Instruments for the Measurement of Photosynthetically Active Radiation and Red, Far-Red and Blue Light

1983 ◽  
Vol 20 (1) ◽  
pp. 103 ◽  
Author(s):  
F. I. Woodward
Keyword(s):  
Blue Light ◽  
Photosynthetically Active Radiation ◽  
Active Radiation

Guard cells in albino leaf patches do not respond to photosynthetically active radiation, but are sensitive to blue light, CO2 and abscisic acid

2006 ◽  
Vol 29 (8) ◽  
pp. 1595-1605 ◽  
Author(s):  
M. ROB G. ROELFSEMA ◽  
KAI R. KONRAD ◽  
HOLGER MARTEN ◽  
GEORGE K. PSARAS ◽  
WOLFRAM HARTUNG ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Blue Light ◽  
Photosynthetically Active Radiation ◽  
Guard Cells ◽  
Active Radiation

scholarly journals PHOTOSYNTHESIS STUDIES OF TOMATO TRANSPLANTS SUBJECTED TO VARIOUS LIGHT SOURCES.

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 582b-582
Author(s):  
Stephanie Brown ◽  
Alejandro Ching
Keyword(s):  
Blue Light ◽  
Photosynthetically Active Radiation ◽  
Root Biomass ◽  
Yield Potential ◽  
Natural Light ◽  
Light Sources ◽  
Harvest Time ◽  
Active Radiation ◽  
The Third ◽  
Red Color

A photosynthesis study was conducted on seedlings of Lycopersicon esculentum L. cv. “Traveller 76” subjected to natural, clear, blue and red color irradiations to predict and evaluate harvest time and yield potential. Photosynthesis (PS) rates were higher on clear and red irradiated transplants with 16.1 and 12.4 μMol/m2/s, respectively, for two weeks of treatment. Blue irradiation showed lowest PS rate with 2.2 μMol/m2/s. For the third and fourth weeks of treatment, PS rate increased to 10.9 and 13.5 μMol/m2/s, respectively, on blue light treated transplants, while red, clear and natural light treatments decreased. CO2 appears to be lowest at high PS rate under these treatments. Transplants treated with blue and red lights were taller and thicker around the stem. Clear and natural lights were shorter, but with a larger root biomass. PAR (Photosynthetically Active Radiation) was highest at noon under open natural light with 1108.8 μE/s/m2, but also high for blue, red and clear lights when compared to earlier or later time. The lowest PAR was shown for blue and red lights.

Spectral Distribution of Photosynthetically Active Radiation in some South-eastern Australian Waters

1979 ◽  
Vol 30 (1) ◽  
pp. 81 ◽  
Author(s):  
JTO Kirk
Keyword(s):  
Blue Light ◽  
Photosynthetically Active Radiation ◽  
Spectral Distribution ◽  
Light Attenuation ◽  
Red Light ◽  
Extreme Case ◽  
Euphotic Zone ◽  
Active Radiation ◽  
South Eastern ◽  
Eastern Australia

The results are presented of a study of the spectral distribution of photosynthetically active radiation (PAR) in some inland, and one coastal, waters in south-eastern Australia, carried out with a submersible spectroradiometer. There is particularly rapid attenuation with depth of blue light in the 400-500-nm waveband, due to the yellow substances ('gilvin', 'gelbstoff') in the waters. Attenuation in the red region, due to absorption by water itself, is clearly evident but is generally much less steep than that in the blue. Within the rather shallow euphotic zone typical of these waters the available PAR is impoverished in blue light but still contains plenty of red (630-700-nm) light. At greater depths, in waters of moderate turbidity, a spectral distribution strongly peaked at about 580 nm, with a shoulder at about 630 nm, is obtained. Although the contribution of phytoplankton can be significant, in general in these turbid inland waters suspended soil particles contribute more to vertical light attenuation. This is partly due to the increased pathlength of the photons caused by scattering, but direct absorption of light, especially in the blue region, by the particulate inanimate 'tripton' is suggested by the data. Turbidity and dis- solved colour of the water tend to increase together: in particularly turbid, yellow waters the spectral distribution of PAR is shifted to longer wavelengths and in an extreme case consisted of quite a sharp peak at 700 nm. In the clear, comparatively colourIess coastal-estuarine waters of Batemans Bay (N.S.W.), blue light was attenuated less steeply than red light, so that the underwater spectral distribution, although peaked at about 570 nm, was (at 4 m) still quite rich in blue as well as red light.

scholarly journals A microbiota–root–shoot circuit favours Arabidopsis growth over defence under suboptimal light

