scholarly journals Photosynthetic responses of three common mosses from continental Antarctica

2005 ◽  
Vol 17 (3) ◽  
pp. 341-352 ◽  
Author(s):  
STEFAN PANNEWITZ ◽  
T.G. ALLAN GREEN ◽  
KADMIEL MAYSEK ◽  
MARK SCHLENSOG ◽  
ROD SEPPELT ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Content ◽  
Dark Respiration ◽  
Temperature Response ◽  
Environmental Parameters ◽  
Net Photosynthesis ◽  
Photon Flux ◽  
Terrestrial Vegetation ◽  
Moss Species ◽  
Victoria Land

Predicting the effects of climate change on Antarctic terrestrial vegetation requires a better knowledge of the ecophysiology of common moss species. In this paper we provide a comprehensive matrix for photosynthesis and major environmental parameters for three dominant Antarctic moss species (Bryum subrotundifolium, B. pseudotriquetrum and Ceratodon purpureus). Using locations in southern Victoria Land, (Granite Harbour, 77°S) and northern Victoria Land (Cape Hallett, 72°S) we determined the responses of net photosynthesis and dark respiration to thallus water content, thallus temperature, photosynthetic photon flux densities and CO2 concentration over several summer seasons. The studies also included microclimate recordings at all sites where the research was carried out in field laboratories. Plant temperature was influenced predominantly by the water regime at the site with dry mosses being warmer. Optimal temperatures for net photosynthesis were 13.7°C, 12.0°C and 6.6°C for B. subrotundifolium, B. pseudotriquetrum and C. purpureus, respectively and fall within the known range for Antarctic mosses. Maximal net photosynthesis at 10°C ranked as B. subrotundifolium > B. pseudotriquetrum > C. purpureus. Net photosynthesis was strongly depressed at subzero temperatures but was substantial at 0°C. Net photosynthesis of the mosses was not saturated by light at optimal water content and thallus temperature. Response of net photosynthesis to increase in water content was as expected for mosses although B. subrotundifolium showed a large depression (60%) at the highest hydrations. Net photosynthesis of both B. subrotundifolium and B. pseudotriquetrum showed a large response to increase in CO2 concentration and this rose with increase in temperature; saturation was not reached for B. pseudotriquetrum at 20°C. There was a high level of variability for species at the same sites in different years and between different locations. This was substantial enough to make prediction of the effects of climate change very difficult at the moment.

Genotypic Variation in Light and Temperature Response of Photosynthesis in Nothofagus solandri Var. cliffortioides and N. menziesii

1996 ◽  
Vol 23 (4) ◽  
pp. 421 ◽  
Author(s):  
OJ Sun ◽  
GB Sweet
Keyword(s):  
New Zealand ◽  
Dark Respiration ◽  
Genotypic Variation ◽  
Temperature Response ◽  
Light Response ◽  
Net Photosynthesis ◽  
Photosynthetic Photon Flux Density ◽  
Ecosystem Dynamics ◽  
Photon Flux ◽  
Photon Flux Density

Responses of photosynthesis to light and temperature were studied in two Nothofagus species native to New Zealand: N. solandri var. cliffortioides (Hook. f.) Poole and N. menziesii (Hook. f.) Oerst.. Measurements of leaf photosynthesis were made in a controlled environment growth chamber at photosynthetic photon flux density between 0 and 700 μmol m-2 s-1 with temperatures set for 10, 20 and 25�C, on seedlings previously grown in a glasshouse from seed of three different origins. In both species, pronounced intraspecific variation was shown in dark respiration, light compensation point and light-saturated net photosynthesis (Amax). Seedlings of N. solandri showed higher dark respiration and light compensation levels than N. menziesii seedlings, but the two species did not differ in Amax. Change in temperature resulted in significant change in the response of photosynthesis to light in both N. solandri and N. menziesii. The differences between N. solandri and N. menziesii in light response of photosynthesis are discussed in terms of ecosystem dynamics of Nothofagus forests in New Zealand.

