays L.) have been limited due to K deficiency in plough layer soil. However, the mechanism of K deficiency tolerance is not fully understood in maize. In this study, two inbred lines, 099 (tolerance to potassium deficiency) and 835 (sensitive to potassium deficiency) were carried out to investigate the variations of chlorophyll content, photosynthetic and chlorophyll fluorescence parameters related with senescence under different K+ concentrations in maize at seedling stage. The results showed that the Chlorophyll a, b and (a + b) of 835 were significantly decreased under different K deficiency treatments, whereas those of 099 were remained normal. In addition, 099 showed a lower stomatal restriction and higher electronic transition capacity under different K deficiency treatments. The variations of F0, Fv/Fm, ΦPSⅡ, qP and NPQ in 835 were largely higher than those in 099. These results indicated that the inbred line 099 tolerance to K deficiency could keep chlorophyll content to maintain photosynthesis and to alleviate the injury of PSII under K deficiency condition. This study should contribute to explaining the physiological mechanism tolerance nutrition deficiency and improving breeding program in maize.
基金Supported by Science and Technology Research Project of Institutions of Higher Education in Hebei Province (BJ2017102)Tangshan Normal University Doctoral Fund (2014A06)。
文摘With Hemerocallis fulva‘Golden Doll'as an experimental material,the effects of different concentrations of neutral salt( NaCl) and alkaline salt( NaHCO3) stresses on photosynthesis and chlorophyll fluorescence characteristics in H. fulva seedlings were studied. The results showed that salt stress treatment significantly reduced the photosynthetic capacity of H. fulva. Under the NaCl and NaHCO3 stresses,the photosynthetic characteristics and chlorophyll fluorescence parameters of H. fulva seedlings were basically the same,but the photosynthetic characteristics and chlorophyll fluorescence parameter values of H. fulva seedlings were significantly different under different salt types and salt concentrations. With the extension of days of salt stress and the increase of salt concentration,the initial fluorescence yield( Fo) and non-photochemical quenching coefficient( NPQ) increased;the maximum fluorescence yield( Fm),maximum photochemical efficiency( Fv/Fm),PSII actual photosynthetic quantum yield( Y) and apparent quantum efficiency( AQY) all showed a downward trend;and moreover,with the extension of days of salt stress and the increase of salt concentration,the net photosynthetic rate( Pn) decreased and the intercellular CO2 concentration( Ci) increased. It was speculated that under salt stress,the photosynthetic characteristics of H. fulva leaves were inhibited. On the one hand,the non-stomatal limiting factor,i. e.,the chlorophyll content decreased,which led to the inhibition of photosynthetic characteristics. On the other hand,the decrease in the photosynthetic performance of mesophyll cells led to a decrease in the net photosynthetic rate of H. fulva. The changes of photosynthetic characteristics and chlorophyll fluorescence parameters in H. fulva caused by salt stress were closely related to the types of salts and salt concentration. High salt stress significantly inhibited the photosynthetic capacity of H. fulva‘Golden Doll',and the effect of NaHCO3 on H. fulva seedlings was significantly greater than that of NaCl.
基金financially supported by the Sichuan Key Technology Support Program of China (2014NZ0040)the Special Fund for Agro-scientific Research in the Public Interest of China (20150312705)
文摘Nitrogen(N)is a critical element for plant growth and productivity that influences photosynthesis and chlorophyll fluorescence.We investigated the effect of low-N stress on leaf photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with difference in tolerance to low N levels.The low-N tolerant cultivar ZH311 and low-N sensitive cultivar XY508 were used as the test materials.A field experiment(with three N levels:N0,0 kg ha–1;N1,150 kg ha–1;N2,300 kg ha–1)in Jiyanyang,Sichuan Province,China,and a hydroponic experiment(with two N levels:CK,4 mmol L–1;LN,0.04 mmol L–1)in Chengdu,Sichuan Province,China were conducted.Low-N stress significantly decreased chlorophyll content and rapid light response curves of the maximum fluorescence under light(Fm′),fluorescence instable state(Fs),non-photochemical quenching(qN),the maximum efficiency of PSII photochemistry under dark-adaption(Fv/Fm),potential activity of PSII(Fv/Fo),and actual photochemical efficiency of PSII(ΦPSII)of leaves.Further,it increased the chlorophyll(Chl)a/Chl b values and so on.The light compensation point of ZH311 decreased,while that of XY508 increased.The degree of variation of these indices in low-N tolerant cultivars was lower than that in low-N sensitive cultivars,especially at the seedling stage.Maize could increase Chl a/Chl b,apparent quantum yield and light saturation point to adapt to N stress.Compared to low-N sensitive cultivars,low-N tolerant cultivars maintained a higher net photosynthetic rate and electron transport rate to maintain stronger PSII activity,which further promoted the ability to harvest and transfer light.This might be a photosynthetic mechanism by which low-N tolerant cultivar adapt to low-N stress.
