scholarly journals Interspecific differences in photosynthetic efficiency and spectral reflectance in two Umbilicaria species from Svalbard during controlled desiccation

2012 ◽  
Vol 2 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Radek Jupa ◽  
Josef Hájek ◽  
Jana Hazdrová ◽  
Miloš Barták
Keyword(s):  
Spectral Reflectance ◽  
Initial Phase ◽  
Photosynthetic Efficiency ◽  
Higher Plants ◽  
Photosynthetic Performance ◽  
Curvilinear Relationship ◽  
Photochemical Reflectance Index ◽  
Interspecific Differences ◽  
Shape Curve ◽  
Poikilohydric Organisms

This study aimed to evaluate the effective photosynthetic quantum yield (FPSII) and the Photochemical Reflectance Index (PRI) for assessment of photosynthetic performance of two Umbilicaria lichens during gradual desiccation of their thalli. U. cylindrica andU. decussata exhibited curvilinear relationship (S-shape curve) of decreasing FPSII values with decreasing water potential (WP) of thalli. During initial phase of desiccation (WP from 0 to -10 MPa), no decrease of FPSII was apparent, further desiccation (WP from -10 to -20 MPa) led to fast FPSII decrease from 0.6 to 0.1 indicating strong inhibition of photosynthetic processes. Critical WP at which photosythetic processes are fully inhibited was found bellow -25 MPa in both lichen species. Photochemical Reflectance Index (PRI) exhibited curvilinear increase with thalli desiccation (decreasing WP). At full thallus hydration, the PRI reached the value of -0.18 in both species. Under strong dehydration (WP from -20 to -30 MPa), however, U. cylindrica showed somewhat lower value (-0.04) than U.decussata (-0.02 MPa). PRI to WP relationship is discussed and compared to existing evidence from higher plants and poikilohydric organisms.

scholarly journals Altering Tetrapyrrole Biosynthesis by Overexpressing Ferrochelatases (Fc1 and Fc2) Improves Photosynthetic Efficiency in Transgenic Barley

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1370
Author(s):  
Dilrukshi S. K. Nagahatenna ◽  
Jingwen Tiong ◽  
Everard J. Edwards ◽  
Peter Langridge ◽  
Ryan Whitford
Keyword(s):  
Stomatal Conductance ◽  
Photosynthetic Efficiency ◽  
Catalytic Domain ◽  
Growth Conditions ◽  
Photosynthetic Performance ◽  
Tetrapyrrole Biosynthesis ◽  
Hordeum Vulgare L ◽  
Yield Performance ◽  
Photosynthetic Organisms ◽  
Transgenic Barley

Ferrochelatase (FC) is the terminal enzyme of heme biosynthesis. In photosynthetic organisms studied so far, there is evidence for two FC isoforms, which are encoded by two genes (FC1 and FC2). Previous studies suggest that these two genes are required for the production of two physiologically distinct heme pools with only FC2-derived heme involved in photosynthesis. We characterised two FCs in barley (Hordeum vulgare L.). The two HvFC isoforms share a common catalytic domain, but HvFC2 additionally contains a C-terminal chlorophyll a/b binding (CAB) domain. Both HvFCs are highly expressed in photosynthetic tissues, with HvFC1 transcripts also being abundant in non-photosynthetic tissues. To determine whether these isoforms differentially affect photosynthesis, transgenic barley ectopically overexpressing HvFC1 and HvFC2 were generated and evaluated for photosynthetic performance. In each case, transgenics exhibited improved photosynthetic rate (Asat), stomatal conductance (gs) and carboxylation efficiency (CE), showing that both FC1 and FC2 play important roles in photosynthesis. Our finding that modified FC expression can improve photosynthesis up to ~13% under controlled growth conditions now requires further research to determine if this can be translated to improved yield performance under field conditions.

Photosynthetic efficiency of northern forest ecosystems using a MODIS-derived Photochemical Reflectance Index (PRI)

2016 ◽  
Vol 187 ◽  
pp. 345-366 ◽  
Author(s):  
E.M. Middleton ◽  
K.F. Huemmrich ◽  
D.R. Landis ◽  
T.A. Black ◽  
A.G. Barr ◽  
...  
Keyword(s):  
Photosynthetic Efficiency ◽  
Forest Ecosystems ◽  
Northern Forest ◽  
Photochemical Reflectance Index

scholarly journals Spectral reflectance indices sense desiccation induced changes in the thalli of Antarctic lichen Dermatocarpon polyphyllizum

