Uniform Water Potential Induced by Salt, Alkali, and Drought Stresses Has Different Impacts on the Seedling of Hordeum jubatum: From Growth, Photosynthesis, and Chlorophyll Fluorescence

Hordeum jubatum is a halophyte ornamental plant wildly distributed in the Northeast of China, where the low water potential induced by various abiotic stresses is a major factor limiting plant growth and development. However, little is known about the comparative effects of salt, alkali, and drought stresses at uniform water potential on the plants. In the present study, the growth, gas exchange parameters, photosynthetic pigments, and chlorophyll fluorescence in the seedlings of H. jubatum under three low water potentials were measured. The results showed that the growth and photosynthetic parameters under these stresses were all decreased except for carotenoid (Car) with the increasing of stress concentration, and alkali stress caused the most damaging effects on the seedlings. The decreased net photosynthetic rate (Pn), stomatal conductance (Gs), and intercellular CO2 concentrations (Ci) values under salt stress were mainly attributed to stomatal factors, while non-stomatal factors were dominate under drought and alkali stresses. The reduced chlorophyll and slightly increased Car contents occurred under these stresses, and most significant changed under alkali stress. In addition, the maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), and photochemical quenching coefficient (qP) under the stresses were all decreased, indicating that salt, alkali, and drought stresses all increased susceptibility of PSII to photoinhibition, reduced the photosynthetic activity by the declined absorption of light for photochemistry, and increased PSII active reaction centers. Moreover, the non-photochemical quenching coefficient (NPQ) of alkali stress was different from salt and drought stresses, showing that the high pH of alkali stress caused more damaging effects on the photoprotection mechanism depending on the xanthophyll cycle. The above results suggest that the H. jubatum has stronger tolerance of salt than drought and alkali stresses, and the negative effects of alkali stress on the growth and photosynthetic performance of this species was most serious.

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Promoting pepper (Capsicum annuum) photosynthesis via chloroplast ultrastructure and enzyme activities by optimising the ammonium to nitrate ratio

Functional Plant Biology ◽

10.1071/fp19149 ◽

2020 ◽

Vol 47 (4) ◽

pp. 303

Author(s):

Jing Zhang ◽

Jianming Xie ◽

Yantai Gan ◽

Jeffrey A. Coulter ◽

Mohammed Mujitaba Dawuda ◽

...

Keyword(s):

Plant Growth ◽

Capsicum Annuum ◽

Photosynthetic Rate ◽

Large Subunit ◽

Photochemical Efficiency ◽

Chloroplast Ultrastructure ◽

Photochemical Quenching ◽

Gas Exchange Parameters ◽

Chilli Pepper ◽

N Assimilation

Optimal plant growth in many species is achieved when the two major forms of N are supplied at a particular ratio. In this pot experiment, the effects of five different ammonium:nitrate ratios (ANRs) (0:100, 12.5:87.5, 25:75, 37.5:62.5, and 50:50) on photosynthesis efficiency in chilli pepper (Capsicum annuum L.) plants were evaluated. The results showed that an ANR of 25:75 increased the contents of chl a, leaf area and dry matter, whereas chl b content was not affected by the ANRs. Regarding chlorophyll fluorescence, an ANR of 25:75 also enhanced the actual photochemical efficiency, photochemical quenching and maximum photosynthetic rate. However, the 0:100 and 50:50 ANRs resulted in higher values for nonphotochemical quenching. An inhibition of maximal photochemical efficiency was found when 50% NH4+ was supplied at the later stage of plant growth. The addition of 25% or 37.5% NH4+ was beneficial for gas exchange parameters and the 25% NH4+ optimised the thylakoid of chloroplasts. Compared with nitrate alone, 12.5–50% NH4+ upregulated glutamate dehydrogenase (GDH), the large subunit and the small subunit of Rubisco. It can be concluded that the 25:75 ANR accelerated N assimilation through active GDH, which provides a material basis for chloroplast and Rubisco formation, resulting in the increased photosynthetic rate and enhanced growth in chilli pepper.