基金supported by the National Natural Science Foundation of China (Nos.41406199,41506197)the Program Foundation of Nanjing University of Information Science and Technology (No.KHYS1301)+1 种基金the Doctoral Scientific Research Foundation of Liaoning Province (No.201501190)the Fundamental Research Funds for the Central Universities (No.3132015081)
文摘When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30? to 60?. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.
基金Supported by the National Key Research and Development Program of China(2016YFD0300107,2017YFD0300202-3)National Natural Science Foundation of China(31371580,31871578)
文摘Waterlogging is one of the most factors limiting wheat production in the middle and lower reaches of the Yangtze River Plain of China,especially in the middle and late stages of wheat.Wheat varieties‘Jingmai102’(JM102)and‘Yangmai158’(YM158)were planted to study the dynamic changes of photosynthetic characteristics in flag leaf and the influence of waterlogging at anthesis on the yield and components and dry matter accumulation and remobilization of winter wheat in above ground.The results showed that the SPAD values slightly increased at 1 day after anthesis(d),and then kept decreasing with the increase of waterlogging time.The decrease in SPAD value was more remarkably in YM158 than that in JM102.As for the chlorophyll fluorescence parameters,the photochemical efficiency(Fv/Fm),potential activity(Fv/Fo)of photosystem II,and electronic transmission(Fm/Fo)on photosystem II increased first and then decreased with the increase of waterlogging days after anthesis.The quantum ratio of heat dissipation(Fo/Fm)had a tendency opposite to that of Fv/Fm,and the change range of JM102 was lower than that of YM158.For the grain yield and components,waterlogging at anthesis decreased the dry weight of single stem,grain yield,1 000-kernel weight,spikelet per panicle,and harvest index,and the reduction of JM102 was smaller than that of YM158.As for the accumulation and remobilization of dry matter,the accumulation of dry matter after anthesis decreased significantly under waterlogging condition(WL),and the reduction of JM102 was smaller than that of YM158.In conclusion,waterlogging at anthesis significantly affected the photosynthetic characteristics,yield and components in both varieties,but different varieties exhibited different tolerances to waterlogging stress and YM158 was more sensitive to water stress than JM102.
文摘This research developed estimates of plant crown transpiration and water-use-efficiency using reflectance and derivative indices extracted from remotely sensed chlorophyll fluorescence measurements under natural conditions. Diurnal changes of leaf-level gas exchange (carbon assimilation rate (A), stomatal conductance (gs), transpiration rate (E)), chlorophyll fluorescence and canopy-scale remote sensing were measured on top crown of valley oak (Quercus lobata) in the foothills of central California, USA. The results indicated Q. lobata experienced saturating irradiance (PAR), which induced photoinhibition indicated by a decrease in the quantum efficiency of photosystem II (r2 = 0.648 with Fv ′/Fm′ and r2 = 0.73 with FPSII) and open reaction centers (qP;r2 = 0.699). The excess absorbed quantum energy was dissipated as heat through the Xanthophyll cycle and other processes (photorespiration and the water-water cycle) rather than energy emission as steady state chlorophyll fluorescence (Fs). An increase in leaf temperature caused by the activity of Xanthophyll cycle was correlated to a decrease in Fs (r2 = 0.381) and an increase in evaporative cooling through E (r2 = 0.800) and water use efficiency (WUE;r2 = 0.872).
