Seasonal changes in photosynthetic rate and pigment content in two populations of the monotypic Balkan serpentine endemic Halacsya sendtneri

2015 ◽  
Vol 63 (2) ◽  
pp. 167 ◽  
Author(s):  
Dražen D. Vicić ◽  
Milovan M. Stoiljković ◽  
Marko S. Sabovljević ◽  
Branka M. Stevanović
Keyword(s):  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Balkan Peninsula ◽  
Summer Period ◽  
Spring Period ◽  
Leaf Chlorophyll ◽  
Steep Decline ◽  
Microclimate Conditions ◽  
Two Populations

Halacsya sendtneri (Boiss.) Dörfl. is an obligate serpentine palaeoendemic of the Balkan Peninsula. It is able to maintain a favourable magnesium : calcium (Mg : Ca) ratio throughout its root and shoot, and grow in serpentine habitats with different microclimate conditions. Seasonal variation of leaf chlorophyll and carotenoid contents showed a steep decline right after the spring period, which was most probably caused by the drought imposed on the plants on the shallow serpentine soil. However, the in situ photosynthetic rate remained stable throughout the spring and summer period. Prolonged photosynthetic activity enables this species an investment into root development and sustainable survival in the harsh soils of the habitats it occupies.

Échanges gazeux de la tomate de serre cultivée sous éclairage d’appoint

1993 ◽  
Vol 73 (2) ◽  
pp. 577-585 ◽  
Author(s):  
Martine Dorais ◽  
Josée Charbonneau ◽  
André Gosselin
Keyword(s):  
Regression Analysis ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Photosynthetic Activity ◽  
Photon Flux ◽  
Tomato Seedlings ◽  
Échanges Gazeux ◽  
Supplemental Lighting ◽  
High Level

This study reports on in situ gas-exchange measurements in tomatoes grown under a sequential intercropping system with supplemental lighting provided by high-pressure sodium-vapour lamps. A supplemental photosynthetic photon flux (PPF) of 150 μmol m−2 s−1 significantly increased the amount of light energy penetrating the canopy of intercropped tomato seedlings. During the day, the supplemental 150 μmol m−2 s−1 light regime increased the photosynthetic rate of leaves 5 and 10 by 67%, while at night the increases were 93 and 12%, respectively. Regression analysis of the photosynthetic rate of leaves 5 and 10 as a function of PPF received accounts for 58 and 45% of the variation, respectively. Hierarchical analysis demonstrated a significant linear relationship between PPF received during the day and photosynthetic activity of leaves 5 and 10 accounting for 46 and 28%, respectively, of the variance in the model. Regression analysis of the photosynthetic activity as a function of PPF received at night accounts for 41 and 32%, respectively, of the variation in the photosynthetic rate of leaves 5 and 10. Using a high level of supplemental lighting during the day or at night had no significant effect on stomatic conductance or on the transpiration rate of leaves. Key words: Stomatal conductance, photosynthetic photo flux, Lycopersicon esculentum, photosynthesis, transpiration rate

Continuous in Situ Recording of the Photosynthetic Activity of Antarctic Lichens—established Methods and a New Approach

1991 ◽  
Vol 23 (3) ◽  
pp. 253-265 ◽  
Author(s):  
B. Schroeter ◽  
L. Kappen ◽  
C. Moldaenke
Keyword(s):  
Water Content ◽  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Dark Respiration ◽  
South Shetland Islands ◽  
Fibre Optics ◽  
Fluorescence Response ◽  
Gravimetric Water Content ◽  
Thallus Water Content