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Bioaccumulation and changes in the photosynthetic apparatus of Prosopis juliflora exposed to copper

Botanical Sciences ◽

10.17129/botsci.507 ◽

2016 ◽

Vol 94 (2) ◽

pp. 323 ◽

Cited By ~ 2

Author(s):

Claudia Yared Michel-Lopez ◽

Francisco Espadas-Gil ◽

Gabriela Fuentes-Ortiz ◽

Jorge M. Santamaria ◽

Daniel González-Mendoza

Keyword(s):

Chlorophyll Fluorescence ◽

Photosystem Ii ◽

Photochemical Efficiency ◽

Photosynthetic Apparatus ◽

Copper Toxicity ◽

Photosynthetic Performance ◽

Prosopis Juliflora ◽

Copper Stress ◽

Short Term ◽

Chlorophyll Fluorescence Parameters

The effect of copper toxicity on the photosynthetic activities and bioaccumulation in different tissues of Prosopis juliflora was investigated using three CuSO4 concentrations (10, 50 and 100 mM) added under hydroponic conditions. Copper concentration and chlorophyll fluorescence were measured after 48 h of copper stress. The results obtained in this study show that increasing levels of 50 and 100 mM Cu2+ resulted in a significant accumulation of this metal mainly in roots compared with control roots. On the other hand, our result showed a significant reduction of maximum photochemical efficiency of photosystem II (Fv/Fm) and the activity of photosystem II (Fv/F0) ratios in P. juliflora leaf treated with 100 mM Cu2+ with respect to control after 4h of exposure. These changes suggested that the photosynthetic apparatus of P. juliflora was the primary target of the Cu2+ action. Therefore the information provided by this short-term (48 h) experiment in P. juliflora showed that several physiological processes are activated, in which the copper uptake by roots and their accumulation in tissues play a central role. In conclusion, the chlorophyll fluorescence parameters can be used as a useful physiological tool to assess early changes in photosynthetic performance of P. juliflora in response to copper pollution in short-term. Finally, the present study showed that P. juliflora is a promising prospect for heavy metals phytoremediation purposes occurring in arid and semi-arid climates in the northwest Mexico.

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EFFECT OF CHILLING STRESS ON THE PHOTOSYNTHETIC PERFORMANCE OF YOUNG PLANTS FROM TWO MAIZE (ZEA MAYS) HYBRIDS

CBU International Conference Proceedings ◽

10.12955/cbup.v5.1081 ◽

2017 ◽

Vol 5 ◽

pp. 1118-1123 ◽

Cited By ~ 2

Author(s):

Rositsa Cholakova-Bimbalova ◽

Andon Vassilev

Keyword(s):

Lipid Peroxidation ◽

Transition Period ◽

Chilling Stress ◽

Experimental Period ◽

Photosynthetic Performance ◽

Photochemical Quenching ◽

Photosynthetic Parameters ◽

Climate Conditions ◽

Maize Plants ◽

Non Photochemical Quenching

: In the climate conditions of Bulgaria, early stages of maize plants development often go under suboptimal temperatures. Chilling stress is known to cause different physiological disturbances in young maize plants during the transition period from heterotrophic to autotrophic nutrition. However, the effect of chilling may differ among maize hybrids. Photosynthetic performance could be a good indicator for the hybrid tolerance to chilling. The aim of our study was to evaluate the tolerance of young maize plants from two hybrids â€“ the new Bulgarian hybrid - Kneza 307 and the hybrid P9528 using as criteria the changes in their photosynthetic performance.Plants at the third leaf stage were exposed for seven days to chilling stress. At the end of the experimental period, growth, leaf lipid peroxidation, and several photosynthetic parameters were measured. We found that chilling stress reduced the fresh mass accumulation, increased lipid peroxidation, diminished net photosynthetic rate and chlorophyll content, and enhanced non-photochemical quenching of chlorophyll fluorescence. Although the responses of both hybrids were similar, some specificity were observed and discussed.

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Screening Pecan Cultivars for Drought Tolerance Using Physiological Parameters

HortScience ◽

10.21273/hortsci.40.4.1129d ◽

2005 ◽

Vol 40 (4) ◽

pp. 1129D-1129

Author(s):

Madhulika Sagaram ◽

Leonardo Lombardini

Keyword(s):

