scholarly journals Carboxylation Capacity Can Limit C3 Photosynthesis at Elevated CO2 throughout Diurnal Cycles

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2603
Author(s):  
James Bunce
Keyword(s):  
Elevated Co2 ◽  
Carbon Fixation ◽  
Leaf Gas Exchange ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Early Morning ◽  
C3 Plants ◽  
Lablab Purpureus ◽  
Diurnal Cycles ◽  
Air Temperatures

The response of carbon fixation in C3 plants to elevated CO2 is relatively larger when photosynthesis is limited by carboxylation capacity (VC) than when limited by electron transport (J). Recent experiments under controlled, steady-state conditions have shown that photosynthesis at elevated CO2 may be limited by VC even at limiting PPFD. These experiments were designed to test whether this also occurs in dynamic field environments. Leaf gas exchange was recorded every 5 min using two identical instruments both attached to the same leaf. The CO2 concentration in one instrument was controlled at 400 μmol mol−1 and one at 600 μmol mol−1. Leaves were exposed to ambient sunlight outdoors, and cuvette air temperatures tracked ambient outside air temperature. The water content of air in the leaf cuvettes was kept close to that of the ambient air. These measurements were conducted on multiple, mostly clear days for each of three species, Glycine max, Lablab purpureus, and Hemerocallis fulva. The results indicated that in all species, photosynthesis was limited by VC rather than J at both ambient and elevated CO2 both at high midday PPFDs and also at limiting PPFDs in the early morning and late afternoon. During brief reductions in PPFD due to midday clouds, photosynthesis became limited by J. The net result of the apparent deactivation of Rubisco at low PPFD was that the relative stimulation of diurnal carbon fixation at elevated CO2 was larger than would be predicted when assuming limitation of photosynthesis by J at low PPFD.

scholarly journals Carboxylation Capacity Can Limit Photosynthesis at Elevated CO2 throughout Diurnal Cycles

2021 ◽  
Author(s):  
James Bunce
Keyword(s):  
Elevated Co2 ◽  
Carbon Fixation ◽  
Leaf Gas Exchange ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Early Morning ◽  
C3 Plants ◽  
Lablab Purpureus ◽  
Diurnal Cycles ◽  
Air Temperatures

The response of carbon fixation in C3 plants to elevated CO2 is relatively larger when photosynthesis is limited by carboxylation capacity (VC) than when limited by electron transport (J). Recent experiments under controlled, steady-state conditions have shown that photosynthesis at elevated CO2 may be limited by VC even at limiting PPFD. These experiments were designed to test whether this also occurs in dynamic field environments. Leaf gas exchange was recorded every 5 minutes using two identical instruments both attached to the same leaf. The CO2 concentration in one instrument was controlled at 400 mol mol-1 and one at 600 mol mol-1. Leaves were exposed to ambient sunlight outdoors, and cuvette air temperatures tracked ambient outside air temperature. The water content of air in the leaf cuvettes was kept close to that of the ambient air. These measurements were conducted on multiple, mostly clear days for each of three species, Glycine max, Lablab purpureus, and Hemerocallis fulva. The results indicated that in all species, photosynthesis was limited by VC rather than J at both ambient and elevated CO2 both at high midday PPFDs and also at limiting PPFDs in the early morning and late afternoon. During brief reductions in PPFD due to midday clouds, photosynthesis became limited by J, The net result of the apparent deactivation of Rubisco at low PPFD was that the relative stimulation of diurnal carbon fixation at elevated CO2 was larger than would be predicted when assuming limitation of photosynthesis by J at low PPFD.

scholarly journals Photosynthetic performance of rock-colonising lichens in the Mountain Zebra National Park, South Africa

Koedoe ◽  
1993 ◽  
Vol 36 (1) ◽  
Author(s):  
Dirk Wessels ◽  
Ludger Kappen
Keyword(s):  
South Africa ◽  
Volcanic Rock ◽  
National Park ◽  
Ambient Air ◽  
Early Morning ◽  
Photosynthetic Performance ◽  
The Other ◽  
Air Temperatures ◽  
Desert Regions

