Chlorophyll fluorescence of submerged and floating leaves of the aquatic resurrection plant Chamaegigas intrepidus

2004 ◽  
Vol 31 (1) ◽  
pp. 53 ◽  
Author(s):  
Markus Woitke ◽  
Wolfram Hartung ◽  
Hartmut Gimmler ◽  
Hermann Heilmeier
Keyword(s):  
Chlorophyll Fluorescence ◽  
Shade Tolerance ◽  
Photosynthetic Performance ◽  
Resurrection Plant ◽  
Photon Flux ◽  
Carbon Gain ◽  
Light Conditions ◽  
Total Plant ◽  
Floating Leaves

The role of submerged and floating leaves in plant photosynthetic performance of the aquatic resurrection plant Chamaegigas intrepidus Dinter was investigated by monitoring chlorophyll fluorescence under the fluctuating natural field conditions that characterise the extreme habitat of this species. The performance of the two different leaf types during desiccation–rehydration cycles in the field was examined. PSII quantum efficiency indicates a similar regeneration capacity in both leaf types after water stress. Electron transport rates under controlled light conditions were 3–4 times higher in floating leaves than in submerged leaves. The two leaf types showed specific adaptations to their ambient photosynthetic photon flux densities (PPFD), shade tolerance in the submerged leaves and adaptation to high PPFD in floating leaves. These results imply a significant role of the floating leaves for total plant carbon gain. It is concluded that the combination of high N content of floating leaves and a high availability of CO2 and light at the water surface contributes to the importance of this leaf type for photosynthesis in C. intrepidus.

The Role of D 1* in Light-Induced D 1 Protein Turnover in Leaves

1993 ◽  
Vol 48 (3-4) ◽  
pp. 246-250
Author(s):  
Anna J. Syme ◽  
Harald R . Bolhàr-N ordenkampf ◽  
Christa Critchley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Light Intensity ◽  
Protein Turnover ◽  
Photochemical Efficiency ◽  
Light Conditions ◽  
Ps Ii ◽  
Light Intensities ◽  
Intact Leaves

Abstract Light-induced degradation of the D 1 protein of photosystem II (PS II) was determined by radioactive pulse-chase labelling experiments in intact leaves of Schefflera polybotrya. PS II photochemical efficiency was monitored by measuring chlorophyll fluorescence. A significant and consistent decline in the Fv/ Fm ratio was taken to indicate photoinhibition. The formation and degradation of a modified form of the D 1 protein, D 1*, was different under photoinhibi-tory or non-photoinhibitory light conditions. At photoinhibitory irradiance greater amounts of D 1 * were formed relative to D 1, and the degradation of D 1* was slower when compared with non-photoinhibitory irradiance. The formation and degradation of D 1* were therefore shown to be at least partly light intensity dependent. Higher light intensities appeared to slow D 1* degradation, which suggests a modification in PS II turnover properties.

Growth, Morphology, and Physiology of Intsia bijuga Trees Under Varied Light Conditions

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 480c-480
Author(s):  
Robin A. DeMeo ◽  
Thomas E. Marler
Keyword(s):  
Shade Tolerance ◽  
Light Exposure ◽  
Dark Respiration ◽  
Stomatal Density ◽  
Seedling Emergence ◽  
Sunlight Exposure ◽  
Photon Flux ◽  
Light Conditions ◽  
Plant Characteristics ◽  
Growth Differences

Six studies were conducted with Intsia bijuga seedlings to determine the methods and extent of shade tolerance for this species. Growth differences were minimal among plants receiving varied light exposure, although treatments ranged from 19% to 100% sunlight exposure. Light saturated photosynthesis of leaves on plants receiving 24% sunlight was achieved at a photosynthetic photon flux (PPF) of about one-fourth of that for the leaves on plants receiving 100% sunlight exposure. However, photosynthesis under conditions of extremely low PPF was higher for shade-grown plants than for full-sun plants. Shaded plants exhibited lower dark respiration, light compensation point, and light-saturated photosynthesis than full sun plants. Leaflet thickness, palisade layer number, and stomatal density of leaves of shaded plants were reduced compared with full sun plants. At seedling emergence and for several months thereafter, the plants responded to shade primarily with obligate sun plant characteristics. After the plants were established, however, responses to the varied light conditions indicated facultative structural and physiological characteristics.

