Fv/Fm acclimation to the Mediterranean summer drought in two sympatric Lasallia species from the Iberian mountains

2017 ◽  
Vol 49 (2) ◽  
pp. 157-165 ◽  
Author(s):  
M. VIVAS ◽  
S. PÉREZ-ORTEGA ◽  
A. PINTADO ◽  
L. G. SANCHO
Keyword(s):  
Temporal Variation ◽  
Quantum Efficiency ◽  
Physiological State ◽  
Photosynthetic Apparatus ◽  
Weather Conditions ◽  
Photosynthetic Performance ◽  
Summer Drought ◽  
Field Site ◽  
Central Spain ◽  
Lasallia Pustulata

AbstractPhotosynthetic performance in lichens can vary throughout the year. We investigate the variation in the PSII quantum efficiency as a proxy for the physiological state of the photosynthetic apparatus in two umbilicate species from the genus Lasallia. Temporal variation in Fv/Fm in both species was monitored at a field site in Central Spain where both species coexist. Subsequent measurements were carried out in the laboratory after 48 h preconditioning. Both species showed clear variation during the year in PSII performance, with a marked depression in Fv/Fm during the summer. Lasallia pustulata consistently had higher Fv/Fm values than L. hispanica. Both species reached higher Fv/Fm values after 48 h of preconditioning in the laboratory and this recovery was particularly notable in the summer months. Fv/Fm was highly related to antecedent weather conditions during the two days prior to measurement.

scholarly journals Phytotoxicity of Silver Nanoparticles on Tobacco Plants: Evaluation of Coating Effects on Photosynthetic Performance and Chloroplast Ultrastructure

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 744
Author(s):  
Petra Peharec Štefanić ◽  
Karla Košpić ◽  
Daniel Mark Lyons ◽  
Lara Jurković ◽  
Biljana Balen ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Cetyltrimethylammonium Bromide ◽  
Photosynthetic Apparatus ◽  
Chloroplast Ultrastructure ◽  
Photosynthetic Performance ◽  
Pigment Content ◽  
Inhibitory Effects ◽  
Tobacco Plants ◽  
Agriculture And Food ◽  
The Impact

Silver nanoparticles (AgNPs) are the most exploited nanomaterial in agriculture and food production, and their release into the environment raises concern about their impact on plants. Since AgNPs are prone to biotransformation, various surface coatings are used to enhance their stability, which may modulate AgNP-imposed toxic effects. In this study, the impact of AgNPs stabilized with different coatings (citrate, polyvinylpyrrolidone (PVP), and cetyltrimethylammonium bromide (CTAB)) and AgNO3 on photosynthesis of tobacco plants as well as AgNP stability in exposure medium have been investigated. Obtained results revealed that AgNP-citrate induced the least effects on chlorophyll a fluorescence parameters and pigment content, which could be ascribed to their fast agglomeration in the exposure medium and consequently weak uptake. The impact of AgNP-PVP and AgNP-CTAB was more severe, inducing a deterioration of photosynthetic activity along with reduced pigment content and alterations in chloroplast ultrastructure, which could be correlated to their higher stability, elevated Ag accumulation, and surface charge. In conclusion, intrinsic properties of AgNP coatings affect their stability and bioavailability in the biological medium, thereby indirectly contributing changes in the photosynthetic apparatus. Moreover, AgNP treatments exhibited more severe inhibitory effects compared to AgNO3, which indicates that the impact on photosynthesis is dependent on the form of Ag.

scholarly journals Verjüngungspotenzial verschiedener Waldföhrenund Fichtenherkünfte bei variabler Trockenheit

2015 ◽  
Vol 166 (6) ◽  
pp. 399-407 ◽  
Author(s):  
Barbara Moser ◽  
Marek Metslaid ◽  
Lorenz Walthert ◽  
Ulrich Wasem ◽  
Thomas Wohlgemuth
Keyword(s):  
Water Balance ◽  
Norway Spruce ◽  
Scots Pine ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Water Retention Capacity ◽  
Summer Drought ◽  
Retention Capacity ◽  
Rhine Valley ◽  
A Minor