The photosynthetic behaviour of endolithic andepilithic lichens characteristic of sedimentary and volcanic rock was investigated in situ in the Mountain Zebra National Park, South Africa. The park forms part of an inland semi-desert known as the Karoo, in the Cape Province. Temperatures within Balfour sandstone were monitored, the results showing that during the early morning, temperatures within the sandstone were nearly 5@C lower than ambient air temperatures. This may enhance the frequency of water condensing on the sandstone, which may be particularly important for the endoliths Leciclea aff. sarcogynoides and Sarcogyne cf. austroafricana. Maximum photosynthetic rates of the investigated species were found at temperatures between 20@C and 30@C, far higher than the recorded optimum temperatures for lichens from temperate and desert regions. Parmelia chlorea was the most productive species. Compared to the other epiliths, Peltula capensis was found to be a moderately productive species. The photosynthetic gain of Leciclea aff. sarcogynoides and Sarcogyne cf. austro-africana was low, but the photosynthetic gain of these two species still exceeded that of Acarospora sp.

scholarly journals Growth Efficiency of Greengram (Vigna radiata L. Wilczek) Under Elevated Carbondioxide Condition

2020 ◽  
pp. 58-73
Author(s):  
Tarique Aziz ◽  
Ranjan Das ◽  
Sangita Das
Keyword(s):  
Elevated Co2 ◽  
Growth Parameters ◽  
Genotypic Variation ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Green Gram ◽  
C3 Plants ◽  
Nodule Formation ◽  
Total Biomass ◽  
Agricultural Crop

The CO2 concentration in the atmosphere is rising and anticipated to be doubled by the end of the current century. Agricultural crop production is one of the key sectors that might be affected by rising atmospheric CO2 through its effect on photosynthetic rates and thus productivity. It was reported that C3 plants respond to elevated CO2 by modification of morpho-physiological traits. The crop selected for the present study was Green gram (Vigna radiate L. Wilczek). Though it is an important crop, the availability of pulses has declined. So, a study of the plant responses to high atmospheric CO2 is important since it regulates productivity and quality. Moreover information about genotypic variation of crops under elevated CO2 is lacking in legumes. The general aim of the study is test whether Green gram can adapt to such a change and to explore mechanisms underlining the adaptive response. Six genotypes of green gram used in the study were SML1827, SML832, SML1831, PM1533, Pusa M-19-31, and Pant M-5. Three different levels of CO2 concentration namely 390ppm, 600 ppm and 750ppm under open top chambers along with an ambient concentration were maintained to assess the response of growth, physiological and yield parameters. The purpose of Open Top Chamber was to study the response of plants in high CO2 environment with precise control and regulation of desired CO2, temperature and humidity. The results obtained for this experiment showed that elevated CO2 has a positive effect on crop growth and development. Results indicated that 600ppm CO2 enhanced some growth parameters viz. leaf area, number of branches per plant, number of effective root nodules and total biomass of plant which ultimately influenced the yield. Under 750 ppm CO2, An opposite trend was recorded where yield was significantly reduced. Genotypes like Pant M-5, Pusa M-19-31 could be considered as better genotypes when grown under elevated levels of CO2 as they have better N acquisition capability because of greater nodule formation in addition to biomass accumulation. Therefore, such genotypes may be utilized as future breeding materials for adaptation to the changed climatic condition.

Thermogenic flowering of taro (Colocasia esculenta, Araceae)

2004 ◽  
Vol 82 (11) ◽  
pp. 1557-1565 ◽  
Author(s):  
Anton Ivancic ◽  
Vincent Lebot ◽  
Olivier Roupsard ◽  
José Quero Garcia ◽  
Tom Okpul
Keyword(s):  
Ambient Air ◽  
Early Morning ◽  
Colocasia Esculenta ◽  
Critical Periods ◽  
Final Phase ◽  
Inflorescence Development ◽  
Air Temperatures ◽  
Female Phase ◽  
Male Phase ◽  
The Mean