Abscisic Acid ◽

Chlorophyll Fluorescence ◽

Statistical Analysis ◽

Water Potential ◽

Block Design ◽

Weight Ratio ◽

Wide Distribution ◽

Leaf Water ◽

Gas Exchange Parameters ◽

Fluorescence Measurements

Pecan is a riparian species distributed over an area of geographic and climatic variation; such a wide distribution produces exposure to varied environmental conditions, providing a potential for genetic adaptation within the cultivars. Genotypes can be screened in order to obtain more drought tolerant cultivars using indirect screening parameters (chlorophyll fluorescence, osmotic adjustment, and abscisic acid assay) based on physiological responses of plants to abiotic stress conditions. A study was established at Texas A&M University, College Station, using a mixture of fritted clay (Quick dry) and pure sand in 1:1 (by weight) ratio to study the effects of drought on pecan rootstocks. The experiment was set up with the three water potential levels as treatments (–0.033 MPa, –0.1 MPa, –0.3 MPa) in a randomized complete-block design with three blocks. Measurements will include leaf water relations (relative water content, leaf water potential, osmotic adjustments, etc.), gas exchange parameters [net carbon dioxide assimilation rate (A), transpiration rate (E), stomatal conductance (gs)], chlorophyll fluorescence measurements [minimum (Fo), maximum (Fm), and variable fluorescence (Fv), quantum efficiency], water use efficiency, and abscisic acid assay on roots. Statistical analysis systems (SAS) package will be used for analysis. PROC GLM of the SAS will be used for statistical analysis of study involving plant response to water potential levels.

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Effects of Enhanced UV-B Radiation on the Drought Semi-deciduous Mediterranean Shrub Phlomis fruticosa under Field Conditions are Season-specific

Functional Plant Biology ◽

10.1071/pp9950737 ◽

1995 ◽

Vol 22 (5) ◽

pp. 737 ◽

Cited By ~ 20

Author(s):

D Nikolopoulos ◽

Y Petropoulou ◽

A Kyparissis ◽

Y Manetas

Keyword(s):

Developmental Stages ◽

Stratospheric Ozone ◽

Photochemical Efficiency ◽

Net Photosynthesis ◽

Experimental Period ◽

Dry Mass ◽

Photosynthetic Performance ◽

Photosynthetic Parameters ◽

Summer Drought ◽

Total Carotenoids

The effects of enhanced UV-B radiation on Phlomis fruticosa L. were recorded during a 1- year field study. Plants received ambient or ambient plus supplemental UV-B radiation (simulating a 15% stratospheric ozone depletion over Patras, 38.3�N, 29.1�E) and only natural precipitation, i.e. they were simultaneously exposed to other natural stresses, particularly water stress during summer. Actual, biologically equivalent UV-B doses were 8.55 and 11.21 kJ m-2 day-1 during the summer maximum (14 July) and 0.85 and 1.12 kJ m-2 day-1 during the winter minimum (27 December) for control and W-B plants respectively, while intermediate values were received for the rest of the year. lho seasonally separated effects could be distinguished. The first was a growth response, observed at late spring, in the absence of any simultaneous stress and at the period most favourable for this shrub, during which it shows maximum photosynthetic performance. The effect was an inhibition of new leaf development and premature falling of old leaves, leading to lower leaf numbers and total leaf areas for the rest of the experimental period. The second effect coincided with the summer drought, during which net photosynthesis, chlorophyll content and photochemical efficiency of photosystem II decreased in the controls, but a trend towards a further decrease in W-B irradiated plants was also evident. Changes in total carotenoids were negligible, leading to higher carotenoid to chlorophyll ratios under enhanced W-B radiation. Photosynthetic parameters recovered to the same levels in control and UV-B irradiated plants after the first heavy rains in autumn. At final harvest, considerable decreases in total dry mass were evident for UV-B irradiated plants, while plant height, UV-B-absorbing compounds, relative water content and leaf specific mass were unaffected during the whole experimental period. UV-B effects may depend not only on co-occumng natural stresses, but on the specific sensitivity of individual developmental stages as well, i.e. they may be season-specific.

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Exploring the scattering and reabsorption of chlorophyll fluorescence: implications for remote sensing of photosynthesis

10.5194/egusphere-egu2020-18194 ◽

2020 ◽

Author(s):

Karolina Sakowska ◽

Maria Pilar Cendrero-Mateo* ◽

Christiaan van der Tol ◽

Marco Celesti ◽

Giorgio Alberti ◽

...

Keyword(s):