Regeneration potential of different Scots pine and Norway spruce provenances under variable drought Rising temperatures will lead to extended periods of summer drought, which may challenge the persistence of Scots pine and Norway spruce in dry alpine valleys where these species play an important role in the protection against natural hazards. We tested whether the natural regeneration of the two species in the Rhine valley near Chur, Switzerland, might be limited under future climatic conditions and we compared the performance of autochthonous provenances with that of seedlings originating from regions with already drier summer climate such as the Rhone valley, continental Eastern Europe or the Mediterranean basin. Seeds of Scots pine and Norway spruce were sown repeatedly in forest clearings at three south-exposed sites in the Rhine valley near Chur, Switzerland. Soil moisture was manipulated to a minor extent with throughfall reduction roofs. In both species, regeneration success was primarily driven by the weather conditions during the three months following seed sowing: the seedlings having emerged in the rainy spring of 2013 had a higher survival rate and accumulated up to five times more aboveground biomass than the seedlings emerging in the dry spring of 2011. In years with an average or even positive water balance, Scots pine seedlings were able to establish at all sites. In Norway spruce, by contrast, establishment rate exceeded 10% of viable seeds only at the site with the highest water retention capacity. In years with a positive water balance during spring, the seedlings from the Rhine and Rhone valleys outperformed those from most Mediterranean and Eastern European provenances, while no differences between provenances were found in the dry spring of 2011. We suggest that periodical regeneration of Scots pine will be likely in the Rhine valley even under future climatic conditions, whereas the establishment of Norway spruce may remain an exceptional event in dry, south-exposed clearings.

scholarly journals INFLUENCE OF LIGHT AND HEAVY LANTHANIDES ON THE PHYSIOLOGICAL PROCESSES OF Taraxacum hybernum

2020 ◽  
Vol 8 (Spl-2-AABAS) ◽  
pp. S298-S302
Author(s):  
Vladimir Nikolaevich Vorob’ev ◽  
◽  
Sergei Fedorovich Kotov ◽  
Vera Vladimirovna Nikolenko ◽  
Denis Vladimirovich Tishin ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Photosynthetic Apparatus ◽  
Reaction Centers ◽  
Efficiency Change ◽  
Ps Ii ◽  
Antenna Complex ◽  
Physiological Processes ◽  
Light Lanthanide ◽  
Heavy Lanthanides ◽  
High Concentrations

The current study was carried out to study the influence of light and heavy lanthanides on the physiological process of Crimean-Sagyz/ Krim-saghyz (dandelion - Taraxacum hybernum). Lanthanide belongs to the group of light or heavy; infiltration of dandelion (Crimean saghyz) seeds with light and heavy lanthanides solutions increased the germination energy by 26%. The differences in the influence of light (cerium) and heavy (lutetium) were manifested in the quantum efficiency change of the photosystem 2 (PS II). Treatment of leaves with high concentrations (100 µM) led to a decrease of Y (II), moreover, under the influence of light lanthanide, the decrease was greater by 21%. It is assumed that the effect of the used lanthanides on the dandelion photosynthetic apparatus is multidirectional. Cerium influenced the PS II antenna complex, and lutetium influenced the reaction centers. A 10-fold decrease in the concentration did not change the nature of cerium action, except that Y (II) was restored already on the second day after treatment. The effect of lutetium became noticeable only by the 8th day after treatment when Y (II) became higher than that of untreated plants. Thus, the results of the study suggested that in dandelion leaves, lanthanides with a concentration of 10 µM increased the quantum efficiency of PS II in contrast to cerium.

Spatial and temporal variation in respiration in a young ponderosa pine forest during a summer drought

2001 ◽  
Vol 110 (1) ◽  
pp. 27-43 ◽  
Author(s):  
B.E Law ◽  
F.M Kelliher ◽  
D.D Baldocchi ◽  
P.M Anthoni ◽  
J Irvine ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Ponderosa Pine ◽  
Pine Forest ◽  
Spatial And Temporal Variation ◽  
Summer Drought ◽  
Ponderosa Pine Forest

Temporal variation in soil acidity

Soil Research ◽  
1997 ◽  
Vol 35 (5) ◽  
pp. 1115 ◽  
Author(s):  
M. K. Conyers ◽  
N. C. Uren ◽  
K. R. Helyar ◽  
G. J. Poile ◽  
B. R. Cullis
Keyword(s):  
Temporal Variation ◽  
Soil Ph ◽  
Soil Acidity ◽  
Soil Depth ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Variable Response ◽  
Related Factors ◽  
Exchangeable Al ◽  
Eastern Australia