AbstractA new method is described that records the periods of photosynthetic and respiratory activity in lichen thalli in situ by measuring the actinic chlorophyll fluorescence response of the photobiont. The technique is based on a pulse amplitude modulation fluorometer that was specially developed for continuous and unattended measurements in the Antarctic. In Livingston Island, South Shetland Islands, the periods of metabolic activity of Usnea antarctica were recorded simultaneously with the microclimatic parameter in its natural environment. In one series of diurnal measurements the fluorescence response signal was treated as a qualitative on/off signal for photosynthetic activity. In a parallel series the diurnal courses of net photosynthesis and dark respiration of rain-moistened thalli of U. antarctica were measured by means of a CO2/H2O porometer together with gravimetric water content determination. Both methods showed marked coincidence from low water content to water saturation of the thalli. In the laboratory both the actinic fluorescence response and the photosynthetic rate as a function of thallus water content were investigated in Caloplaca regalis. In the laboratory experiments the CO2 exchange cuvette contained a balance for gravimetric water content control as well as the glass-fibre optics of the fluorescence analysis equipment. The experiments revealed a quantitative relationship between actinic fluorescence and photosynthetic rate within the range of optimum to limiting low thallus water content. The method described is suitable for measurements of lichen activity in field microclimate studies and should allow continuous unattended year-round measurements of lichen activity, which are needed in remote regions such as Antarctica.

scholarly journals Daily Variations of Photosynthetic Efficiency of Greenhouse Tomato Plants during Winter and Spring

2000 ◽  
Vol 125 (2) ◽  
pp. 235-241 ◽  
Author(s):  
O. Ayari ◽  
M. Dorais ◽  
A. Gosselin
Keyword(s):  
Photosynthetic Efficiency ◽  
Photosynthetic Activity ◽  
Photon Flux ◽  
Tomato Plants ◽  
Greenhouse Tomato ◽  
Northern Latitudes ◽  
Protective Strategy ◽  
Growing Conditions ◽  
Source Limitation

Daily and seasonal variations of photosynthetic activity, chlorophyll a (Chl-a) fluorescence and foliar carbohydrate content were studied in situ on greenhouse tomato (Lycopersicon esculentum Mill. `Trust') plants grown under CO2 enrichment and supplemental lighting. The objective of this study was to assess the effect of seasonal variation of the photosynthetic photon flux (PPF) on photosynthetic efficiency of tomato plants and to determine the presence or absence of photosynthetic down-regulation under greenhouse growing conditions prevailing in northern latitudes. During winter, the fifth and the tenth leaves of tomato plants showed low, constant daily photosynthetic activity suggesting a source limitation under low PPF. In winter, the ratio of variable to maximum Chl-a fluorescence in dark adapted state (Fv/Fm) remained constant during the day indicating no photoinhibition occurred. In February, an increase in photosynthetic activity was followed by a decline during March, April, and May accompanied by an increase in sucrose and daily starch concentrations and constant but high hexose level. This accumulation was a long-term response to high PPF and CO2 enrichment which would be caused by a sink limitation. Thus, in spring we observed an in situ downregulation of photosynthesis. The ratio Fv/Fm decreased in spring compared to winter in response to increasing PPF. The daily decline of Fv/Fm was observed particularly as a midday depression followed by a recovery towards the end of the day. This indicated that tomato leaves were subject to a reversible inhibition in spring. Fv/Fm was lower in March than in April and May even though PPF was higher in April and May than in March. These results suggest that tomato plants develop an adaptive and protective strategy as PPF increases in spring.

scholarly journals Leaf and community photosynthetic carbon assimilation of alpine plants under in-situ warming

2020 ◽  
Author(s):  
Zhou Zijuan ◽  
Su Peixi ◽  
Wu Xiukun ◽  
Shi Rui ◽  
Ding Xinjing
Keyword(s):  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Climate Warming ◽  
Alpine Meadow ◽  
Carbon Assimilation ◽  
Community Level ◽  
Photosynthetic Carbon ◽  
Leaf Level ◽  
Photosynthetic Carbon Assimilation