Thermogenesis and its association with taro (Colocasia esculenta (L.) Schott) flowering was studied during the warmest period of the year (December 2002 – February 2003) within a large collection of heterogeneous plant material on Espiritu Santo, Vanuatu. On each studied inflorescence, temperatures of the three main parts of the spadix and the ambient air were recorded during a period of 38 h. The investigation indicates that significant thermogenic activity of taro inflorescences takes place during two successive nights: (1) during the night when an inflorescence becomes odorous (the female phase) and (2) a night later, when microsporogenesis approaches its final phase (the male phase). The highest average difference between mean temperatures of the ambient air and inflorescences were documented during the female phase, at 0500 hours (the mean temperature of the sterile appendix was 29.1 ± 0.9 °C (P = 0.05) and this was 6.8 °C above the temperature of the ambient air). Thermogenic activity is synchronized with the protogynous nature of the species and insect pollination in the early morning hours. Its main putative functions are (1) to reduce the deviations of ambient air temperatures during the most critical periods of flowering, and (2) to promote cross-pollination. It stops 1–1.5 h after pollen has been released.Key words: taro, Colocasia esculenta, thermogenesis, inflorescence development, pollination.

scholarly journals Relationships between climate of origin and photosynthetic responses to an episodic heatwave depend on growth CO2 concentration for Eucalyptus camaldulensis var. camaldulensis

2017 ◽  
Vol 44 (11) ◽  
pp. 1053 ◽  
Author(s):  
Michael E. Loik ◽  
Víctor Resco de Dios ◽  
Renee Smith ◽  
David T. Tissue
Keyword(s):  
Elevated Co2 ◽  
Eucalyptus Camaldulensis ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Interactive Effects ◽  
Multiple Control ◽  
Air Temperatures ◽  
Eastern Australia ◽  
Photosynthetic Responses ◽  
Eucalyptus Camaldulensis Dehnh

Stressful episodic weather is likely to affect the C balance of trees as the climate changes, potentially altering survival. However, the role of elevated CO2 concentration ([CO2]) in tolerating off-season episodic extremes is not clear. We tested for interactive effects of elevated CO2 and springtime heat stress on photosynthesis for seven genotypes of Eucalyptus camaldulensis Dehnh. var. camaldulensis, representing its widespread distribution across south-eastern Australia. We grew clonal material under glasshouse conditions of ambient (aCO2; 400 parts per million (ppm)) or elevated (eCO2; 640 ppm) [CO2], and air temperatures of 25 : 17°C (day : night), and measured the electron transport rate in PSII (ETR), stomatal conductance to water vapour (gs) and net CO2 assimilation (A). Measurements were made before, during and after a four-day temperature excursion of 35 : 27°C. ETR and A were ~17% higher for plants grown in eCO2 than in aCO2. Photosynthesis remained stable for plants in eCO2 during the heatwave. Based on the effect size ratio (eCO2 : aCO2), gs and ETR were temporarily affected more by the heatwave than A. A reduction in ETR in eCO2 was the only lasting effect of the heatwave. There were no significant differences among genotypes. Correlations between photosynthesis and climate of origin differed for plants grown in aCO2 compared with eCO2, suggesting potential complex and multiple control points on photosynthesis.

scholarly journals Ocean acidification mediates photosynthetic response to UV radiation and temperature increase in the diatom <i>Phaeodactylum tricornutum</i>

2012 ◽  
Vol 9 (10) ◽  
pp. 3931-3942 ◽  
Author(s):  
Y. Li ◽  
K. Gao ◽  
V. E. Villafañe ◽  
E. W. Helbling
Keyword(s):  
Ocean Acidification ◽  
Elevated Co2 ◽  
Uv Radiation ◽  
Phaeodactylum Tricornutum ◽  
Carbon Fixation ◽  
Co2 Concentration ◽  
Photochemical Quenching ◽  
Fixation Rate ◽  
Ps Ii ◽  
Temperature Levels