2018 ◽  
Vol 8 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Miloš Barták ◽  
Kumud Bandhu Mishra ◽  
Michaela Marečková
Keyword(s):  
Spectral Reflectance ◽  
Vegetation Index ◽  
Near Infrared ◽  
Normalized Difference Vegetation Index ◽  
Spectral Characteristics ◽  
Structural Features ◽  
Coefficient Of Determination ◽  
Curvilinear Relationship ◽  
Structural Deterioration ◽  
Reflectance Indices

Lichens, in polar and alpine regions, pass through repetitive dehydration and rehydration events over the years. The harsh environmental conditions affect the plasticity of lichen’s functional and structural features for their survival, in a species-specific way, and, thus, their optical and spectral characteristics. For an understanding on how dehydration affects lichens spectral reflectance, we measured visible (VIS) and near infrared (NIR) reflectance spectra of Dermatocarpon polyphyllizum, a foliose lichen species, from James Ross Island (Antarctica), during gradual dehydration from fully wet (relative water content (RWC) = 100%) to dry state (RWC = 0%), under laboratory conditions, and compared several derived reflectance indices (RIs) to RWC. We found a curvilinear relationship between RWC and range of RIs: water index (WI), photochemical reflectance index (PRI), normalized difference vegetation index (NDVI), modified chlorophyll absorption in reflectance indices (MCARI and MCARI1), simple ratio pigment index (SRPI), normalized pigment chlorophyll index (NPCI), and a new NIR shoulder region spectral ratio index (NSRI). The index NDVI was initially increased with maxima around 70% RWC and it steadily declined with further desiccation, whereas PRI in-creased with desiccation and steeply falls when RWC was below 10%. The curvilinear relationship, for RIs versus RWC, was best fitted by polynomial regressions of second or third degree, and it was found that RWC showed very high correlation with WI (R2 = 0.94) that is followed by MCARI (R2 = 0.87), NDVI (R2 = 0.83), and MCARI (R2 = 0.81). The index NSRI, proposed for accessing structural deterioration, was almost invariable during dehydration with the least value of the coefficient of determination (R2 = 0.28). This may mean that lichen, Dermatocarpon polyphyllizum, activates protection mechanisms initially in response to the progression of dehydration; however, severe dehydration causes deactivation of photosynthesis and associated pigments without much affecting its structure.

scholarly journals Demonstration of a relationship between state transitions and photosynthetic efficiency in a higher plant

2019 ◽  
Vol 476 (21) ◽  
pp. 3295-3312 ◽  
Author(s):  
Craig R. Taylor ◽  
Wim van Ieperen ◽  
Jeremy Harbinson
Keyword(s):  
Photosynthetic Efficiency ◽  
State Transition ◽  
Higher Plants ◽  
Photosynthetic Apparatus ◽  
State Transitions ◽  
Short Term ◽  
Higher Plant ◽  
Series Configuration ◽  
Use Efficiency ◽  
Sun And Shade

A consequence of the series configuration of PSI and PSII is that imbalanced excitation of the photosystems leads to a reduction in linear electron transport and a drop in photosynthetic efficiency. Achieving balanced excitation is complicated by the distinct nature of the photosystems, which differ in composition, absorption spectra, and intrinsic efficiency, and by a spectrally variable natural environment. The existence of long- and short-term mechanisms that tune the photosynthetic apparatus and redistribute excitation energy between the photosystems highlights the importance of maintaining balanced excitation. In the short term, state transitions help restore balance through adjustments which, though not fully characterised, are observable using fluorescence techniques. Upon initiation of a state transition in algae and cyanobacteria, increases in photosynthetic efficiency are observable. However, while higher plants show fluorescence signatures associated with state transitions, no correlation between a state transition and photosynthetic efficiency has been demonstrated. In the present study, state 1 and state 2 were alternately induced in tomato leaves by illuminating leaves produced under artificial sun and shade spectra with a sequence of irradiances extreme in terms of PSI or PSII overexcitation. Light-use efficiency increased in both leaf types during transition from one state to the other with remarkably similar kinetics to that of F′m/Fm, F′o/Fo, and, during the PSII-overexciting irradiance, ΦPSII and qP. We have provided compelling evidence for the first time of a correlation between photosynthetic efficiency and state transitions in a higher plant. The importance of this relationship in natural ecophysiological contexts remains to be elucidated.

scholarly journals Rapid and Positive Effect of Bicarbonate Addition on Growth and Photosynthetic Efficiency of the Green Microalgae Chlorella Sorokiniana (Chlorophyta, Trebouxiophyceae)

2020 ◽  
Vol 10 (13) ◽  
pp. 4515 ◽  
Author(s):  
Giovanna Salbitani ◽  
Francesco Bolinesi ◽  
Mario Affuso ◽  
Federica Carraturo ◽  
Olga Mangoni ◽  
...  
Keyword(s):  
Photosynthetic Efficiency ◽  
Inorganic Carbon ◽  
Primary Source ◽  
Photosynthetic Performance ◽  
Chlorella Sorokiniana ◽  
Algal Culture ◽  
Short Term ◽  
Bicarbonate Ions ◽  
Short Period ◽  
Positive Effect