Abstract Background: The Tibetan Plateau is highly sensitive to elevated temperatures and has experienced significant climate warming in the last decades. While climate warming is known to greatly impact alpine ecosystems, the gas exchange responses at the leaf and community levels to climate warming in alpine meadow ecosystems remain unclear.Results: In this study, the alpine grass, Elymus nutans, and forb, Potentilla anserina, were grown in open-top chambers (OTCs) for three consecutive years to evaluate their response to warming. Gas exchange measurements were used to assess the effects of in-situ warming on leaf- and community-level photosynthetic carbon assimilation based on leaf traits and photosynthetic physiological parameters. We introduced a means of up-scaling photosynthetic measurements from the leaf level to the community level based on six easily-measurable parameters, including leaf net photosynthetic rate, fresh leaf mass per unit leaf area, fresh weight of all plant leaves, the percentage of healthy leaves, the percentage of received effective light by leaves in the community, and community coverage. The community-level photosynthetic carbon assimilation and productivity all increased with warming, and the net photosynthetic rate at the leaf level was significantly higher than at the community level. Under elevated temperature, the net photosynthetic rate of E. nutans decreased, while that of P. anserina increased.Conclusions: These results indicated that climate warming may significantly influence plant carbon assimilation, which could alter alpine meadow community composition in the future.

scholarly journals Acclimation of Photosynthetic Activity of Zantedeschia `Best Gold' in Response to Temperature and Photosynthetic Photon Flux

2002 ◽  
Vol 127 (2) ◽  
pp. 290-296 ◽  
Author(s):  
Keith A. Funnell ◽  
Errol W. Hewett ◽  
Julie A. Plummer ◽  
Ian J. Warrington
Keyword(s):  
Quantum Yield ◽  
Leaf Area ◽  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Natural Habitat ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Leaf Area Expansion ◽  
Response To Temperature ◽  
Area Expansion

Photosynthetic activity of individual leaves of Zantedeschia Spreng. `Best Gold' aff. Z. pentlandii (Wats.) Wittm. [syn. Richardia pentlandii Wats.] (`Best Gold'), were quantified with leaf expansion and diurnally, under a range of temperature and photosynthetic photon flux (PPF) regimes. Predictive models incorporating PPF, day temperature, and percentage leaf area expansion accounted for 78% and 81% of variation in net photosynthetic rate (Pn) before, and postattainment of, 75% maximum leaf area, respectively. Minimal changes in Pn occurred during the photoperiod when environmental conditions were stable. Maximum Pn (10.9μmol·m-2·s-1 or 13.3 μmol·g-1·s-1) occurred for plants grown under high PPF (694 μmol·m-2·s-1) and day temperature (28 °C). Acclimation of Pn was less than complete, with any gain through a greater light-saturated photosynthetic rate (Pmax) at high PPF also resulting in a reduction in quantum yield. Similarly, any gain in acclimation through increased quantum yield under low PPF occurred concurrently with reduced Pmax. It was concluded that Zantedeschia `Best Gold' is a shade tolerant selection, adapted to optimize photosynthetic rate under the climate of its natural habitat, by not having obligate adaptation to sun or shade habitats.

scholarly journals Structure and ecological peculiarities of algoflora of rock-forming soils of coal dumps in Donetsk region

2013 ◽  
pp. 379-387
Author(s):  
Mykola Chajka ◽  
Iryna Mal’tseva
Keyword(s):  
Key Words ◽  
Coal Mining ◽  
Soil Algae ◽  
Summer Period ◽  
Spring Period

As a result of the investigation of algogroups of coal-mining workings of mine administration “Zahidne” 44 species of algal from five departments (Cyanophyta, Chlorophyta, Bacillariophyta, Xanthophyta, Eustigmatophyta) were revealed. The coefficients of mesophility and xerophylity are calculated. The general spectrum of vital forms of algae species in spring period is represented by formula Ch14B5X3H2C2P1 (27), in summer period – Ch9P8B7X4H4C2V1CF1 (36). Key words: coal dump, soil algae, vital forms.

scholarly journals Comparative analysis of populations of the Balkan endemic species Daphne malyana Blecic (Thymeleaceae)

2010 ◽  
Vol 62 (4) ◽  
pp. 1151-1162 ◽  
Author(s):  
Marina Juskovic ◽  
P. Vasiljevic ◽  
V. Randjelovic ◽  
V. Stevanovic ◽  
Branka Stevanovic
Keyword(s):  
Principal Component Analysis ◽  
Comparative Analysis ◽  
Endemic Species ◽  
Morphological Variability ◽  
Principal Component ◽  
Balkan Peninsula ◽  
Canonical Discriminant Analysis ◽  
The Other ◽  
Isolated Populations ◽  
Microclimate Conditions

