scholarly journals Photosynthetic characteristics of a tropical population of Nitella cernua (Characeae, Chlorophyta)

2006 ◽  
Vol 18 (3) ◽  
pp. 379-388 ◽  
Author(s):  
Jair Vieira Jr. ◽  
Orlando Necchi Jr.
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Wide Distribution ◽  
Photosynthetic Performance ◽  
High Irradiance ◽  
Photosynthetic Characteristics ◽  
Southeastern Brazil ◽  
Photochemical Quenching ◽  
O2 Evolution ◽  
Photosynthetic Rates

Photosynthetic characteristics (assessed by chlorophyll fluorescence and O2 evolution) were analysed monthly during one year in a tropical population of Nitella cernua from southeastern Brazil (20º50'32" S, 49º26'15" W). Parameters derived from photosynthesis-irradiance (PI) curves by fluorescence (high values of the photosynthetic parameter, Ik, and lack or low values of photoinhibition, beta) suggested adaptation to high irradiance, whereas those by O2 evolution showed a different pattern (low values of Ik and compensation irradiance, Ic, high values of photosynthetic efficiency, alpha, and photoinhibition). Parameters from PI curves by O2 evolution suggested light acclimation: Ik and maximum photosynthetic rate, Pmax (as rETR, relative electron transfer rate) increased, whereas a became significantly lower under higher irradiance (winter). This pattern is an adjustment of both number and size of photosynthetic units. Photosynthetic performance assessed by fluorescence revealed two seasonal periods: higher values of Pmax (rETR), Ik and non-photochemical quenching from October to March (rainy season), and lower values from April to October (dry season). Temperature responses were observed only in summer, but temperature optima were different between methods: peaks of net photosynthesis occurred at 20ºC, whereas rETR increased towards higher temperatures (up to 30ºC). Dark respiration increased with higher temperatures. Current velocity had a stimulatory effect on photosynthetic rates, as suggested by positive correlations with Pmax (rETR) and alpha. pH experiments revealed highest net photosynthetic rates under pH 4.0, suggesting higher affinity for CO2 than HCO3-. This broad range of responses of photosynthetic characteristics of this N. cernua population to irradiance, temperature, and pH/inorganic carbon reflects a wide tolerance to variations in these environmental variables, which probably contribute to the wide distribution of this species.

The ecology of Ramalina menziesii. VI. Laboratory responses of net CO2 exchange to moisture, temperature, and light

1987 ◽  
Vol 65 (1) ◽  
pp. 182-191 ◽  
Author(s):  
U. Matthes-Sears ◽  
T. H. Nash III ◽  
D. W. Larson
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Response Curves ◽  
Central California ◽  
Photosynthetic Rates ◽  
Chlorophyll Contents ◽  
The Mean ◽  
The Difference ◽  
Thallus Water Content

The response of net CO2 exchange to thallus water content, thallus temperature, and photosynthetically active radiation was measured in the laboratory for two morphologically different forms of Ramalina menziesii collected from a coastal and an inland habitat in central California. Equations describing the response curves are fitted to the data and compared statistically for the two sites during two seasons. Significant differences were present for all responses both in summer and winter but were more pronounced for net photosynthesis than for dark respiration. The main differences between the two forms were in the absolute rates of net photosynthesis; a maximum of 6.2 was measured for the inland form but only 3.6 mg∙g−1∙h−1 for the coastal form. Chlorophyll contents were also different between the two forms, indicating that chlorophyll is the likely cause for the difference in net photosynthetic rates. Net photosynthetic rates were higher at low temperatures during winter than during summer, but otherwise seasonal variations in the gas exchange responses were relatively minor. Both forms of the lichen are light saturated at quantum fluxes greater than 200 μE∙m−2∙s−1. Both show an optimum temperature for maximum CO2 exchange at 25 °C, well above the mean operating temperature of R. menziesii in the field.