基金the study grants from the Special Fund for Agro-Scientific Research in the Public Interest,China(nyhyzx07-009-2)the Earmarked Fund for China Agriculture Research System(CARS-08-B-1)
文摘Naked oat(Avena nuda L.)was originated from China,where soil nitrogen(N)is low availability.The responses of chlorophyll(Chl.)fluorescence parameters and leaf gas exchange to N application were analysed in this study.After the N application rate ranged from 60 to 120 kg ha-1,variable fluorescence(F v),the maximal fluorescence(F m),the maximal photochemical efficiency(F v/F m),quantum yield(ΦPS II)of the photosynthetic system II(PS II),electron transport rate(ETR),and photochemical quenching coefficient(qP)increased with N application level,however,non-photochemical quenching coefficient(qN)decreased.Moreover,there was no difference in initial fluorescence(F o)with further more N enhancement.The maximum net photosynthetic rate(P max),apparent dark respiration rate(R d)and light saturation point(LSP)were improved with 40-56 kg N ha-1as basal fertilizer and 24-40 kg N ha-1as top dressing fertilizer applied at jointing stage.Initial quantum yield(α)was decreased with 24 kg N ha-1as basal fertilizer and 56 kg N ha-1as top dressing fertilizer.Flag-leaf net photosynthetic rate(P n)was significantly enhanced at the jointing and heading stages with 40-56 kg N ha-1as basal fertilizer;in addition,increased at grain filling stage of naked oat with 40-56 kg N ha-1as top dressing fertilizer.90 kg N ha-1(50-70%as basal fertilizer and 30-50%as top dressing fertilizer)application is recommended to alleviate photodamage of photosystem and improve the photosynthetic rate in naked oat.
基金supported by grants from the National Natural Science Foundation of China(30740037)the Special Fund for Agro-scientific Research in the Public Interest,China(201103024)the Foundation for Graduate Innovation,Shanxi University,China(011452901009)
文摘The aim of this research was to study the influence of chlorsulfuron residue and cadmium on the enzymatic activity and photosynthetic apparatus of maize(Zea mays L.) plants. Chlorsulfuron and cadmium at 0.001 and 5.0 mg kg–1, respectively, were mixed and applied to soil prior to planting. The levels of chlorsulfuron-and cadmium-induced stress to plants were estimated by growth, chlorophyll content, lipid peroxide content, enzyme activities, and major fluorescence parameters of chlorophyll(revealed by the fluorescence imaging system Fluor Cam). Chlorsulfuron negatively affected the chlorophyll content, photochemical efficiency of photosystem II in the dark-adapted state, the maximum efficiency of photosystem II, photochemical quenching coefficient, and steady-state fluorescence decline ratio in the leaves of maize seedlings. However, cadmium did not produce noticeable changes. Plants that were exposed to both chlorsulfuron and cadmium showed an obvious increase in the steady-state fluorescence decline ratio. These results implied that the seedlings possessed more resistance to cadmium than to chlorsulfuron and their resistance to chlorsulfuron toxicity was enhanced by the presence of cadmium. The results also suggested that chlorophyll fluorescence imaging reveals overall alterations within the leaves but may not reflect small-scale effects on tissues, as numeric values of specific parameters are averages of the data collected from the whole leaf.
基金supported by Iran Research Institute of Forests and Rangelandsthe Laboratory of Horticultural Sciences of the University of Tehran
文摘Heavy metal contamination is one of the most important abiotic stresses affecting physiological activities of plants.We investigated the effects of cadmium(Cd) and lead(Pb) on chlorophyll fluorescence(Fv/Fm,Fo,and Fm),photosynthetic pigments(chlorophyll a and b),and proline in one-year-old seedlings of Robinia pseudoacacia.The seedlings were treated twice over a period of 10 days with Cd and Pb at concentrations of 0,250,500,1000 and2000 mg L-1.Saline solution containing Cd and Pb was sprayed on the leaves.Chlorophyll and proline contents were measured after 10 days.Chlorophyll fluorescence of R.pseudoacacia was affected slightly by high concentrations(1000,2000 mg L-1) of Cd and Pb.Chlorophyll a and a/b increased at 1000 and 2000 mg L-1of Cd and proline content of leaves was similar in all treatments of Cd and Pb.Our results indicated that photosynthetic sensitivity of R.pseudoacacia to Cd and Pb contamination was weak.Photosystem II chlorophyll pigments were not damaged by Pb and Cd stress.We conclude that chlorophyll fluorescence along with chlorophyll and proline contents are useful indicators of Cd and Pb stresses in R.pseudoacacia which widely planted in urban polluted regions in Iran.