Seasonal variation in the response of crops and pastures to limestone application has been observed on acidic soils in south-eastern Australia. Our hypothesis was that temporal variation in soil acidity related factors may contribute to this variable response. Soils from 4 annual pasture sites were sampled at least monthly for 3 years during 1988–1990 to monitor changes in pH(CaCl2) and in concentrations of exchangeable aluminium (Al) and manganese (Mn). The sites received no fertiliser or cultivation and therefore allowed for the estimation of natural temporal variation. Temporal variation in soil pH during a year ranged from 0 to 0·45 pH units depending on the site, soil depth, and the weather conditions. The larger changes in soil pH were associated with more extreme climatic conditions than normal, e.g. following the break of season after a hot, dry summer (autumn 1988) or during periods of above-average rainfall in autumn and early spring (1990). Temporal variation in pH was less than the spatial variability at the sites but greater than the long-term net acidification rate reported for the region. Temporal variation in the concentration of exchangeable Al ranged from 0 to 0·4 cmol(+)/kg during a year and varied primarily with the inverse of pH. Variations in the concentration of exchangeable Mn ranged from 0·05 to 0·35 cmol(+)/kg during a year. The concentration of exchangeable Mn increased over summer to an extent dependent on the drying of the soil. At the 2 sites with duplex profiles, maxima in the concentration of exchangeable Mn also occurred in spring, particularly in the warm wet spring of 1990. Soil tests for soil acidity therefore represent guides to probable risks of toxicity, as pH and the concentrations of exchangeable Al and Mn may change between soil sampling, sowing, and the period of crop or annual pasture growth. Such variations will alter the responsiveness of crops and pastures to lime.

scholarly journals Saharan Hot and Dry Sirocco Winds Drive Extreme Fire Events in Mediterranean Tunisia (North Africa)

Atmosphere ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 590 ◽  
Author(s):  
Chiraz Belhadj-Khedher ◽  
Taoufik El-Melki ◽  
Florent Mouillot
Keyword(s):  
Mediterranean Basin ◽  
Heat Waves ◽  
Fire Hazard ◽  
Weather Conditions ◽  
Burned Area ◽  
Summer Drought ◽  
Climate Conditions ◽  
The Mediterranean ◽  
The Mediterranean Basin ◽  
Extreme Fire

With hot and dry summers, the Mediterranean basin is affected by recurrent fires. While drought is the major driver of the seasonal and inter-annual fire distribution in its northern and mildest climate conditions, some extreme fire events are also linked to extreme winds or heat waves. The southern part of the Mediterranean basin is located at the driest range of the Mediterranean bioclimate and is influenced by Saharan atmospheric circulations, leading to extreme hot and dry episodes, called Sirocco, and potentially acting as a major contributor to fire hazard. The recently created fire database for Tunisia was used to investigate the ±10-day pre- and post-fire timeframe of daily weather conditions associated with fire events over the 1985–2006 period. Positive anomalies in minimum and maximum temperatures, negative anomalies in air relative humidity, and a preferential south-eastern wind during fire events were identified, which were characteristic of Sirocco winds. +7 °C anomalies in air temperature and −30% in relative air humidity were the critical thresholds for the most extreme fire conditions. In addition, meteorological anomalies started two days before fire events and lasted for three days after for large fires >400 ha, which suggests that the duration of the Sirocco event is linked with fire duration and final fire size. Lastly, the yearly number of intense Sirocco events better explained the inter-annual variability of burned area over the 1950–2006 period than summer drought based on Standardized Precipitation Evaporation Index (SPEI) indices.

Stress tolerance responses of two cotton cultivars exposed to ultraviolet-A (366 nm) radiation: photosynthetic performance and chemical constituents

2004 ◽  
Vol 52 (2) ◽  
pp. 113-124 ◽  
Author(s):  
M. K. H. Ebrahim
Keyword(s):  
Seed Germination ◽  
Stress Tolerance ◽  
Chemical Constituents ◽  
Photosynthetic Apparatus ◽  
Dry Mass ◽  
Inhibitory Effect ◽  
Photosynthetic Performance ◽  
Soluble Proteins ◽  
Hill Reaction ◽  
Ultraviolet A