Physiological changes and UV protection in the aquatic liverwort Jungermannia exsertifolia subsp. cordifolia along an altitudinal gradient of UV-B radiation

2006 ◽  
Vol 33 (11) ◽  
pp. 1025 ◽  
Author(s):  
María Arróniz-Crespo ◽  
Encarnación Núñez-Olivera ◽  
Javier Martínez-Abaigar ◽  
Hans Becker ◽  
Jochen Scher ◽  
...  
Keyword(s):  
Altitudinal Gradient ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Secondary Compounds ◽  
Photochemical Quenching ◽  
Physiological Variables ◽  
Linear Relationships ◽  
Spatial Changes ◽  
Uv Absorbing Compounds ◽  
Non Photochemical Quenching

Here we report the effects of a natural altitudinal gradient of UV-B radiation, from 1140 to 1816 m altitude, on the physiology of the aquatic liverwort Jungermannia exsertifolia Steph. subsp. cordifolia (Dumort.) Váña collected in mountain streams. Photosynthetic pigments, net photosynthesis and dark respiration rates, chlorophyll fluorescence, protein concentration, sclerophylly, and UV-absorbing compounds [both global UV absorbance of methanol-extractable UV-absorbing compounds (MEUVAC) and concentrations of five individual compounds] were measured. Two new caffeic acid derivatives were discovered: 5″-(7″,8″-dihydroxycoumaroyl)-2-caffeoylmalic acid and 5″-(7″,8″-dihydroxy-7-O-β-glucosyl-coumaroyl)-2-caffeoylmalic acid, whereas three additional compounds were already known in other species: p-coumaroylmalic acid, phaselic acid (both compounds in their cis- and trans- forms) and feruloylmalic acid. Most physiological variables changed considerably along the altitudinal gradient, but only six showed significant linear relationships with altitude: MEUVAC levels, the concentrations of the two new secondary compounds, the maximal apparent electron transport rate through PSII (ETRmax) and the maximal non-photochemical quenching (NPQmax) increased with altitude, whereas photoinhibition percentage decreased. A principal components analysis (PCA) was conducted to rank the values of the physiological and ecological variables obtained along the altitudinal transect, showing that those variables correlated with altitude were responsible for the ordination of the sampling points. The liverwort was not adversely affected by the changing conditions along the altitudinal gradient and, in particular, by the increasing UV-B irradiance, probably because the characteristics shown by high-altitude populations may confer tolerance to high UV-B levels. The response to UV-B of the two new compounds suggests that they could be used as indicators of the spatial changes in UV-B radiation.

Effect of Nitrogen Content on the Photosynthetic Characteristics of Sunflower Leaves

1993 ◽  
Vol 20 (3) ◽  
pp. 251 ◽  
Author(s):  
DJ Connor ◽  
AJ Hall ◽  
VO Sadras
Keyword(s):  
Nitrogen Content ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Leaf Nitrogen ◽  
Mean Value ◽  
Life Cycles ◽  
High Irradiance ◽  
Response Curves ◽  
Unit Leaf ◽  
Wide Range

Photosynthesis-irradiance response curves and leaf nitrogen contents were measured weekly by destructive sampling over the life cycles of leaves 10, 15, 20 and 25 of sunflower plants (cv. Prosol 35) grown in large pots in the open under optimum conditions of temperature and high irradiance. Individual leaf responses were adequately described by a hyperbola of three parameters, viz. Pmax, the rate of photosynthesis in saturating irradiance; R, the rate of dark respiration adjusted for temperature (30�C); and ε, the apparent quantum efficiency of photosynthesis at low irradiance. Pmax (range 0-40 μmol CO2 m-2 s-1) and R (0-4 μmol CO2 m-2 s-1) were non-linearly related to nitrogen content per unit leaf area (NL) (range 0.3-2.9 g N m-2) across all leaf positions and for all leaf ages. ε (mean value 0.050 mol mol-1, s.e. 0.001) was independent of NL. The equations for net photosynthesis derived from pot studies were shown to explain (r2 =0.80) leaf photosynthesis in a crop of the same cultivar over a wide range of NL and irradiance.

