Effects of Salicylic Acid on Photosynthesis and Chlorophyll Fluorescence Characteristics of Fluecured Tobacco Leaf in Subdued Light

[Objective] This study aimed to test whether salicylic acid （SA） can im-prove the physiological functions of flue-cured tobacco under subdued light condition, and to determine the mechanism of its action. [Method] The tobacco plants under subdued light were foliar-sprayed with 100 mg/L of SA. Then, the physiological in-dices such as plant fresh weight and dry weight, chlorophyl content, photosynthetic parameters and chlorophyl fluorescence parameters were measured. SPSS17.0 and Excellwere adopted for variance analysis and significance test. [Result] The leaf photosynthetic rate （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） of tobacco plants in subdued light were al decreased while the intercellular CO2 con-centration （Ci） was increased, suggesting that non-stomatal limitation led to the de-crease of Pn under weak light intensity stress. SA released the inhibition of tobacco plant growth in weak light, as it elevated the leaf photosynthetic rate, the maximum photochemical efficiency of PSⅡ, potential activity of PSⅡ, effective photochemical efficiency of PSⅡ and photochemical quenching coefficient in weak light significant-ly, and reduced the non-photochemical quenching coefficient. [Conclusion] SA has significant effects on the photosynthetic characteristics of flue-cured tobacco in weak light, and it can improve the synthesis or distribution of photosynthesis product, and the efficiency of light energy, conducive to plant growth and development.

Effect of low-nitrogen stress on photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with different low-nitrogen tolerances

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.

Effect of Light Quality on Photosynthesis and Chlorophyll Fluorescence in Strawberry Leaves

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.

Improvement in winter wheat productivity through regulating PSⅡ photochemistry,photosynthesis and chlorophyll fluorescence under deficit irrigation conditions

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.

Effect of Different Norms of Under-Mulch-Drip Irrigation on Diurnal Changes of Photosynthesis and Chlorophyll Fluorescence Parameter in High Yield Cotton of Xinjiang

Under-mulch-drip irrigation is an advanced irrigation technique, which combines plastic-film-covered cultivation with drip irrigation. The influence of different norms of under-mulch-drip irrigation on diurnal changes of photosynthetic rates and chlorophyll fluorescence parameters of cotton was studied, in order to understand the physiological mechanisms of water-saving and high-yielding farming in Xinjiang. Results indicated that limited drip irrigation, which supplies 2/3 of 375 m3 ha-1, the widely-used irrigation norm in cotton cultivation in Xinjiang, caused a water deficit in cotton field. Compared with the proper drip irrigation, the leaf photosynthetic rate under limited drip irrigation decreased during 9:00 to 11:00 a. m. , and was significantly suppressed at midday, and then recovered afterwards. Using the chlorophyll fluorescence method, the absorption, transfer and transformation features of solar radiation by cotton leaf were investigated. Under limited drip irrigation, the variable fluorescence (Fv) and primary light transfer efficiency of PSII (Fv/Fm) in cotton leaves were reduced because of the high light intensities and high temperatures at noon, and the decrease in XinluzaoS was greater than that in Xinluzao6. Therefore, it could be concluded that Xinluzao6 has a higher drought-tolerance, and the Fv/Fm ratio could be used as a drought-resistance index for cotton.

Effect of Methanol on Photosynthesis and Chlorophyll Fluorescence of Flag Leaves of Winter Wheat

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 （ФPS 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 ФPS 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.

Effects of Different Potassium Stress on Leaf Photosynthesis and Chlorophyll Fluorescence in Maize (Zea Mays L.) at Seedling Stage

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.

Effects of NaCl and NaHCO3 Stress on Photosynthesis and Chlorophyll Fluorescence Characteristics of Hemerocallis fulva ‘Golden Doll’

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.

Effects of Thallium Stress on Photosynthesis, Chlorophyll Fluorescence Parameters and Antioxidant Enzymes Activities of Coix Lacryma-jobi

Levels of T1 （Thallium） in soil from 0 （control） to 50 μg/L through 0.2, 0.5, 1 and 2.5μg/L were directly and positively correlated to levels of T1 in plant tissue, the accumulation being maximum in roots, intermediate in leaves and minimum in stems. Thallium, especially at higher concentrations, adversely affected photosynthesis （as judged based on chlorophyll fluorescence parameters）, suggesting inhibition of photo-activation of PSII （Photosystems II）, and also decreased the rate of photosynthesis, the rate of transpiration and stomatal conductivity drastically. Exposure to TI also increased the activity of CAT （Catalase） （except at 1 μg/L） and POD （Peroxidase） （except at 0.2 μg/L）, suggesting that the antioxidant systems in Coix lacryma-jobi were the main contributors of CAT and SOD （Superoxide Dismutase） and that the tolerance of C. lacryma-jobi to T1 is mainly due to this induced antioxidant machinery.

