Stomatal Metabolism: CO2 Fixation and Respiration

1977 ◽  
Vol 4 (4) ◽  
pp. 611
Author(s):  
N Thorpe ◽  
F.L Milthorpe
Keyword(s):  
Flux Density ◽  
Co2 Fixation ◽  
Calvin Cycle ◽  
Co2 Concentration ◽  
High Rate ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Initial Fixation ◽  
Sugar Phosphates ◽  
Early Fixation

The rate of fixation of CO2 by epidermis attached to the leaf of Commelina cyanea was linear with photon flux density up to 1.08 mE m-� s-� and with CO2 concentration from 0 to 355 ppm. Detached epidermis, on the other hand, showed no response to photon flux density and had rates in the light which were only twice those in the dark. There was substantial leakage of all labelled methanol-soluble substances from isolated epidermis. Its apparent reduced functioning may well be associated with this leakage rather than reflecting transport from the mesophyll. The early fixation products in light and dark were similar in attached and detached epidermis. These were mainly aspartate and malate in contrast to the Calvin cycle intermediates formed in mesophyll in the light. It seems likely that phosphoenolpyruvate carboxylase is closely implicated in the initial fixation of CO2 by stomata and is responsible for the much higher rates of fixation per unit of chlorophyll by epidermis than by mesophyll. Although aspartate and malate are the major products detectable after 2 min feeding with 14CO2 and remain as a high proportion of labelled products during a subsequent 12CO2 chase, amino acids, sugars and sugar phosphates together with polysaccharides and other methanol-insoluble products are eventually labelled. Attempts to measure respiration rates of attached epidermis were unsuccessful due to fixation of mesophyll-respired CO2; the rate in detached epidermis was high, suggesting a high rate of turnover of carbon products by stomata, but we were unable to relate this to rates in attached epidermis. Rates were higher in CO2-free than in CO2-containing environments, indicating a possible explanation of the CO2 effect on stomata.

scholarly journals Enhanced Chlorella vulgaris Buitenzorg growth by Photon Flux Density Alteration in Serial Bubble Column Photobioreactors

2007 ◽  
Vol 7 (1 & 2) ◽  
pp. 89 ◽  
Author(s):  
Anondho Wijanarko ◽  
Dianursanti Antonius Yudi Sendjaya ◽  
Misri Gozan ◽  
Roekmijati Widaningroem Soemantojo ◽  
Arief Budi Witarto ◽  
...  
Keyword(s):  
Flux Density ◽  
Biomass Production ◽  
Chlorella Vulgaris ◽  
Co2 Fixation ◽  
Bubble Column ◽  
Operating Conditions ◽  
Industrial Plant ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Halogen Lamp

Micro algae are photolitotrophs that perform oxygenic photosynthesis and capable of accumulating a large amount of CO2, using an inducible CO2 concentrating mechanism (CCM). These characteristics make the micro algae potentially useful for removal and utilization of CO2 emitted from industrial plant. Generally, the usage of photosynthetic microorganism in CO2 fixation and biomass production for the economically viable commodities have been increased and significantly improved as a solution for this problem. Using these facts and previous research results using Anabaena cylindrica IAM M1 and Spirulina platensis IAM M 135, enhancement of CO2 fixation and biomass production by Chlorella vulgaris Buitenzorg with photon flux density alteration along with an increasing of culture biomass during the cellular growth period, was implemented in this research. The photon flux density used in this alteration was the maximum light for Chlorella’s maximum growth rate ( I mmax,opt ). The cultivation of Chlorella vulgaris Buitenzorg in the Benneck basal medium operating conditions: T, 29oC; P, 1.0 atm; UG, 2.4m/h; CO2, 10%; using Philip Halogen Lamp 20W/12V/50Hz as the light source and three bubble column photobioreactors arranged in series order with each having a volume of 0.200dm3. Results had shown that the photon flux density alteration as a whole could increase around 60% the biomass production of Chlorella vulgaris and around 7% the CO2 fixation ability, compared to constant photon flux density outcomes. This experiment also showed that the noncompetitive inhibition of [HCO3-] as carbon source substrate is affected significantly during the cultivation in both of alteration and continuous photon flux density.

scholarly journals Estimation of Global and Diffuse Photosynthetic Photon Flux Density under Various Sky Conditions Using Ground-Based Whole-Sky Images