Photosynthetic light and temperature responses of Eucalyptus cloeziana and Eucalyptus argophloia

2003 ◽  
Vol 51 (5) ◽  
pp. 573 ◽  
Author(s):  
Michael R. Ngugi ◽  
Mark A. Hunt ◽  
David Doley ◽  
Paul Ryan ◽  
Peter J. Dart
Keyword(s):  
Quantum Yield ◽  
Dark Respiration ◽  
Temperature Response ◽  
Net Photosynthesis ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Response Curves ◽  
Growth Environment ◽  
Eucalyptus Cloeziana

Acclimation of gas exchange to temperature and light was determined in 18-month-old plants of humid coastal (Gympie) and dry inland (Hungry Hills) provenances of Eucalyptus cloeziana F.Muell., and in those of a dry inland provenance of Eucalyptus argophloia Blakely. Plants were acclimated at day/night temperatures of 18/13, 23/18, 28/23 and 33/28�C in controlled-temperature glasshouses for 4 months. Light and temperature response curves were measured at the beginning and end of the acclimation period. There were no significant differences in the shape and quantum-yield parameters among provenances at 23, 28 and 33�C day temperatures. Quantum yield [μmol CO2 μmol–1 photosynthetic photon flux density (PPFD)] ranged from 0.04 to 0.06 and the light response shape parameter ranged from 0.53 to 0.78. Similarly, no consistent trends in the rate of dark respiration for plants of each provenance were identified at the four growth temperatures. Average values of dark respiration for the plants of the three provenances ranged from 0.61 to 1.86 μmol m–2 s–1. The optimum temperatures for net photosynthesis increased from 23 to 32�C for the humid- and from 25 to 33�C for the dry-provenance E. cloeziana and from 21 to 33�C for E. argophloia as daytime temperature of the growth environment increased from 18 to 33�C. These results have implications in predicting survival and productivity of E. cloeziana and E. argophloia in areas outside their natural distribution.

Photosynthetic Performance of Two Closely Related Umbilicaria Species in Central Spain: Temperature as a Key Factor

1997 ◽  
Vol 29 (1) ◽  
pp. 67-82 ◽  
Author(s):  
L. G. Sancho ◽  
B. Schroeter ◽  
F. Valladares
Keyword(s):  
Water Content ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Distribution Patterns ◽  
Photon Flux ◽  
Photosynthetic Response ◽  
Central Spain ◽  
Natural Conditions ◽  
Thallus Water Content

AbstractNet photosynthesis (NP) and dark respiration (DR) of thalli of the lichen species Umbilicaria grisea and U. freyi growing together in the same habitat the Sierra de Guadarrama, central Spain, were measured under controlled conditions in the laboratory and under natural conditions in the field over a range of photosynthetic photon flux densities (PPFD), thallus temperatures and thallus water contents. Laboratory experiments revealed that the photosynthetic response to PPFD at optimum thallus water content is very similar in both species. The light compensation points of NP increased from PPFD of c. 20 µmol m−2 s−1 at 0°C up to c. 100 µmol m−2 s−1 PPFD at 25°C. In both species light saturation was not reached up to 700 µmol m−2 s−1 PPFD except at 0°C. By contrast, the temperature dependence of CO2 gas exchange differed substantially between U. grisea and U. freyi. Both species gave significant rates at 0°C. Optimal temperatures of NP were always higher in U. grisea at various PPFD levels if the samples were kept at optimal thallus water content. NP showed maximal rates at 95% dw in U. grisea and 110% dw in U. freyi respectively. In U. grisea a much stronger depression of NP was observed with only 5% of maximal NP reached at 180% dw. At all PPFD and temperature combinations U. freyi showed higher rates of NP and more negative rates of DR if calculated on a dry weight basis. This was also true under natural conditions at the same site, when U. freyi was always more productive than U. grisea. The differences in the photosynthetic response to temperature between both species correlated well with the different distribution patterns of both species. The possibility of genetic control of the physiological performance of these species and its influence on their distribution patterns and autecology is discussed.

Temperature Response of Whole-plant CO2 Exchange Rates of Magnolia (Magnolia grandiflora L.)