Fluorescence of Chlorophyll a for Discovering Inhibitors of Photosynthesis in Plant Extracts

Aims: Twelve crude extracts were prepared from different parts of Pluchea sagittalis, Cecropia palmata and Brachiaria brizantha, and their effect on the light reaction of photosynthesis. Study Design: Use of fluorescence of ChL a (Chlorophyll a) to detect inhibitors of photosynthesis in plant extracts. Place and Duration of Study: Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Departamento de Ciências Exatas e da Terra, Universidade Federal de Sao Paulo (UNIFESP), between July 2015 and January 2016. Methodology: The samples had their effect on the light reaction of photosynthesis studied by Chlorophyll a (Chl a) fluorescence transient by the use of chloroplasts isolated from spinach leaves. As negative controls we used the same amounts of DMSO that have been employed to solubilize the samples, and as positive control we have used 10 μM of the commercial herbicide DCMU (Diuron). Results: The extracts inhibited the photosynthesis, and their inhibition sites were located in the range of electron flow from OEC complex and between P680 to QA of PS II, and inhibited the photosystem II (PS II) by inducing the appearance of the transient bands K and J. Conclusion: Our results suggest an indicative that the photochemical apparatus probably is failing at the donor and acceptor sides of PSII, causing damage to electron transport during the photosynthesis phenomenon.

Effect of Low Light on the Characteristics of Photosynthesis and Chlorophyll a Fluorescence During Leaf Development of Sweet Pepper

Low light stress is one of the main limiting factors which influence the production of sweet pepper under protected cultivation in China. In this experiment, two genotypes of sweet pepper, ShY （low light-tolerant genotype） and 20078 （low light-sensitive genotype）, were used to study the effects of low light （photosynthetic photon flux density, PPFD was 75- 100 umol m-2 s-1, control 450-500 umol m-2 s-1） on photosynthesis during leaf development. The result indicated that under low light chlorophyll content, net photosynthetic rate （PN）, photosynthetic apparent quantum efficiency （Фi） and carboxylation efficiency （CE） of sweet pepper leaves increased gradually and decreased after reaching the maximum levels. The time to reach the peak values for all the above parameters was delayed, whereas the light compensation point （LCP） decreased gradually along with leaf expansion. The decrease in maximum quantum yield of PS II （Fv/Fm） was not observed at any stages of the leaf development under low light condition, but the actual PS II efficiency under irradiance （ФPS II） was lower accompanied by an increased non-photochemical quenching （NPQ） in young and/or old leaves compared with mature leaves. The antenna thermal dissipation （D） was a main way of heat dissipation when young leaves received excessive light energy, while the decline in photosynthetic function in senescence leaf was mostly owing to the decrease in carbon assimilation capacity, followed by a significantly increased allocation of excessive energy （Ex）. Compared with 20078, ShY could maintain higher PN, ФPS II and lower QA reduction state for a longer time during leaf development. Thus, in ShY photosynthetic efficiency and the activity of electron transport of PS II were not significantly affected due to low light stress.

Studies on the Characteristics of Chlorophyll Fluorescence of Winter Wheat Flag Leaves at Different Developing Stages

The parameters of fluorescence induction kinetics and the maximal light-saturated net CO2 assimilation rate (P-sat) of the flag leaves of four cultivars of winter wheat (Triticum aestivum L.) were compared at three different developing stages for the first time. From the blooming stage to the milky stage, the quantum efficiency of PS II photochemistry (F-v/F-m) declined slightly only at the milk stage. The photochemical quenching co-efficient (qP), actual quantum yield of photosystem II (PS II)electron transport (Phi (PSII)) and P-sat decreased substantially (> 15%), while the non-photochemical quenching co-efficient (qN) increased significantly (> 100%). There existed a linear correlation between the Phi (PSII) and the P-sat (r = 0.918). The results indicate that with the senescence of the flag leaves of winter wheat the photosynthetic efficiency including that of the energy transport and the CO2 assimilation significantly decreased.