Chlorophyll Fluorescence ◽

Heat Dissipation ◽

Structural Parameters ◽

Vegetation Indices ◽

Field Measurements ◽

Photosynthetic Performance ◽

Photochemical Quenching ◽

Spectral Vegetation Indices ◽

Leaf Level ◽

Scope Model

In recent years, technological progress in high-resolution field spectrometers have enabled the use of alternative tracer for constraining ecosystem-scale photosynthesis, i.e. sun-induced fluorescence (SIF). The principle underlying the use of SIF as a proxy of gross primary productivity (GPP) is based on the fact that the light energy absorbed by chlorophyll molecules can proceed into three different pathways: photochemistry, heat dissipation, and chlorophyll fluorescence. Since these processes directly compete for the same excitation energy, measurements of SIF and non-photochemical quenching (NPQ) are expected to provide information on photosynthetic performance.However, SIF signal measured at the leaf level or beyond is affected by several processes, including wavelength dependent scattering and reabsorption, which may need to be considered when linking SIF data and photosynthetic CO2 assimilation.To address this question, we conducted a multi-scale and multi-technique study that considered measurements of photosynthetic (GPP), optical (SIF, reflectance - R and transmittance - T), physiological (NPQ) and biophysical (the amount of absorbed photosynthetically active radiation - APAR) parameters of two soybean varieties: the MinnGold mutant, characterized by significantly reduced chlorophyll content (Chl), and the wild type, non-Chl deficient Eiko. We further used the &#8220;Soil-Canopy Observation Photosynthesis and Energy fluxes&#8221; (SCOPE) model to investigate the reabsorption and scattering of SIF. The measured leaf R, T and SIF and top-of-the-canopy R were used to retrieve biochemical and structural parameters of both varieties by inversion of the SCOPE model, while its forward mode was used to determine and correct for the scattering and reabsorption of SIF at both leaf and canopy level.Our study revealed that despite the large difference in Chl content (the ratio of Chl between MinnGold and Eiko was nearly 1:5), similar leaf and canopy photosynthesis rates were maintained in the Chl&#8208;deficient mutant. This phenomenon was captured neither by traditional spectral vegetation indices related to canopy greenness, nor by SIF measured in-situ. However, the modelling simulations revealed that when correcting for leaf and canopy scattering and reabsorption processes both varieties presented similar SIF yield (SIF/APAR). Furthermore, field measurements showed that APAR and NPQ in MinnGold were lower than in Eiko. This together explains the similar measured GPP and simulated SIF yield between the two varieties, and indicates that interpretation and application of SIF as a GPP tracer requires understanding and quantification of all these processes.

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Distinction and characterisation of rice genotypes tolerant to combined stresses of salinity and partial submergence, proved by a high-resolution chlorophyll fluorescence imaging system

Functional Plant Biology ◽

10.1071/fp18157 ◽

2019 ◽

Vol 46 (3) ◽

pp. 248 ◽

Cited By ~ 5

Author(s):

Bhubaneswar Pradhan ◽

Koushik Chakraborty ◽

Nibedita Prusty ◽

Deepa ◽

Arup Kumar Mukherjee ◽

...

Keyword(s):

Chlorophyll Fluorescence ◽

Quantum Yield ◽

Fluorescence Imaging ◽

Imaging System ◽

Oryza Sativa L ◽

Photochemical Efficiency ◽

Combined Effect ◽

Chlorophyll Fluorescence Imaging ◽

Photochemical Quenching ◽

Submergence Stress

Chlorophyll a fluorescence (ChlF) parameters measured with fluorescence imaging techniques were used to investigate the combined effect of salt and partial submergence stress to understand photosynthetic performance in rice (Oryza sativa L.). ChlF parameters such as maximal fluorescence (Fm), variable fluorescence (Fv=Fm –F0), the maximal photochemical efficiency of PSII (Fv/Fm) and the quantum yield of nonregulated energy dissipation of PSII (Y(NO)) were able to distinguish genotypes precisely based on their sensitivity to stress. Upon analysis, we found the images of F0 were indistinguishable among the genotypes, irrespective of their tolerance to salt and partial submergence stress. On the contrary, the images of Fm and Fv/Fm showed marked differences between the tolerant and susceptible genotypes in terms of tissue greenness and the appearance of dark spots as stress symptoms. The images of effective PSII quantum yield, the coefficient of nonphotochemical quenching (qN) and the coefficient of photochemical quenching (qP) captured under different PAR were able to distinguish the tolerant and susceptible genotypes, and were also quite effective for differentiating the tolerant and moderately tolerant ones. Similarly, the values of electron transport rate, qN, qP and Y(NO) were also able to distinguish the genotypes based on their sensitivity to stress. Overall, this investigation indicates the suitability of chlorophyll fluorescence imaging technique for precise phenotyping of rice based on their sensitivity to the combined effect of salt and partial submergence.

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Corrigendum to: Promoting pepper (Capsicum annuum) photosynthesis via chloroplast ultrastructure and enzyme activities by optimising the ammonium to nitrate ratio

Functional Plant Biology ◽

10.1071/fp19149_co ◽

2020 ◽

Vol 47 (5) ◽

pp. 473

Author(s):

Jing Zhang ◽

Jianming Xie ◽

Yantai Gan ◽

Jeffrey A. Coulter ◽

Mohammed Mujitaba Dawuda ◽

...