2019 ◽  
Vol 11 (8) ◽  
pp. 932
Author(s):  
Megumi Yamashita ◽  
Mitsunori Yoshimura
Keyword(s):  
Flux Density ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Diffuse Component ◽  
Photosynthetic Photon Flux ◽  
Physiological Processes ◽  
Sky Conditions ◽  
Mean Square Errors ◽  
Relative Root

A knowledge of photosynthetic photon flux density (PPFD: μmol m−2 s−1) is crucial for understanding plant physiological processes in photosynthesis. The diffuse component of the global PPFD on a short timescale is required for the accurate modeling of photosynthesis. However, because the PPFD is difficult to determine, it is generally estimated from incident solar radiation (SR: W m−2), which is routinely observed worldwide. To estimate the PPFD from the SR, photosynthetically active radiation (PAR: W m−2) is separated from the SR using the PAR fraction (PF; PAR/SR: unitless), and the PAR is then converted into the PPFD using the quanta-to-energy ratio (Q/E: μmol J−1). In this procedure, PF and Q/E are considered constant values; however, it was reported recently that PF and Q/E vary under different sky conditions. Moreover, the diffuse ratio (DR) is needed to distinguish the diffuse component in the global PAR, and it is known that the DR varies depending on sky conditions. Ground-based whole-sky images can be used for sky-condition monitoring, instead of human-eye interpretation. This study developed a methodology for estimating the global and diffuse PPFD using whole-sky images. Sky-condition factors were derived through whole-sky image processing, and the effects of these factors on the PF, the Q/E of global and diffuse PAR, and the DR were examined. We estimated the global and diffuse PPFD with instantaneous values using the sky-condition factors under various sky conditions, based on which the detailed effects of the sky-condition factors on PF, Q/E, and DR were clarified. The results of the PPFD estimations had small bias errors of approximately +0.3% and +3.8% and relative root mean square errors of approximately 27% and 20% for the global and diffuse PPFD, respectively.

scholarly journals Influences of Shading and Fall Fertilization on Fluorescence, Freeze Resistance, Flower Production and Growth of Rhododendron ×kurume ‘Pink Pearl’

2012 ◽  
Vol 30 (1) ◽  
pp. 28-34
Author(s):  
Frank P. Henning ◽  
Timothy J. Smalley ◽  
Orville M. Lindstrom ◽  
John M. Ruter
Keyword(s):  
Light Intensity ◽  
Dry Weight ◽  
Fertilizer Application ◽  
High Rate ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Freeze Resistance ◽  
Time Period ◽  
Shade Cloth ◽  
Main Plot

We investigated the influences of fall fertilization and light intensity on photosynthesis and freeze resistance of Rhododendron ×kurume ‘Pink Pearl’, an evergreen azalea cultivar, grown outdoors in containers under nursery conditions. The study included two main-plot fall fertilization treatments: 1) 0.5 liter solution containing 75 mg·liter−1 N applied for 60 days from August 1 through September 29 and 2) 0.5 liter solution containing 125 mg·liter−1 N applied for 120 days from August 1 through November 28, and four subplot light intensity treatments 1) 100% ambient photon flux density (PPFD) from May 1, 2004, through May 1, 2005, 2) shade fabric rated to reduce PPFD by 50% from May 1 through September 30, 2004, followed by 100% PPFD from October 1, 2004, through May 1, 2005, 3) 100% PPFD from May 1 through September 30, 2004, followed by 50% PPFD from October 1, 2004, through May 1, 2005, and 4) 50% PPFD from May 1, 2004, through May 1, 2005. Fertilizer application and shade treatments did not interact in their effects on stem freeze resistance or the timing of anthesis. The high rate of extended fertigation (125 mg·liter−1 N applied August 1 through September 28) reduced freeze resistance of azalea stems and advanced anthesis by 4.9 days compared to plants that received moderate fertigation (75 mg·liter−1 N from August 1 through September 29). The high rate of extended fall fertigation failed to increase leaf or stem dry weight compared to plants that received the moderate rate of fertigation. Plants grown in 50% PPFD from May 1 through September 30 produced 163% more above ground dry weight compared to plants grown in 100% light during the same time period. The addition or removal of shade cloth beginning October 1 failed to enhance azalea stem freeze resistance compared to plants that were only exposed to 100 or 50% PPFD respectively. Shade treatments affected the chlorophyll fluorescence ratio (Fv · Fm−1) of leaves, but leaf fluorescence was unrelated to stem freeze resistance. Shade treatments affected azalea growth and photosynthetic stress, but shade neither interacted with fall fertilization to increase stem freeze resistance, nor had a biologically significant effect on stem freeze resistance.

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