Daphne malyana Blecic (Thymeleaceae) is an endemic species of the western part of the Balkan Peninsula, distributed in the mountains, canyons and gorges of N. Montenegro, E. Bosnia and W. Serbia. The comparative morphoanatomic investigations have included four distantly separated populations of the species D. malyana, i.e. two from Serbia, from the ravines of Sokoline and Vranjak on Mt. Tara, and two from Montenegro, in the canyons of the Tara and Piva rivers. Comparative morphoanatomical studies have shown the presence of general adaptive characteristics of a specific, conservative xeromorphic type, slightly differing in each population. Principal component analysis (PCA) and canonical discriminant analysis (CDA) of 20 morphoanatomical characteristics of the leaves and stems have shown a clear distinction between the populations from the river Piva canyon (Montenegro) and those from the Sokoline ravine (Serbia), on one side, and those of Vranjak gorge (Serbia) and of the river Tara canyon (Montenegro) on the other side. It may be assumed that the mild morphological variability of the isolated populations of the Balkan endemic species D. malyana in the canyons and gorges seem to have been affected by the microclimate conditions in their habitats.

In Situ Study of The Exposure of Polycarbonate to an Argon Plasma

1995 ◽  
Vol 385 ◽  
Author(s):  
S. Vallon ◽  
B. Drevillon ◽  
F. Poncin-Epaillard ◽  
J. C. Rostaing
Keyword(s):  
Structural Changes ◽  
Argon Plasma ◽  
Silica Layer ◽  
Molecular Weights ◽  
In Situ Study ◽  
Polar Groups ◽  
Unit Scale ◽  
Two Populations ◽  
Polymer Unit

ABSTRACTThe exposure of polycarbonate to an argon plasma is studied using in situ ellipsometry from the UV to the IR, nuclear magnetic resonance and light scattering measurements. An increase in the refractive index and the existence of two populations of different molecular weights show that structural changes occur in the polymer. They are correlated with modifications at the polymer unit scale, such as formation of new polar groups and decrease in dimethyl groups. Two simultaneous reaction mechanisms must be considered to account for these changes. The adhesion of a silica layer on treated polycarbonate is then discussed.

scholarly journals Acid–base physiology over tidal periods in the mussel Mytilus edulis : size and temperature are more influential than seawater pH

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182863 ◽  
Author(s):  
Stephanie Mangan ◽  
Rod W. Wilson ◽  
Helen S. Findlay ◽  
Ceri Lewis
Keyword(s):  
Mytilus Edulis ◽  
Environmental Changes ◽  
Interactive Effect ◽  
Marine Biota ◽  
Acid Base ◽  
Tidal Cycles ◽  
Seawater Ph ◽  
Seawater Carbonate Chemistry ◽  
Two Populations

Ocean acidification (OA) studies to date have typically used stable open-ocean pH and CO 2 values to predict the physiological responses of intertidal species to future climate scenarios, with few studies accounting for natural fluctuations of abiotic conditions or the alternating periods of emersion and immersion routinely experienced during tidal cycles. Here, we determine seawater carbonate chemistry and the corresponding in situ haemolymph acid–base responses over real time for two populations of mussel ( Mytilus edulis ) during tidal cycles, demonstrating that intertidal mussels experience daily acidosis during emersion. Using these field data to parameterize experimental work we demonstrate that air temperature and mussel size strongly influence this acidosis, with larger mussels at higher temperatures experiencing greater acidosis. There was a small interactive effect of prior immersion in OA conditions (pH NBS 7.7/pCO 2 930 µatm) such that the haemolymph pH measured at the start of emersion was lower in large mussels exposed to OA. Critically, the acidosis induced in mussels during emersion in situ was greater (ΔpH approximately 0.8 units) than that induced by experimental OA (ΔpH approximately 0.1 units). Understanding how environmental fluctuations influence physiology under current scenarios is critical to our ability to predict the responses of key marine biota to future environmental changes.

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