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 511d-511
Author(s):  
Marc W. van Iersel ◽  
Orville M. Lindstrom
Keyword(s):  
Dark Respiration ◽  
Temperature Response ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Limiting Factor ◽  
Response Curves ◽  
Gross Photosynthesis ◽  
Temperature Range ◽  
Whole Plant ◽  
Increasing Temperature

Photosynthesis and respiration temperature-response curves are useful in predicting the ability of plants to perform under different environmental conditions. Whole crop CO2 exchange of two groups of magnolia `Greenback' plants was measured over a 26 °C temperature range. Net photosynthesis (Pnet) increased from 2 to 17% C and decreased again at higher temperatures. The Q10 for Pnet decreased from ≈4 at 6 °C to 0.5 at 24 °C. The decrease in Pnet at temperatures over 17 °C was caused by a rapid increase in dark respiration (Rdark) with increasing temperature. The Q10 for Rdark was estimated by fitting an exponential curve to data, resulting in a temperature-independent Q10 of 2.8. Gross photosynthesis (Pgross), estimated as the sum of Rdark and Pnet, increased over the entire temperature range (up to 25 °C). The Q10 for Pgross decreased with increasing temperature, but remained higher than 1. The data suggest that high respiration rates may be the limiting factor for growth of magnolia exposed to high temperatures, since it may result in a net carbon loss from the plants. At temperatures below 5 °C, both Pnet and Rdark become low and the net CO2 exchange of the plants would be expected to be minimal.

scholarly journals Canopy Photosynthesis and Time-of-day Application of Supplemental Light

HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1284-1290 ◽  
Author(s):  
Jakob Markvart ◽  
Eva Rosenqvist ◽  
Helle Sørensen ◽  
Carl-Otto Ottosen ◽  
Jesper M. Aaslyng
Keyword(s):  
Dark Respiration ◽  
High Growth ◽  
Net Photosynthesis ◽  
Time Of Day ◽  
Photon Flux ◽  
Carbon Gain ◽  
Climate Control ◽  
Low Light ◽  
Light Intensities ◽  
Supplemental Lighting

There is increasing use of electricity for supplemental lighting in the northern European greenhouse industry. One reason for this may be to secure a high growth rate during low-light periods by an attempt to increase net photosynthesis. We wanted to clarify which period of the day resulted in the best use of a 5-h supplemental light period for photosynthesis and growth. The periods tested were supplemental light during the night, day, morning, and evening. The experiments were carried out in daylight climate chambers measuring canopy gas exchange. The air temperature was 25 °C and the CO2 level ≈900 ppm. Vegetative chrysanthemum was used, because this species responds quickly to change in light level. The leaf areas of the plant canopies were nondestructively measured each week during the 4-week experimental period. The fact that the quantum yield of photosynthesis is greater at low than at high light intensities favors the use of supplemental light during the dark period, but growth measured as dry weight of the treated plants at the end of the experiments was not significantly different given identical light integrals of the treatments. However, one experiment indicated that increased time with dark hours during day and night (24 h) might decrease net photosynthesis. The assimilation per unit leaf area was approximately the same during times of sunlight through a diffusing screen at 100 μmol·m−2·s−1 of photosynthetic photon flux (PPF) as during times of supplemental (direct) light application at PPF of 200 μmol·m−2·s−1 by high-pressure sodium lamps. We conclude that during the winter and periods of low light intensities, the daily carbon gain does not depend on the time of supplemental light application, but is linked to the total light integral. However, extended time with dark hours during day and night (24 h) might be a disadvantage because of longer periods with dark respiration and subsequent loss of carbon. Our results indicate that during times of low light conditions, it is not necessary to include factors such as the timing of supplemental lighting application to achieve higher net photosynthesis in climate control strategies.

Photosynthetic Productivity of Mayweed Chamomile (Anthemis cotula)

Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 18-26 ◽  
Author(s):  
David R. Gealy ◽  
Sheila A. Squier ◽  
Alex G. Ogg
Keyword(s):  
Pacific Northwest ◽  
Dark Respiration ◽  
Cropping Systems ◽  
Net Photosynthesis ◽  
Compensation Point ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Photosynthetic Productivity ◽  
Maximum Net Photosynthesis

Photosynthetic productivity parameters were determined for mayweed chamomile, a troublesome annual weed of the cropping systems in the Pacific Northwest. At a photosynthetic photon flux density of 1800 μE m−2s–1, maximum net photosynthetic rate of greenhouse-grown plants was 35 mg CO2dm−2h–1and maximum transpiration rate was 6.7 μg H2O cm−2s–1. Dark respiration rate was 1.4 mg CO2dm−2h–1and the light compensation point was 17.5 μE m−2s–1. Carbon dioxide compensation point increased from 25 ppm at 15 C to 43 ppm at 30 C. At saturating photosynthetic photon flux densities, optimum leaf temperature for net photosynthesis was about 25 C. Maximum net photosynthesis of leaves of field-grown plants averaged 15.8 mg CO2dm−2h–1. After a 24-h exposure to 0.075 kg ha–1metribuzin, maximum net photosynthesis and transpiration were reduced 85 and 40%, respectively. Soil water deficits reduced maximum net photosynthesis about 50%.