Abstract. Increasing atmospheric CO2 concentration is responsible for progressive ocean acidification, ocean warming as well as decreased thickness of upper mixing layer (UML), thus exposing phytoplankton cells not only to lower pH and higher temperatures but also to higher levels of solar UV radiation. In order to evaluate the combined effects of ocean acidification, UV radiation and temperature, we used the diatom Phaeodactylum tricornutum as a model organism and examined its physiological performance after grown under two CO2 concentrations (390 and 1000 μatm) for more than 20 generations. Compared to the ambient CO2 level (390 μatm), growth at the elevated CO2 concentration increased non-photochemical quenching (NPQ) of cells and partially counteracted the harm to PS II (photosystem II) caused by UV-A and UV-B. Such an effect was less pronounced under increased temperature levels. The ratio of repair to UV-B induced damage decreased with increased NPQ, reflecting induction of NPQ when repair dropped behind the damage, and it was higher under the ocean acidification condition, showing that the increased pCO2 and lowered pH counteracted UV-B induced harm. As for photosynthetic carbon fixation rate which increased with increasing temperature from 15 to 25 °C, the elevated CO2 and temperature levels synergistically interacted to reduce the inhibition caused by UV-B and thus increase the carbon fixation.

scholarly journals Photosynthesis of Sago Palm (Metroxylon sagu Rottb.) Seedling at Different Air Temperatures

2017 ◽  
Author(s):  
Aidil Azhar ◽  
Daigo Makihara ◽  
Hitoshi Naito ◽  
Hiroshi Ehara
Keyword(s):  
Chlorophyll Content ◽  
Air Temperature ◽  
Photosynthetic Activity ◽  
Leaf Gas Exchange ◽  
Ambient Air ◽  
Photosynthetic Parameters ◽  
Sago Palm ◽  
Ambient Air Temperature ◽  
Air Temperatures ◽  
Metroxylon Sagu

Photosynthetic activities of the sago palm (Metroxylon sagu Rottb.) were studied to find out its sensitivity to changes in ambient air temperature. The minimum ambient air temperature designed for the experiment was 25&ndash;29⁰C, while the higher end was 29&ndash;33⁰C. Several photosynthetic parameters were studied to support our analysis in sago photosynthetic activity, including diurnal leaf gas exchange, assimilation rate vs. CO2 concentration, leaf greenness, leaf chlorophyll content, and photosynthetic rate vs. irradiance. We found that sago palm photosynthetic activity tends to be more sensitive to minimum than to maximum ambient air temperature. The plants exposed to higher air temperatures had dark green leaf color associated with higher rates of diurnal photosynthesis, chlorophyll content, and rubisco limited photosynthetic activity. They also exhibited higher trend in optimum irradiance absorption level. Consequently, maximum light energy dissipation occurred at higher temperatures.

Rising [CO2] changes competition relationships between native woody and alien herbaceous Cerrado species

2018 ◽  
Vol 45 (8) ◽  
pp. 854 ◽  
Author(s):  
Nayara M. J. Melo ◽  
Rayete S.-E. G. Rosa ◽  
Eduardo G. Pereira ◽  
João Paulo Souza
Keyword(s):  
Leaf Area ◽  
Elevated Co2 ◽  
Leaf Gas Exchange ◽  
Woody Species ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Growth Patterns ◽  
Grass Species ◽  
Herbaceous Species ◽  
Ecophysiological Responses

The structure of the Cerrado may be explained by the competition between woody and herbaceous species. However, the rising CO2 concentration ([CO2]) predicted under current climatic change may modify the ecophysiological responses of woody and herbaceous species owing to functional traits of each group, which may in turn modify vegetation structure as competitive relationships change among species. In this study we examined ecophysiological responses and competition between two cerrado species under elevated [CO2]. We selected an herbaceous alien grass (Melinis minutiflora P. Beauv.) and an endemic woody cerrado species (Hymenaea stigonocarpa Mart. ex Hayne). Hymenaea stigonocarpa individuals were maintained in three plots with different M. minutiflora densities: 0, 50 and 100% in two different [CO2] (380 ppm and 700 ppm) in open-top chambers. Leaf gas exchange, effective quantum efficiency of PSII, chlorophyll content, and growth increased in H. stigonocarpa plants under high [CO2]. The competition with M. minutiflora under elevated [CO2] led to an increase in specific leaf area, leaf area ratio and biomass allocation to shoots in H. stigonocarpa. In contrast, M. minutiflora had a delayed leaf development and high stem dry mass under elevated [CO2]. These changes in growth patterns under elevated [CO2] will modify allocation of resources, improving the competition potential of the woody species over the alien grass species in the Cerrado.

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