C4Photosynthesis in Smooth Pigweed

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 127-130 ◽  
Author(s):  
David T. Patterson
Keyword(s):  
Net Photosynthetic Rate ◽  
Photosynthetic Rate ◽  
Net Photosynthesis ◽  
Gas Analysis ◽  
Photosynthetic Characteristics ◽  
Optimum Temperature ◽  
Amaranthus Hybridus ◽  
Photosynthetic Rates ◽  
Compensation Concentration ◽  
Smooth Pigweed

The response of net photosynthetic rate to temperature and light, the rate of photorespiration, the compensation concentration for CO2, and the pathway of CO2fixation in smooth pigweed (Amaranthus hybridusL.) were investigated using infrared gas analysis and14CO2. Maximum net photosynthetic rates of whole shoots were 45 mg CO2dm-2hr-1at 30 C and 7.8 klux. Intact whole shoots were not light saturated at 10 klux. The optimum temperature for net photosynthesis was between 30 C and 40 C. Photorespiration was low and the CO2compensation concentration was 7 ppm. After a 5-sec exposure to14CO2in the light, label was detected in oxaloacetate, malate, and aspartate. It was concluded that smooth pigweed has the gross photosynthetic characteristics and CO2fixation pathway typical of C4or Hatch-Slack plants.

Effect of irradiance on growth and photosynthesis of Populus × euramericana clones

1978 ◽  
Vol 8 (1) ◽  
pp. 94-99 ◽  
Author(s):  
F. E. Fasehun
Keyword(s):  
Growth Rate ◽  
Laboratory Experiments ◽  
Dark Respiration ◽  
High Irradiance ◽  
Dark Respiration Rate ◽  
Photosynthetic Rates ◽  
Populus Euramericana ◽  
Unit Leaf ◽  
Whole Plant ◽  
Plant Photosynthesis

Greenhouse and laboratory experiments were conducted to determine the effect of irradiance level on growth and photosynthesis of three Populus × euramericana clones selected to exhibit differences in growth rate when grown under full sunlight. Individual plants were started from apical cuttings and grown in the greenhouse for 13 weeks under three levels of shading (37%, 75%, and 100% full light). Rates of leaf and whole plant photosynthesis and dark respiration were measured with an infrared gas analyzer.Clone 5323 grew relatively well under all irradiance levels, and the older leaves of this clone had the highest photosynthetic rates per unit leaf area under the higher growth irradiances. Clone 5326, which had the least growth, also had the lowest per-plant photosynthesis rate under all irradiance levels. Clone 5321 had per-plant photosynthetic rates comparable with those of clone 5323 but a higher dark respiration rate when grown at the high irradiance levels.

Photosynthesis and dark respiration of black spruce cuttings during rooting in response to light and temperature

1993 ◽  
Vol 23 (6) ◽  
pp. 1150-1155 ◽  
Author(s):  
De Yue ◽  
Hank A. Margolis
Keyword(s):  
Black Spruce ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Experimental Period ◽  
Photon Flux ◽  
Photosynthetic Rates ◽  
Physiological Quality ◽  
Use Efficiency ◽  
Total Dry Weight

Photosynthesis and dark respiration of semihardened black spruce cuttings (Piceamariana (Mill.) B.S.P.) were periodically measured at a range of light intensities at 10, 15, 20, 25, and 30 °C over an 8-week period in rooting chambers and for 4 additional weeks after the cuttings were transferred to a greenhouse. Increases in the total dry weight of the cuttings over the experimental period were due exclusively to increases in root biomass. The light-saturated photosynthetic rates at 20 °C decreased from 3.8 to 2.2 μmol CO2•m−2•s−1 during the 8 weeks in the rooting chamber. At 15 °C, the light-saturated photosynthetic rate was about 2 μmol CO2•m−2•s−1 and no significant change was observed during the experimental period. Maximum photosynthetic rates were generally attained at photosynthetic photon flux densities (PPFD) of 200–300 μmol•m−2•s−1 At the range of PPFD generally used in rooting chambers (0–50 μmol•m−2•s−1), the light use efficiency of cuttings (net photosynthesis per cutting per PPFD) was greatest at 15 °C. Furthermore, the light compensation point was lowest at 15 °C. The effect of light intensity and temperature on the photosynthesis and dark respiration of cuttings was modelled to predict the carbon balance of cuttings under different conditions of PPFD and temperature. This model should be useful in determining an appropriate set of environmental conditions to use inside rooting chambers and thus improve the overall physiological quality of this type of vegetatively propagated planting stock. The modelling approach described in this study could prove useful for the production of other conifer species by rooted cuttings even when it is conducted using other methods of cultivation (e.g., cold-frames or greenhouses).

