scholarly journals Effect of blue and red radiation on cycling stomata of bean.

1973 ◽  
Vol 21 (2) ◽  
pp. 117-123
Author(s):  
P.A.M. Hopmans
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Guard Cells ◽  
Radiant Flux ◽  
Stomatal Behaviour ◽  
Blue Radiation ◽  
Quantum Flux ◽  
Permeability For Water ◽  
Red Radiation ◽  
Blue And Red Radiation

Differences in the effect of blue and red radiation of low radiant flux density on sustained stomatal cycling were studied in Phaseolus vulgaris cv. Vroege Wagenaar. Stomatal behaviour in a constant environment was observed indirectly by recording the differences between leaf and air temperature. In radiation with equal radiant flux densities of 1.75 W/m2 and with equal estimated absorbed quantum flux densities of 0.73 nE/cm2 s of both colours, cycling was more rapid and peak-to-trough differences were smaller in red than in blue radiation. Blue radiation from below caused more rapid cycling with larger peak-to-trough differences than radiation from above. In red radiation the direction of radiation had a much smaller influence on period and peak-to-trough difference. To explain these qualitatively different effects of both colours on cycling stomata, the hypothesis is proposed that blue light increases the osmotic pressure in the guard cells more effectively than red light. In blue light the permeability for water transport of the guard cell membranes is lower than in red light. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Guard cells control hypocotyl elongation through HXK1, HY5, and PIF4

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Gilor Kelly ◽  
Danja Brandsma ◽  
Aiman Egbaria ◽  
Ofer Stein ◽  
Adi Doron-Faigenboim ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Blue Light ◽  
Opposite Effect ◽  
Red Light ◽  
Guard Cells ◽  
Cell Types ◽  
Hypocotyl Elongation ◽  
Sugar Production ◽  
Effect Of Light

AbstractThe hypocotyls of germinating seedlings elongate in a search for light to enable autotrophic sugar production. Upon exposure to light, photoreceptors that are activated by blue and red light halt elongation by preventing the degradation of the hypocotyl-elongation inhibitor HY5 and by inhibiting the activity of the elongation-promoting transcription factors PIFs. The question of how sugar affects hypocotyl elongation and which cell types stimulate and stop that elongation remains unresolved. We found that overexpression of a sugar sensor, Arabidopsis hexokinase 1 (HXK1), in guard cells promotes hypocotyl elongation under white and blue light through PIF4. Furthermore, expression of PIF4 in guard cells is sufficient to promote hypocotyl elongation in the light, while expression of HY5 in guard cells is sufficient to inhibit the elongation of the hy5 mutant and the elongation stimulated by HXK1. HY5 exits the guard cells and inhibits hypocotyl elongation, but is degraded in the dark. We also show that the inhibition of hypocotyl elongation by guard cells’ HY5 involves auto-activation of HY5 expression in other tissues. It appears that guard cells are capable of coordinating hypocotyl elongation and that sugar and HXK1 have the opposite effect of light on hypocotyl elongation, converging at PIF4.

scholarly journals Blue and red light effects on stomatal oscillations

2019 ◽  
Vol 46 (2) ◽  
pp. 146 ◽  
Author(s):  
Trevor Ballard ◽  
David Peak ◽  
Keith Mott
Keyword(s):  
Blue Light ◽  
Guard Cell ◽  
Red Light ◽  
Guard Cells ◽  
Surrounding Tissue ◽  
Single Pair ◽  
Fibre Optic ◽  
Fibre Optics ◽  
Cell Pair ◽  
Low Intensity

The response of stomata to red and blue light was investigated using small fibre optics (66µm diameter) to control light levels on a single pair of guard cells without affecting the surrounding tissue. Low intensity red light (50µmolm–2s–1) applied to the entire leaf caused stomata to oscillate continuously for several hours with no apparent decrease in amplitude with time. Adding low intensity blue light (50µmolm–2s–1) caused stomata to stop oscillating, but oscillations resumed when the blue light was removed. Adding the same intensity of red light to an oscillating leaf changed the amplitude of the oscillations but did not stop them. When blue light was added to a single guard cell pair (using a fibre optic) in a red-light-illuminated leaf, the stoma formed by that pair stopped oscillating, but adjacent stomata did not. Red light added to a single guard cell pair did not stop oscillations. Finally, blue light applied through a fibre optic to areas of leaf without stomata caused proximal stomata to stop oscillating, but distal stomata continued to oscillate. The data suggest that blue light affects stomata via direct effects on guard cells as well as by indirect effects on other cells in the leaf.