Leaf acclimation strategies to contrasting light conditions in saplings of different shade tolerance in a tropical cloud forest

2018 ◽  
Vol 45 (9) ◽  
pp. 968 ◽  
Author(s):  
Ana Quevedo-Rojas ◽  
Carlos García-Núñez ◽  
Mauricio Jerez-Rico ◽  
Ramón Jaimez ◽  
Teresa Schwarzkopf
Keyword(s):  
Optical Properties ◽  
Shade Tolerance ◽  
Light Exposure ◽  
Cloud Forest ◽  
Repeated Measurements ◽  
Photon Flux ◽  
Light Conditions ◽  
Light Gradient ◽  
Tolerant Species ◽  
Shade Tolerant Species

To study the acclimation responses of the leaves of saplings of six tree species when changed to low or high levels of irradiance, we carried out a light exposure experiment. Species representative of contrasting shade tolerance groups were identified across a light gradient in the understorey of a Venezuelan Andean cloud forest. Measured traits included gas exchange, chlorophyll fluorescence, and morphoanatomical, biochemical and optical properties. Saplings were grown for 6 months in a shade-house receiving 20% photosynthetic photon flux (PPF) of full sunlight. Plant samples were then moved to shade-houses receiving low PPF (4%) or high PPF (65%). A factorial model (species × PPF), with repeated measurements (0, 15 and 120 days) was designed. Our results showed that morphological and anatomical traits were more plastic to PPF changes than photosynthetic traits. All species were susceptible to photoinhibition (15 days): shade-intolerant species showed dynamic photoinhibition (120 days), whereas shade-tolerant species presented chronic photoinhibition and the consequent inability to increase C assimilation rates under high PPF. The partially shade-tolerant species showed mixed responses; nonetheless, they exhibited larger adjustments in morphoanatomical and optical properties. Thus the acclimation responses of these species when subject to contrasting light conditions could help to explain their distribution along the light gradient in the understorey.

scholarly journals The Role of La2O3 in Enhancement the Radiation Shielding Efficiency of the Tellurite Glasses: Monte-Carlo Simulation and Theoretical Study

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3913
Author(s):  
Aljawhara H. Almuqrin ◽  
Mohamed Hanfi ◽  
K. G. Mahmoud ◽  
M. I. Sayyed ◽  
Hanan Al-Ghamdi ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Theoretical Study ◽  
Radiation Shielding ◽  
Photon Flux ◽  
Transmission Factor ◽  
Tellurite Glasses ◽  
Attenuation Coefficients ◽  
Binary Glass ◽  
Buildup Factors

The radiation shielding competence was examined for a binary glass system xLa2O3 + (1 − x) TeO2 where x = 5, 7, 10, 15, and 20 mol% using MCNP-5 code. The linear attenuation coefficients (LACs) of the glasses were evaluated, and it was found that LT20 glass has the greatest LAC, while LT5 had the least LAC. The transmission factor (TF) of the glasses was evaluated against thicknesses at various selected energies and was observed to greatly decrease with increasing thickness; for example, at 1.332 MeV, the TF of the LT5 glass decreased from 0.76 to 0.25 as the thickness increased from 1 to 5 cm. The equivalent atomic number (Zeq) of the glasses gradually increased with increasing photon energy above 0.1 MeV, with the maximum values observed at around 1 MeV. The buildup factors were determined to evaluate the accumulation of photon flux, and it was found that the maximum values for both can be seen at around 0.8 MeV. This research concluded that LT20 has the greatest potential in radiation shielding applications out of the investigated glasses due to the glass having the most desirable parameters.

scholarly journals The Role of Selected Wavelengths of Light in the Activity of Photosystem II in Gloeobacter violaceus

2021 ◽  
Vol 22 (8) ◽  
pp. 4021
Author(s):  
Monika Kula-Maximenko ◽  
Kamil Jan Zieliński ◽  
Ireneusz Ślesak
Keyword(s):  
Photosystem Ii ◽  
Spectral Composition ◽  
Photosynthetic Electron Transport ◽  
Metabolic Energy ◽  
Light Conditions ◽  
Gloeobacter Violaceus ◽  
Transport Chain ◽  
Cyanobacterial Culture ◽  
Photosynthetic Antennas

Gloeobacter violaceus is a cyanobacteria species with a lack of thylakoids, while photosynthetic antennas, i.e., phycobilisomes (PBSs), photosystem II (PSII), and I (PSI), are located in the cytoplasmic membrane. We verified the hypothesis that blue–red (BR) light supplemented with a far-red (FR), ultraviolet A (UVA), and green (G) light can affect the photosynthetic electron transport chain in PSII and explain the differences in the growth of the G. violaceus culture. The cyanobacteria were cultured under different light conditions. The largest increase in G. violaceus biomass was observed only under BR + FR and BR + G light. Moreover, the shape of the G. violaceus cells was modified by the spectrum with the addition of G light. Furthermore, it was found that both the spectral composition of light and age of the cyanobacterial culture affect the different content of phycobiliproteins in the photosynthetic antennas (PBS). Most likely, in cells grown under light conditions with the addition of FR and G light, the average antenna size increased due to the inactivation of some reaction centers in PSII. Moreover, the role of PSI and gloeorhodopsin as supplementary sources of metabolic energy in the G. violaceus growth is discussed.