scholarly journals Photosynthetic Physiology Comparisons between No Tillage and Sod Culture of Citrus Farming in Different Seasons under Various Light Intensities

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1805
Author(s):  
Chung-I. Chen ◽  
Kuan-Hung Lin ◽  
Meng-Yuan Huang ◽  
Chih-Kai Yang ◽  
Yu-Hsiu Lin ◽  
...  
Keyword(s):  
Dark Respiration ◽  
Photosynthetic Apparatus ◽  
Net Photosynthesis ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Light Quantum ◽  
No Tillage ◽  
Photosynthetic Physiology ◽  
Light Intensities ◽  
Different Seasons

Sod culture (SC) and no tillage (NT) are modern orchard management systems, and are two different bases for the sustainable development and production of citrus orchards in Taiwan. However, there is no information about the efficiency of either NT or SC on the photosynthetic physiology of farmed citrus under different seasons and varying light intensities. The objective of this study was to clarify the impacts of SC and NT under eco-friendly farming management on the photosynthetic apparatus of an important plantation citrus species in response to varying light intensities over the seasons. The results showed that Rd (dark respiration rate of CO2), Qy (light quantum yield of CO2), LCP (light compensation point), Amax (maximum net assimilation of CO2), and Fv/Fm values of citrus plants under SC were somewhat higher under NT in the same season, particularly in the fall and in winter. As light intensity increased from 200 to 2000 μmol photon m−2 s−1 PPFD, higher Pn (net photosynthesis rate), Gs (stomatal conductance), ETR (electron transport rate), NPQ (non-photochemical quenching), and Fv/Fm (potential quantum efficiency of PSII) values were observed in spring and summer compared to the fall and winter, and increasing NPQ and decreasing Fv/Fm values were observed in all seasons. Positive and significant correlations were shown between the Pn and Gs under NT and SC in all seasons with all light illuminations, whereas significant and negative relationships were observed between the ETR and NPQ under NT in fall and winter at 1200~2000 PPFD. In short, ETR was useful for non-destructive estimations of Pn and NPQ since these indices were significantly and positively correlated with ETR in citrus leaves exposed to 0~1200 PPFD in all seasons and 1200~2000 PPFD in spring, the fall, and winter, providing a quick means to identify the physiological condition of plants under various seasons and tillages. The precise management of photosynthetic parameters such as ETR in response to light irradiances under varied seasons also provides implications for sustainable citrus production for tillage cropping systems in future higher CO2 and potentially wetter or drier environments. The tillages may hold promise for maximizing the economic efficiency of the growth and development of citrus plants grown in the field.

scholarly journals Evaluation of Heat and Flood Tolerance among Diverse Taxa of Hollies (Ilex)

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 600d-600
Author(s):  
Thomas G. Ranney ◽  
John M. Ruter ◽  
Clifford D. Ruth
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosynthetic Capacity ◽  
Root Zone ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Flood Tolerance ◽  
Sensitive Species ◽  
Photosynthetic Rates ◽  
Temperature Responses ◽  
Temperature Optima

Temperature sensitivity of net photosynthesis (PSN), dark respiration, and chlorophyll fluorescence was evaluated among three taxa of hollies including I. aquifolium, I. cornuta, and I. rugosa. Variations in foliar heat tolerance among these species were expressed as differential temperature responses for PSN. Temperature optima for PSN was 22.0, 26.3 and 27.9 umol·m–2·s–1 for I. rugosa, I. cornuta, and I. aquifolium, respectively. Differences in temperature optima for PSN and thermotolerance of PSN appeared to result from a combination of stomatal and nonstomatal limitations. At 40°C, potential photosynthetic capacity, measured under saturating CO2, was 4.1, 9.4, and 14.8 μmol·m–2·s–1 for I. rugosa, I. aquifolium, and I. cornuta, respectively. Based on these results, I. rugosa was identified as the most heat-sensitive species followed by I. aquifolium then I. cornuta. Comparative tolerance to root-zone inundation was evaluated among 14 holly taxa. Following 8 weeks of flooding, four of the taxa: I. cornuta `Burfordii', I. × `Nellie R. Stevens', I. cassine, and I. × attenuata `Foster's #2' performed remarkably well during and after flooding with photosynthetic rates > 40% of the controls, root ratings >75% of the controls, <5% of the foliage showing deterioration, and 100% survival. Conversely, I. crenata `Convexa', Ilex × meserveae `Blue Princess', I. rugosa and I. aquifolium `Sparkler' did not tolerate flooding well as indicated by severely depressed photosynthetic rates, deterioration of foliage and roots, and decreased survival. The remaining taxa were intermediate.0

scholarly journals Physiological performance of Persian acroporid corals in summer versus winter temperatures