Nature Plants ◽  
2021 ◽  
Author(s):  
Shiji Hou ◽  
Thorsten Thiergart ◽  
Nathan Vannier ◽  
Fantin Mesny ◽  
Jörg Ziegler ◽  
...  
Keyword(s):  
Stress Responses ◽  
Photosynthetically Active Radiation ◽  
Bacterial Community Composition ◽  
Light Condition ◽  
Long Distance ◽  
Active Radiation ◽  
Light Manipulation ◽  
Growth Deficiency ◽  
Dependent Growth ◽  
Control Light

AbstractBidirectional root–shoot signalling is probably key in orchestrating stress responses and ensuring plant survival. Here, we show that Arabidopsis thaliana responses to microbial root commensals and light are interconnected along a microbiota–root–shoot axis. Microbiota and light manipulation experiments in a gnotobiotic plant system reveal that low photosynthetically active radiation perceived by leaves induces long-distance modulation of root bacterial communities but not fungal or oomycete communities. Reciprocally, microbial commensals alleviate plant growth deficiency under low photosynthetically active radiation. This growth rescue was associated with reduced microbiota-induced aboveground defence responses and altered resistance to foliar pathogens compared with the control light condition. Inspection of a set of A. thaliana mutants reveals that this microbiota- and light-dependent growth–defence trade-off is directly explained by belowground bacterial community composition and requires the host transcriptional regulator MYC2. Our work indicates that aboveground stress responses in plants can be modulated by signals from microbial root commensals.

scholarly journals Intercepted Photosynthetically Active Radiation (PAR) and Spatial and Temporal Distribution of Transmitted PAR under High-Density and Super High-Density Olive Orchards

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 351
Author(s):  
Adolfo Rosati ◽  
Damiano Marchionni ◽  
Dario Mantovani ◽  
Luigi Ponti ◽  
Franco Famiani
Keyword(s):  
Spatial Variability ◽  
Photosynthetically Active Radiation ◽  
Temporal Distribution ◽  
High Density ◽  
Radiation Use Efficiency ◽  
Spatial And Temporal Distribution ◽  
Active Radiation ◽  
Use Efficiency ◽  
And Performance ◽  
Radiation Use

We quantified the photosynthetically active radiation (PAR) interception in a high-density (HD) and a super high-density (SHD) or hedgerow olive system, by measuring the PAR transmitted under the canopy along transects at increasing distance from the tree rows. Transmitted PAR was measured every minute, then cumulated over the day and the season. The frequencies of the different PAR levels occurring during the day were calculated. SHD intercepted significantly but slightly less overall PAR than HD (0.57 ± 0.002 vs. 0.62 ± 0.03 of the PAR incident above the canopy) but had a much greater spatial variability of transmitted PAR (0.21 under the tree row, up to 0.59 in the alley center), compared to HD (range: 0.34–0.43). This corresponded to greater variability in the frequencies of daily PAR values, with the more shaded positions receiving greater frequencies of low PAR values. The much lower PAR level under the tree row in SHD, compared to any position in HD, implies greater self-shading in lower-canopy layers, despite similar overall interception. Therefore, knowing overall PAR interception does not allow an understanding of differences in PAR distribution on the ground and within the canopy and their possible effects on canopy radiation use efficiency (RUE) and performance, between different architectural systems.

scholarly journals Estimation of Incident Photosynthetically Active Radiation from GOES Visible Imagery

2008 ◽  
Vol 47 (3) ◽  
pp. 853-868 ◽  
Author(s):  
Tao Zheng ◽  
Shunlin Liang ◽  
Kaicun Wang
Keyword(s):  
Photosynthetically Active Radiation ◽  
Terrestrial Ecosystem ◽  
New Method ◽  
High Temporal Resolution ◽  
Atmospheric Conditions ◽  
Ecosystem Models ◽  
Surface Conditions ◽  
Active Radiation ◽  
Ground Measurement ◽  
Visible Imagery

Abstract Incident photosynthetically active radiation (PAR) is an important parameter for terrestrial ecosystem models. Because of its high temporal resolution, the Geostationary Operational Environmental Satellite (GOES) observations are very suited to catch the diurnal variation of PAR. In this paper, a new method is developed to derive PAR using GOES data. What makes this new method distinct from the existing method is that it does not need external knowledge of atmospheric conditions. The new method retrieves both atmospheric and surface conditions using only at-sensor radiance through interpolation of time series of observations. Validations against ground measurement are carried out at four “FLUXNET” sites. The values of RMSE of estimated and ground-measured instantaneous PAR at the four sites are 130.71, 131.44, 141.16, and 190.22 μmol m−2 s−1, respectively. At the four validation sites, the RMSE as the percentage of estimated mean PAR value are 9.52%, 13.01%, 13.92%, and 24.09%, respectively; the biases are −101.54, 16.56, 11.09, and 53.64 μmol m−2 s−1, respectively. The independence of external atmospheric information enables this method to be applicable to many situations in which external atmospheric information is not available. In addition, topographic impacts on surface PAR are examined at the 1-km resolution at which PAR is retrieved using the GOES visible band data.

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