The stress tolerance responses of two Egyptian cotton cultivars (Giza 45 and 86) exposed to various doses (40, 80, 160 and 320 min) of artificial ultraviolet-A (366 nm) radiation were investigated. The seed germination of Giza 86 was promoted at 40 min, but substantially inhibited at 80 and 160 min and completely suppressed at 320 min. However, the seed germination of Giza 45 was progressively inhibited by UV-A exposure and ceased at 160 min, so doses of 40 and 80 min were selected for further studies. In contrast to seed germination, the seedling growth of Giza 86 was negatively affected at 40 min. UV-A stress induced a great reduction in the leaf carbohydrates as well as in the viability and dry mass production of the shoots of both cultivars, but the response was comparatively higher in Giza 45. It also decreased the chorophyll (Chl) and carotenoid contents, coupled with an increase in the Chl a/b ratio, diminished the Hill reaction activity, and quenched the Chl a fluorescence both in the presence and absence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, suggesting an inhibitory effect on the water-splitting system (donor side) as well as on the electron transport from the primary to the secondary acceptors of PSII (acceptor side). These changes reflect a disturbance in the structure, composition and function of the photosynthetic apparatus as well as the sensitivity of PSII to UV-A stress. Nucleic acids (DNA and RNA) were markedly damaged by exposure to UV-A for 80 min, while both cultivars developed adaptive mechanisms for damage moderation. These mechanisms involved increasing the levels of flavonoids, total lipids and total soluble proteins as well as having smaller, thicker leaf blades. Since Giza 86 showed a comparatively higher level of adaptation, it tolerates UV-A stress better than Giza 45. Abbreviations: Car, carotenoids; Chl, chlorophyll; DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DCPIP, 2,6-dichlorophenol indophenol; DNA, deoxyribonucleic acid; d.m., dry mass; f.m., fresh mass; PSII, photosystem II; RNA, ribonucleic acid; TSP, total soluble proteins; UV-AR, ultraviolet-A (366 nm) radiation.

scholarly journals The Hawaiian Koʻa Card: coral health and bleaching assessment color reference card for Hawaiian corals

2020 ◽  
Vol 2 (10) ◽  
Author(s):  
Keisha D. Bahr ◽  
Sarah J. L. Severino ◽  
Anita O. Tsang ◽  
Justin J. Han ◽  
Angela Richards Dona ◽  
...  
Keyword(s):  
Coral Bleaching ◽  
Physiological State ◽  
Seawater Temperature ◽  
Photosynthetic Performance ◽  
Economic Life ◽  
Technical Solution ◽  
Community Members ◽  
Global Impacts ◽  
Wide Scale ◽  
Coral Health

Abstract Coral reefs are the foundation to our social, cultural, and economic life; however, reefs around the world are currently being threatened by many local and global impacts. Ongoing increases in seawater temperature pose significant threats to the integrity of these valuable ecosystems through extensive coral bleaching events. Therefore, we developed a coral health reference card, the Hawaiian Koʻa (coral) Card, to assess and quantify coral bleaching and to educate the community about its impacts in Hawai‘i. To accurately quantify the change in coral color during bleaching, controlled laboratory studies followed by field validations and surveys were conducted. Colors presented on the Hawaiian Koʻa Card have been linked to physiological state and health (e.g., symbiont density, chlorophyll levels, photosynthetic performance) of common coral species in Hawaiʻi due to bleaching. The Hawaiian Koʻa Card provides a technical solution to inform and improve management of our nearshore resources through collaborative monitoring efforts by community members, educators, researchers, and managers on a state-wide scale, which will assist in determining management efficacy, identifying regions and species of resilience, establishing baselines and focus areas, and developing and executing rapid response plans.

PHOTOSYNTHETIC CHARACTERIZATION OF A MUTANT OF NANNOCHLOROPSIS DEFICIENT IN THE SYNTHESIS OF EICOSAPENTAENOIC ACID

1998 ◽  
Vol 46 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Assaf Sukenik ◽  
Jane Schneider C. ◽  
Paul Roessler G. ◽  
Alexander Livne ◽  
Tamar Berner ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Eicosapentaenoic Acid ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Performance ◽  
Minor Role ◽  
Wild Type ◽  
Higher Temperature ◽  
A Minor

Photosynthetic performance of an eicosapentaenoic acid (EPA; 20:5ω3) deficient mutant of the eustigmatophyte Nannochloropsis sp. was compared to the wild type (Wt) strain in order to evaluate the effect of fatty acid composition on the function of the photosynthetic apparatus. Cellular photosynthetic capacity and the cellular pool of pigments and of reaction centers were reduced in the mutant concomitant with a reduction in the amount of thylakoid membranes and their volume-specific density. Despite the changes observed in photosynthetic activity, the fluorescence properties of the mutant were virtually the same as those of the wild type, although the phase transition of thylakoid membrane was recorded at higher temperature in the mutant than in the Wt. The results suggest that the change in one double bond in a very long chain fatty acid of the thylakoid lipids plays a minor role in regulating photosynthetic electron transport, but that the mutation modified the ability of the mutant to acclimate to low-irradiance conditions.

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