Characteristics of CO_2 Exchange and Chlorophyll Fluorescence of Transgenic Rice with C_4 Genes

The responses of photosynthesis of phosphoenopyruvate carboxylase (PEPC), pyrurate dikinase (PPDK), NADP-malic enzyme (NADP-ME) and PPDK+PEPC transgenic rice (Oryza saltiva L.) plant to light, temperature, CO 2 and the characteristics of chlorophyll fluorescence under photoinhibition conditions were studied. The results were as follows: 1. The light-saturated photosynthetic rates of transgenic rice plants were higher than that of wild type, in which the light-saturated point of PEPC and PPDK+PEPC transgenic rice plants was 200 μmol·m -2·s -1 higher than that of untransformed rice and the light-saturated photosynthetic rates were 51.6% and 58.5% respectively. The carboxylation efficiency of PEPC transgenic rice plant increased by 49.3% and the CO 2 compensation point decreased by 26.2% than that of untransformed rice. Under high temperature (35 ℃), the photosynthetic rate of PEPC transgenic rice plant was higher over 17.5% than that of untransformed rice. 2. On the 8th day after photoinhibition treatment, the PSⅡ photochemical efficiency (F v/F m) and photochemical quenching (qP) of PEPC and PPDK+PEPC transgenic rice plants decreased by about 20%-30% while the non-photochemical quenching (qN) increased by approximately 30%. But F v/F m and qP of untransformed rice decreased by over 50% while qN increased by less than 10%. The result suggested that transgenic rice plants were more tolerant to photoinhibition.

Effects of Water Stress on Photosynthesis and Fluorescence Characteristics in Peony

[ Objective] Study on the photosynthesis and fluorescence characteristics in peony under water stress. [ Method ] The two peony varieties Huhong and Luoyanghong were treated by different water stress for determining the photosynthesis and fluorescence characteristics. [ Result ] With the aggravation of water stress, the net photosynthetic rate （Pn） and stomatal conductance （Gs） decreased, while the intercellular CO2 concentration （Ci） increased. Drought could decrease Pn, constrain gas exchange and change the daily photosynthesis. Fo of peony leaf increased and Fv/Fm decreased under water stress especially water logging, causing the inactivation of the PS II reaction center, and the chlorophyll fluorescence characters gradually recovered until afternoon. [ Conclusion] The 75% soil relative water content （SRWC） is the best condition for growth of peony. Compared with drought, water logging is more unfit for the growth of peony. For the two varieties, Huhong assumed more tolerance to drought, accordingly more adaptability.

Characteristics of Chlorophyll Fluorescence and Membrane-lipid Peroxidation of Various High-yield Rices Under Photooxidation Conditions

Using various high-yield rices (Oryza sativa L.) such as japonica cultivar 9516, two parental line hybrid rice between subspecies with more japonica element Peiai 64/E32, Liangyoupeijiu (Peiai 64/9311), and indica hybrid rices X07S/Zihui 100, Gangyou 881, Shanyou 63 as the materials, the characteristics of chlorophyll fluorescence and membrane-lipid peroxidation of detached leaves at booting stage under photooxidation conditions were studied. In comparison with indica hybrid rice, after the photooxidation treatment, the primary photochemical efficiency of PS II (F-v/F-m), quantum yield of linear electron transport of PS II (Phi(PSII)) and photochemical quenching coefficient (qP) in japonica cultivar and hybrid rice with japonica decreased less. This indicated that high-yield rice with japonica was able to maintain higher capability of light energy conversion, resulting in the alleviation of photoinhibition. Meanwhile, the higher activities of protective enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) led to the less accumulation of endogenous active oxygen (O-(2)(radical anion), H2O2) and less content of the malondialdehyde (MDA) and the less decline of chlorophyll and protein contents, indicating a stronger tolerance to photooxidation. The changes in contents of chlorophyll and protein among various nee cultivars during photooxidation treatment were consistent with the decline of chlorophyll content from heading stage to maturation stage under natural conditions. Statistical analysis showed that there was a significant correlation between the indexes of tolerance to photooxidation and the rate of seed setting, implying that the cultivar tolerated to photooxidation had higher resistance to early aging of leaf. These results suggested that from a view of superhigh-yield breeding, considering both the utilization of heterosis and the resistance to early aging of leaf, introduction of japonica element tolerating to photooxidation into the rice sterile line (maternal plant) is a breeding strategy worthy to pay great attention to.

Negative Effects of Oxytetracycline on Wheat (Triticum aestivum L.) Growth, Root Activity, Photosynthesis, and Chlorophyll Contents

A solution culture experiment was performed to investigate the effects of oxytetracycline （OTC） on wheat （Triticum aestivum L.） growth, chlorophyll contents, and photosynthesis at five levels of 0, 10, 20, 40, and 80 mmol L-1 OTC. OTC is toxic to wheat. The wheat growth, especially wheat root was significantly decreased. Further OTC also significantly decreased root activity, chlorophyll contents, and photosynthetic parameters except for intercellular CO2 concentrations. The different responses of indicators such as root number, root activity and so on to OTC were also observed. The IC50 values for the tested indicators to OTC ranged from 7.1 to 113.4 mmol L-1 OTC. The order of indicator sensitivity to OTC was root number stomatal conductance chlorophyll a total chlorophyll photosynthetic rates total surface area transpiration rate chlorophyll b fresh weight of root dry weight of root total length dry weight of shoot = fresh weight of shoot total volume. The root number was more sensitive than other indicators with the IC50 value of 7.1 mmol L-1 OTC, and could be taken as the sensitive indicator to predict the hazards of OTC to wheat.