基金supported by the National Natural Science Foundation of China (NSFC 50809068)the foundation of the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,China (10502)+1 种基金the China Postdoctoral Science Foundation (20080441196)the West Light Foundation of the Chinese Academy of Science
文摘Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol (Cinnamon soil), with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence (F0) of leaves was higher in the dry treatment (0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity) compared to the wet treatment (entire soil column at 75-80% of field capacity). The maximal fluorescence (Fm), the variable fluorescence (Fv), the photochemical efficiency (Fv/Fm) and potential activites (Fv/F0) of photosystem 2 (PS2) were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased Fv/Fm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 cm of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and Fv/Fm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants Fv/Fm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.
文摘Photosynthesis and chlorophyll a fluorescence parameters, photochemical efficiency of PS II (Fv/Fm), photochemical quenching of PS II (qP), nonphotochemical quenching of PS II (NPQ), maximum activity of PS II (Fv/Fo) as well as electron transport rate (ETR), and quantum yield of PS II (ΦPS II) were measured on flag leaves of the winter wheat treated by methanol at different concentrations. The results revealed that photosynthesis was greatly improved by methanol, as indicated by higher photosynthetic rates and stomatal conductance. The enhancement effect of methanol on photosynthesis was maintained for 3-4 days. Different methanol concentration treatments also increased intercellular CO2 concentration and transpiration rates. No significant decline was found in Fv/Fm, Fv/Fo, and ΦPS II, which revealed no photoinhibition during methanol application in different methanol concentrations. Methanol showing no apparent inhibitory effects indicated higher potential photosynthetic capacity of flag leaves of winter wheat. However, the increase in photosynthesis was not followed by an increase in the photosynthetic activity (Fv/Fm), and fluorescence parameters did not indicate an improvement in intercellular CO2 concentration and PS II photochemical efficiency compared with the control, thereby encouraging us to propose that lower leaf temperatures caused by applied methanol would reduce both dark respiration and photorespiration (most importantly), thus, increasing net CO2 uptake and photosynthetic rates.
基金supported by the National Natura1 Science Foundation of China(39730340)
文摘The photosynthetic characteristics of strawberry (Fragariaananassa Duch. cv. Toyonoka)leaves under illumination of identical light intensity(55-57% natural light) withdifferent light quality were studied. It was showed that the chlorophyll content,maximal photochemical efficiency of PSⅡ(Fv/Fm), Fm/Fo, amount of inactive PSⅡreactioncenters (Fi-Fo) and rate of QA reduction were positively correlated with the red-light/blue-light ratios, but the chlorophyll (a/b) ratios were negatively correlated withthem. Carotenoid content of the leaves was maximum under the blue film, than under greenfilm, red film, white film and yellow film, and negatively correlated with the red/far-red ratios. The apparent quantum yield (AQY), photorespiratory rate (Pr) and carboxylationefficiency (CE) were also strongly affected by light quality. The photosynthetic rate(Pn) in strawberry leaves under green film was significantly lower than under all otherfilm. Our results suggested that light quality is an essential factor regulating thedevelopment of PSⅡ, and phytochrome and an independent blue light photoreceptor,possibly a cryptochrome, can regulate photosynthetic performance.
文摘A cold-tolerant cultivar, Xiangnuo 1, and a cold-sensitive cultivar, IR50, were used to study the influence of chilling on photosynthetic rate and chlorophyll fluorescence parameters in rice seedlings. The photosynthetic rates declined dramatically during chilling, and decreased by 48.7% and 67.5% in Xiangnuo 1 and IR50 seedlings, respectively, after being subjected to chilling treatment for two days. Chlorophyll fluorescence measurements showed that relatively higher qP and qNP in Xiangnuo 1 were maintained to dissipate the redundant excitation energy and protect the reaction centers from chill injury; accordingly, redundant excitation energy accumulated less in the reaction centers, and antenna systems were less injured by chilling in Xiangnuo 1. On the contrary, in IR50, qP and qNP declined rapidly while Ex increased, as the chilling persisted. This result indicated that the reaction centers and antenna systems in IR50 were damaged severely by chilling, which led to the lower photosynthetic rate.