Keyword(s):

Plant Growth ◽

Capsicum Annuum ◽

Photosynthetic Rate ◽

Large Subunit ◽

Photochemical Efficiency ◽

Chloroplast Ultrastructure ◽

Photochemical Quenching ◽

Gas Exchange Parameters ◽

Chilli Pepper ◽

N Assimilation

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Determining Freezing Injury from Changes in Chlorophyll Fluorescence in Potted Oleander Plants

HortScience ◽

10.21273/hortsci.46.6.895 ◽

2011 ◽

Vol 46 (6) ◽

pp. 895-900 ◽

Cited By ~ 4

Author(s):

Julián Miralles-Crespo ◽

Juan Antonio Martínez-López ◽

José Antonio Franco-Leemhuis ◽

Sebastián Bañón-Arias

Keyword(s):

Chlorophyll Fluorescence ◽

Chilling Stress ◽

Photochemical Efficiency ◽

Freezing Injury ◽

Photochemical Quenching ◽

Biochemical Indicators ◽

Freezing Temperatures ◽

Non Photochemical Quenching ◽

Maximum Photochemical Efficiency ◽

Physiological And Biochemical

Physiological and biochemical indicators that reflect the responses of plants to chilling stress could be useful for identifying plant damage caused by freezing or other stresses. The objective of this study was to determine any relationship between changes in chlorophyll fluorescence and the appearance of visual symptoms resulting from freezing temperatures in two cultivars of oleander. In the least frost-sensitive cultivar (yellow oleander), freezing temperatures (–4 °C for 3 h) did not produce changes in the photochemical parameters. In the more frost-sensitive cultivar (pink oleander), non-photochemical quenching (NPQ) and the maximum photochemical efficiency of photosystem II (Fv/Fm) decreased after the same freezing treatment. The first of these potential indicators remained low, whereas the second steadily recovered during the 4 months after freezing simulation. The results suggest that measuring chlorophyll fluorescence may provide a rapid method for assessing freezing injury in oleander.

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Salinity effects on chloroplast PSII performance in glycophytes and halophytes

Functional Plant Biology ◽

10.1071/fp16135 ◽

2016 ◽

Vol 43 (11) ◽

pp. 1003 ◽

Cited By ~ 13

Author(s):

William J. Percey ◽

Andrew McMinn ◽

Jayakumar Bose ◽

Michael C. Breadmore ◽

Rosanne M. Guijt ◽

...

Keyword(s):

Critical Role ◽

Photochemical Efficiency ◽

Chenopodium Quinoa ◽

Nacl Stress ◽

Photosynthetic Performance ◽

K Channel ◽

Photosynthetic Parameters ◽

Atpase Inhibitor ◽

Mesophyll Cells ◽

Isolated Chloroplasts

The effects of NaCl stress and K+ nutrition on photosynthetic parameters of isolated chloroplasts were investigated using PAM fluorescence. Intact mesophyll cells were able to maintain optimal photosynthetic performance when exposed to salinity for more than 24 h whereas isolated chloroplasts showed declines in both the relative electron transport rate (rETR) and the maximal photochemical efficiency of PSII (Fv/Fm) within the first hour of treatment. The rETR was much more sensitive to salt stress compared with Fv/Fm, with 40% inhibition of rETR observed at apoplastic NaCl concentration as low as 20 mM. In isolated chloroplasts, absolute K+ concentrations were more essential for the maintenance of the optimal photochemical performance (Fv/Fm values) rather than sodium concentrations per se. Chloroplasts from halophyte species of quinoa (Chenopodium quinoa Willd.) and pigface (Carpobrotus rosii (Haw.) Schwantes) showed less than 18% decline in Fv/Fm under salinity, whereas the Fv/Fm decline in chloroplasts from glycophyte pea (Pisum sativum L.) and bean (Vicia faba L.) species was much stronger (31 and 47% respectively). Vanadate (a P-type ATPase inhibitor) significantly reduced Fv/Fm in both control and salinity treated chloroplasts (by 7 and 25% respectively), whereas no significant effects of gadolinium (blocker of non-selective cation channels) were observed in salt-treated chloroplasts. Tetraethyl ammonium (TEA) (K+ channel inhibitor) and amiloride (inhibitor of the Na+/H+ antiporter) increased the Fv/Fm of salinity treated chloroplasts by 16 and 17% respectively. These results suggest that chloroplasts’ ability to regulate ion transport across the envelope and thylakoid membranes play a critical role in leaf photosynthetic performance under salinity.

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