2014 ◽  
Author(s):  
Jahangir Vajed Samiei ◽  
Abolfazl Saleh ◽  
Ali Mehdinia ◽  
Arash Shirvani ◽  
Mohsen Kayal
Keyword(s):  
Persian Gulf ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Photosynthetic Performance ◽  
Maximum Temperature ◽  
Extreme Temperatures ◽  
Physiological Performance ◽  
Coral Health ◽  
Temperature Levels ◽  
The Persian Gulf

With ongoing climate change, coral susceptibility to thermal stress constitutes a central concern in reef conservation. In the Persian Gulf, coral reefs are confronted with the most extreme temperatures. Over the last decades, both annual hot and cold peak periods in this region have been associated with episodes of coral bleaching and mortality. Using physiological performance as a measure of coral health, we investigated the thermal susceptibility of the common acroporid coral from the Persian Gulf, Acropora downingi, in Hengam Island where temperature oscillates seasonally in the range 20.2-34.2°C. In a series of two short-term experiments, we exposed corals (1) to the constant temperature levels of summer versus winter, and (2) to progressive temperature deviations from the annual mean toward the two extreme seasonal values and beyond. We monitored four indictors of coral physiological performance: net photosynthesis (Pn), dark respiration (R), autotrophic capability (Pn/R), and survival. Warming revealed detrimental for Pn and survival of corals, while equivalent cooling did not. Pn/R was lower at the warmer thermal level within each season, and during summer compared to winter. Corals exposed to the maximum temperature of summer displayed Pn/R<1, inferring that photosynthetic performance could not support basal metabolic needs under this environment and that corals had to import organic matter or draw on their reserves to compensate for carbon losses during respiration. We therefore suggest that the Persian Gulf populations of A. downingi are more sensitive to the extreme temperatures endured in summer compared to that experienced in winter; and they may be impacted by future increases in water temperature.

scholarly journals Physiological performance of Persian acroporid corals in summer versus winter temperatures

2014 ◽  
Author(s):  
Jahangir Vajed Samiei ◽  
Abolfazl Saleh ◽  
Ali Mehdinia ◽  
Arash Shirvani ◽  
Mohsen Kayal
Keyword(s):  
Persian Gulf ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Photosynthetic Performance ◽  
Maximum Temperature ◽  
Extreme Temperatures ◽  
Physiological Performance ◽  
Coral Health ◽  
Temperature Levels ◽  
The Persian Gulf

With ongoing climate change, coral susceptibility to thermal stress constitutes a central concern in reef conservation. In the Persian Gulf, coral reefs are confronted with the most extreme temperatures. Over the last decades, both annual hot and cold peak periods in this region have been associated with episodes of coral bleaching and mortality. Using physiological performance as a measure of coral health, we investigated the thermal susceptibility of the common acroporid coral from the Persian Gulf, Acropora downingi, in Hengam Island where temperature oscillates seasonally in the range 20.2-34.2°C. In a series of two short-term experiments, we exposed corals (1) to the constant temperature levels of summer versus winter, and (2) to progressive temperature deviations from the annual mean toward the two extreme seasonal values and beyond. We monitored four indictors of coral physiological performance: net photosynthesis (Pn), dark respiration (R), autotrophic capability (Pn/R), and survival. Warming revealed detrimental for Pn and survival of corals, while equivalent cooling did not. Pn/R was lower at the warmer thermal level within each season, and during summer compared to winter. Corals exposed to the maximum temperature of summer displayed Pn/R<1, inferring that photosynthetic performance could not support basal metabolic needs under this environment and that corals had to import organic matter or draw on their reserves to compensate for carbon losses during respiration. We therefore suggest that the Persian Gulf populations of A. downingi are more sensitive to the extreme temperatures endured in summer compared to that experienced in winter; and they may be impacted by future increases in water temperature.

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