Quantifying high‐temperature stress on soybean canopy photosynthesis: The unique role of sun‐induced chlorophyll fluorescence

2021 ◽  
Author(s):  
Hyungsuk Kimm ◽  
Kaiyu Guan ◽  
Charles H. Burroughs ◽  
Bin Peng ◽  
Elizabeth A. Ainsworth ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
High Temperature ◽  
Temperature Stress ◽  
High Temperature Stress ◽  
Canopy Photosynthesis ◽  
Unique Role ◽  
Soybean Canopy

scholarly journals Hormonal and Hydroxycinnamic Acids Profiles in Banana Leaves in Response to Various Periods of Water Stress

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jalel Mahouachi ◽  
María F. López-Climent ◽  
Aurelio Gómez-Cadenas
Keyword(s):  
Water Stress ◽  
Leaf Gas Exchange ◽  
Stomatal Closure ◽  
Photosynthetic Performance ◽  
Hydroxycinnamic Acids ◽  
Cinnamic Acids ◽  
Gas Exchange Parameters ◽  
Banana Leaves ◽  
Indole 3 Acetic Acid

The pattern of change in the endogenous levels of several plant hormones and hydroxycinnamic acids in addition to growth and photosynthetic performance was investigated in banana plants (Musa acuminatacv. “Grand Nain”) subjected to various cycles of drought. Water stress was imposed by withholding irrigation for six periods with subsequent rehydration. Data showed an increase in abscisic acid (ABA) and indole-3-acetic acid (IAA) levels, a transient increase in salicylic acid (SA) concentration, and no changes in jasmonic acid (JA) after each period of drought. Moreover, the levels of ferulic (FA) and cinnamic acids (CA) were increased, and plant growth and leaf gas exchange parameters were decreased by drought conditions. Overall, data suggest an involvement of hormones and hydroxycinnamic acids in plant avoidance of tissue dehydration. The increase in IAA concentration might alleviate the senescence of survival leaves and maintained cell elongation, and the accumulation of FA and CA could play a key role as a mechanism of photoprotection through leaf folding, contributing to the effect of ABA on inducing stomatal closure. Data also suggest that the role of SA similarly to JA might be limited to a transient and rapid increase at the onset of the first period of stress.

The role of resonance radiation in the propagation of a positive pre-breakdown ionization wave in long discharge tubes

2021 ◽  
Author(s):  
Aleksei V Siasko ◽  
Yuri B Golubovskii ◽  
Sergei Valin
Keyword(s):  
Discharge Tube ◽  
Tube Wall ◽  
Finite Size ◽  
Ionization Wave ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Radiation Trapping ◽  
Discharge Tubes ◽  
Electron Photoemission

Abstract The work is devoted to calculating the flux of resonance photons towards the boundary of a cylindrical discharge tube of a finite size during the propagation of a pre-breakdown ionization wave of positive polarity. A cylindrical discharge tube of finite dimensions with argon at the pressure of p=1 Torr is considered. The propagation mechanisms of metastable and resonance atoms are compared. For the considered discharge conditions, the space-time distributions of metastable and resonance atoms are calculated. The manuscript presents a technique for calculating the flux of resonance photons onto the discharge tube wall with the account of the radiation trapping. It is shown that for the studied conditions the photon flux density towards the longitudinal boundary of the tube ahead of the ionization wave can reach 1013 cm-2s-1. The obtained results allow describing the appearance of seed electrons ahead of the positive ionization wavefront during its propagation due to the electron photoemission from the discharge tube wall.

scholarly journals Effects of NaCl and CaCl2 Salinization on Morpho-Anatomical and Physiological Traits of Potted Callistemon citrinus Plants

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1666
Author(s):  
Veronica De Micco ◽  
Carmen Arena ◽  
Chiara Amitrano ◽  
Youssef Rouphael ◽  
Stefania De Pascale ◽  
...  
Keyword(s):  
Structural Damage ◽  
Leaf Gas Exchange ◽  
Fluorescence Emission ◽  
Photosynthetic Performance ◽  
Saline Stress ◽  
Close Relationship ◽  
Osmotic Solution ◽  
Physiological Acclimation ◽  
Anatomical Parameters

The aim of this work was to assess the possible coordination mechanisms between leaf functional anatomical traits and physiological acclimation of potted Callistemon citrinus plants when subjected to two saline iso-osmotic solutions using NaCl or CaCl2. Digital image analysis was applied to quantify anatomical parameters with a specific focus on the occurrence of signs of structural damage as well as on alterations, such as the occurrence of shrunk tissues and accumulation of phenolic compounds. Morpho-anatomical analyses were accompanied by measurements of leaf gas exchange and chlorophyll fluorescence emission. Results showed that C. citrinus plants, when irrigated with the CaCl2 solution, induced a leaf morpho-anatomical structure which did not allow the maintenance of high photosynthetic performance under such conditions, compared to both controls and plants treated with the iso-osmotic solution of NaCl. Data collected seem to suggest a close relationship between anatomical traits and eco-physiological strategies in maintaining the photosynthetic efficiency under saline stress conditions and highlight the fundamental role of leaf anatomy in imposing the limits of plant physiology.

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