Bicarbonate ions are the primary source of inorganic carbon for autotrophic organisms living in aquatic environments. In the present study, we evaluated the short-term (hours) effects of sodium bicarbonate (NaHCO3) addition on the growth and photosynthetic efficiency of the green algae Chlorella sorokiniana (211/8k). Bicarbonate was added to nonaxenic cultures at concentrations of 1, 2, and 3 g L−1 leading to a significant increase in biomass especially at the highest salt concentration (3 g L−1) and also showing a bactericidal and bacteriostatic effect that helped to keep a reduced microbial load in the algal culture. Furthermore, bicarbonate stimulated the increase in cellular content of chlorophyll a, improving the photosynthetic performance of cells. Since microalgae of genus Chlorella spp. show great industrial potential for the production of biofuels, nutraceuticals, cosmetics, health, and dietary supplements and the use of bicarbonate as a source of inorganic carbon led to short-term responses in Chlorella sorokiniana, this method represents a valid alternative not only to the insufflation of carbon dioxide for the intensive cultures but also for the production of potentially bioactive compounds in a short period.

scholarly journals Blue Light Improves Photosynthetic Performance during Healing and Acclimatization of Grafted Watermelon Seedlings

2021 ◽  
Vol 22 (15) ◽  
pp. 8043
Author(s):  
Moein Moosavi-Nezhad ◽  
Reza Salehi ◽  
Sasan Aliniaeifard ◽  
Georgios Tsaniklidis ◽  
Ernst J. Woltering ◽  
...  
Keyword(s):  
Leaf Area ◽  
Chlorophyll Content ◽  
Photosynthetic Efficiency ◽  
Seedling Survival ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Performance ◽  
Soluble Carbohydrate ◽  
Survival Ratio ◽  
Promoting Effect ◽  
Photosynthetic Properties

To investigate the importance of light on healing and acclimatization, in the present study, grafted watermelon seedlings were exposed to darkness (D) or light, provided by blue (B), red (R), a mixture of R (68%) and B (RB), or white (W; 35% B, 49% intermediate spectra, 16% R) LEDs for 12 days. Survival ratio, root and shoot growth, soluble carbohydrate content, photosynthetic pigments content, and photosynthetic performance were evaluated. Seedling survival was not only strongly limited in D but the survived seedlings had an inferior shoot and root development, reduced chlorophyll content, and attenuated photosynthetic efficiency. RB-exposed seedlings had a less-developed root system. R-exposed seedlings showed leaf epinasty, and had the smallest leaf area, reduced chlorophyll content, and suppressed photosynthetic apparatus performance. The R-exposed seedlings contained the highest amount of soluble carbohydrate and together with D-exposed seedlings the lowest amount of chlorophyll in their scions. B-exposed seedlings showed the highest chlorophyll content and improved overall PSII photosynthetic functioning. W-exposed seedling had the largest leaf area, and closely resembled the photosynthetic properties of RB-exposed seedlings. We assume that, during healing of grafted seedlings monochromatic R light should be avoided. Instead, W and monochromatic B light may be willingly adopted due to their promoting effect on shoot, pigments content, and photosynthetic efficiency.

Infrared Emittance and Electrical Properties of Ce4+ Doped Sm0.5Sr0.5CoO3 Ceramics

2019 ◽  
Vol 294 ◽  
pp. 45-50
Author(s):  
Le Chen ◽  
Wang Zhan ◽  
Hui Min Sun ◽  
Zhao Zhan Gu
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Spectral Reflectance ◽  
Initial Phase ◽  
Solid State Reaction Method ◽  
Thermal Conversion ◽  
Reaction Method ◽  
Radiation Properties ◽  
Opening Up ◽  
Conductivity Behavior

A series of Sm0.5Sr0.5CoO3-CeO2 ceramics formed by solid state-reaction method have been systematically investigated. The effects of doping the Sm site of Sm0.5Sr0.5CoO3 with Ce4+ on the structural, spectral reflectance, and thermal radiation properties were also explored. The modification of the initial phase takes place can be ascribed to the dissolution of Ce from initial CeO2 into the perovskite structure. The conductivity behavior depends critically on the Ce doping level, as was demonstrated that the recombination of holes (from Sm0.5Sr0.5CoO3) and electrons (from ceria ion) could decrease electrical conductivity. Sm0.5Sr0.5CoO3-CeO2 ceramics showed continuously adjustable conductivity and infrared emittance, opening up possible applications in solar thermal conversion or thermosensitive conductivity.

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