Variable chlorophyll fluorescence in response to water plus heat stress treatments in three coniferous tree seedlings

Effects of water and heat stress treatments on chlorophyll fluorescence of Chinese fir (Cunninghamia lanceolata), Masson pine (Pinus massoniana) and western redcedar (Thuja plicata D. Don)_seedlings were monitored during a three-cycle stress period. It was shown that ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) of these three species responded differently to water stress treatments. The Fv/Fm ratio of western redcedar decreased dramatically after water stress, while that of Chinese fir had only a slight reduction and that of Masson pine had no significant change. The experiment also showed that the Fv/Fm ratio of all three species differed significantly under heat stress treatments. Concerning three different water plus heat stress cycles, it was found that the Fv/Fm ratios of Chinese fir and Masson pine measured at the end of each water plus heat stress cycle were not significantly different. However, the Fv/Fm ratio of western redcedar was diminished significantly in response to an increase of stress time. Keywords Chinese fir - Chlorophyll fluorescence - Heat stress - Masson pine - Water stress - Western redcedar CLC number Q945.17 - S791.248 Document code A Biography: Yu Fang-yuan (1965-), male, Ph. Doctor. Associate professor in College of Forest Resources and Environment, Nanjing, Forestry University, Nanjing 210037, P. R. China.Responsible editor: Zhu Hong

Heterogeneity of Chlorophyll Fluorescence of Phyllostachys edulis cv.Pachyloen Leaves

[Objective] This study aimed to explore the heterogeneity of chlorophyll flu- orescence of Phyllostachys edulis cv. Pachyloen leaves. [Method] Using the chloro- phyll fluorescence system and fluorescence imaging system in the Mini-IMAGING- PAM, the chlorophyll fluorescence of Phyllostachys edulis cv. Pachyloen leaves were measured and the fluorescence parameters were calculated. [Result] The homo- geneities of the maximal quantum yield of PS II （Fv/Fm） and the leaf absorptivity （Abs） were higher, with CVs （Coefficient of Variation） of 1.58%-1.68% and 1.75%- 2.12% respectively, while the heterogeneities of the actual quantum yield （Y）, non- photochemical quenching （NPQ/4）, photochemical quenching（qP） and relative photo- synthetic rate （PS/50） were higher, with CVs of 9.60%-14.23%, 10.23%-13.02%, 11.92%-13.02% and 11.15%-17.74% respectively. The trends of heterogeneity change in Y, qP and PSI50 were basically the same with transversely higher het- erogeneity at two sides and lower heterogeneity in the middle, namely with larger CVs at the edges of leaves and smaller ones around the midrib. Longitudinally, the coefficients of variation of Y, qP and PS/50 decreased gradually （from top to bot- tom）, which indicated that the heterogeneity declined from the leaf tip to the base. The trends of heterogeneity change in PS/50 and NPQ/4 were opposite. [Conclusion] The fluorescence parameters of Phyllostachys edulis cv. Pachyloen leaves revealed different heterogeneity.

Effects of NaCl Stress on Chlorophyll Fluorescence Parameters in Cinnamomum japonicum var. chenii

[ Objective ] Study on the changes of chlorophyll fluorescence parameters in Cinnamomumjaponicum var. chenii under NaCl stress. [ Method ] The seedling growth increment, chlorophyll content and chlorophyll fluorescence parameters in leaves of 1-year old Cinnamomum japonicum var. chenii were investigated in field experiment. [ Result] Under NaC1 stress, seedling growth increment reduced and the chlorophyll content decreased to a stable value ; changes of Fv/Fm and Fv/Fo showed identical increasing trend and double peak type. With the aggravation of salt stress, most variations were observed in Fo, correlations among chlorophyll fluorescence parameters presented ＂rise-drop＂ trend （in.the treatment of 7 g/L NaCl）. [ Conclusion] Cirmamomum japonicum vat. chenii is endowed with strong salt resistance and wide adaptability.

A New Global Solar-induced Chlorophyll Fluorescence(SIF)Data Product from TanSat Measurements

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.