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 Whole-plant Net CO2 Exchange of Raspberry as Influenced by Air and Root-zone Temperature, CO2 Concentration, Irradiation, and Humidity

1996 ◽  
Vol 121 (5) ◽  
pp. 838-845 ◽  
Author(s):  
David C. Percival ◽  
J.T.A. Proctor ◽  
M.J. Tsujita
Keyword(s):  
Root Zone ◽  
Dark Respiration ◽  
Saturated Vapor ◽  
Environmental Parameters ◽  
Net Photosynthesis ◽  
Rubus Idaeus ◽  
Root Zone Temperature ◽  
Whole Plant ◽  
Zone Temperature ◽  
Model Variation

The influence of irradiance, CO2, and temperature on whole-plant net CO2 exchange rate (NCER) of Rubus idaeus L. `Heritage' micropropagated raspberries was examined. Within the set of environmental conditions examined, irradiation was the most important factor, accounting for 58% of the whole-plant irradiance/CO2 concentration/temperature NCER model variation, followed by CO2 concentration (28%) and temperature (2.5%). Net photosynthesis (Pn) required irradiance levels >600 μmol·m-2·s-1 PPF for saturation, greatly increased under CO2 enrichment (up to 1500 μL·L-1), and was optimum at a whole-plant temperature of 20 °C. Temperature effects were partitioned in an experiment using varying air and root-zone temperatures (15, 20, 25, 30, and 35 °C) under saturated light and ambient CO2 levels (350 μL·L-1). Air and root-zone temperature influenced Pn, with maximum rates occurring at an air × root-zone temperature of 17/25 °C. The contribution of air and root-zone temperature to the NCER model varied, with air and root-zone temperature contributing 75% and 24%, respectively, to the total model variation (R2 = 0.96). Shoot dark respiration increased with air and root-zone temperature, and root respiration rates depended on air and root-zone temperature and shoot assimilation rate. Humidity also influenced Pn with a saturated vapor pressure deficit threshold >0.25 kPa resulting in a Pn decrease. Quantifying the physiological response of raspberries to these environmental parameters provides further support to recent findings that cool shoot/warm root conditions are optimum for raspberry plant growth.

scholarly journals Heat Tolerance of Selected Species and Populations of Rhododendron

1995 ◽  
Vol 120 (3) ◽  
pp. 423-428 ◽  
Author(s):  
Thomas G. Ranney ◽  
Frank A. Blazich ◽  
Stuart L. Warren
Keyword(s):  
Heat Tolerance ◽  
Leaf Surface ◽  
Dark Respiration ◽  
Temperature Response ◽  
Net Photosynthesis ◽  
Tissue Weight ◽  
Unit Leaf ◽  
Leaf Surface Area ◽  
Temperature Optima ◽  
Two Populations

Temperature sensitivity of net photosynthesis (PN) was evaluated among four taxa of rhododendron including Rhododendron hyperythrum Hayata, R. russatum Balf. & Forr., and plants from two populations (northern and southern provenances) of R. catawbiense Michx. Measurements were conducted on leaves at temperatures rauging from 15 to 40C. Temperature optima for PN ranged from a low of 20C for R. russatum to a high of 25C for R. hyperythrum. At 40C, PN rates for R. hyperythrum, R. catawbiense (northern provenance), R. catawbiense (southern provenance), and R. russatum were 7.8,5.7,3.5, and 0.2 μmol·m-2·s-1, respectively (LSD0.05 = 1.7). Rhododendron catawbiense from the southern provenance did not appear to have greater heat tolerance than plants from the northern provenance. Differences in dark respiration among taxa were related primarily to differences in tissue weight per unit leaf surface area. Temperature coefficients (Q5) for respiration did not vary in temperature response among taxa. Differences in heat tolerance appeared to result from a combination of stomatal and nonstomatal limitations on PN at high temperatures.

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