Smallseed Dodder (Cuscuta planiflora) Phototropism toward Far-red When in White Light

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Gregory L. Orr ◽  
Mustapha A. Haidar ◽  
Deborah A. Orr
Keyword(s):  
Blue Light ◽  
Potassium Iodide ◽  
White Light ◽  
Host Location ◽  
Red Light ◽  
Infra Red ◽  
Red Radiation

White light-grown seedlings of smallseed dodder were (a) provided with unilateral far-red (700 to 800 nm) at photon irradiances ranging from 20 to 110 μmol m−2s−1against a background of cool white light (400 to 700 nm) from above at 77 μmol m−2s−1, or (b) transferred to darkness and provided with unilateral white light at 20 μmol m−2s−1, unilateral blue light (400 to 500 nm) at 10 μmol m−2s−1, unilateral red light (600 to 700 nm) at 10 μmol m−2s−1, unilateral far-red at 50 μmol m−2s−1, or (c) in experiments utilizing bilateral irradiations, provided with unilateral far-red perpendicular to unilateral white light. Positive phototropic curvature was induced by unilateral white light and by unilateral blue light in otherwise darkness and by unilateral far-red in a background of cool white light. Seedling vines were also phototropic toward unilateral far-red when provided with unilateral white light perpendicular to unilateral far-red. Phototropism to unilateral white light was inhibited in seedlings treated with 200 μM norflurazon and 50 mM potassium iodide. Norflurazon- and potassium iodide-treated seedlings remained phototropic toward unilateral far-red when provided with unilateral white light perpendicular to unilateral far-red. Seedling vines were not phototropic to unilateral red or to unilateral far-red in otherwise darkness, and seedlings in cool white light were neither skototropic (i.e., tropic toward unilateral darkness) nor tropic to or from infra-red (radiation with wavelengths greater than 900 nm). Phototropism toward regions of lowered red:far-red may aid smallseed dodder in chlorophyllous host location and attachment.

scholarly journals State-of-the-art and prospects for intense red radiation from core–shell InGaN/GaN nanorods

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Evgenii A. Evropeitsev ◽  
Dmitrii R. Kazanov ◽  
Yoann Robin ◽  
Alexander N. Smirnov ◽  
Ilya A. Eliseyev ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Red Light ◽  
Cylindrical Part ◽  
Core Shell ◽  
Light Emitting ◽  
Color Displays ◽  
Blue Radiation ◽  
Photon States ◽  
White Light Emitting Diodes ◽  
Red Radiation

Abstract Core–shell nanorods (NRs) with InGaN/GaN quantum wells (QWs) are promising for monolithic white light-emitting diodes and multi-color displays. Such applications, however, are still a challenge because intensity of the red band is too weak compared with blue and green. To clarify this problem, we measured photoluminescence of different NRs, depending on power and temperature, as well as with time resolution. These studies have shown that dominant emission bands come from nonpolar and semipolar QWs, while a broad yellow-red band arises mainly from defects in the GaN core. An emission from polar QWs located at the NR tip is indistinguishable against the background of defect-related luminescence. Our calculations of electromagnetic field distribution inside the NRs show a low density of photon states at the tip, which additionally suppresses the radiation of polar QWs. We propose placing polar QWs inside a cylindrical part of the core, where the density of photon states is higher and the well area is much larger. Such a hybrid design, in which the excess of blue radiation from shell QWs is converted to red radiation in core wells, can help solve the urgent problem of red light for many applications of NRs.

scholarly journals Quantum Requirement for Photosynthesis in Chlorophyll-Deficient Plants with Unusual Lamellar Structures

1967 ◽  
Vol 50 (9) ◽  
pp. 2131-2144 ◽  
Author(s):  
Georg H. Schmid ◽  
Hans Gaffron
Keyword(s):  
Quantum Number ◽  
Blue Light ◽  
Lamellar Structure ◽  
Higher Plants ◽  
Red Light ◽  
Blue Region ◽  
Lamellar Structures ◽  
Quantum Requirement ◽  
Optimal Efficiency ◽  
Red Radiation

Neither an over-all deficiency of chlorophyll, nor an increased enzymatic capacity for maximal rates, nor an unusual lamellar structure was found to change the number of quanta required for the evolution of one molecule of oxygen in healthy aurea mutants of tobacco. The average minimal quantum number remains 10 (efficiency 0.1) as in many algae and typical higher plants. Most of the time the optimal efficiency depends on the availability of some far-red radiation, particularly in the blue region of the spectrum where blue light alone is rather inefficient. These results fit an explanation offered earlier in connection with the hydrogen or acetate photometabolism of algae in far-red light.

scholarly journals Phototropin 1 and dim-blue light modulate the red light de-etiolation response

2014 ◽  
Vol 9 (11) ◽  
pp. e976158
Author(s):  
Yihai Wang ◽  
Kevin M Folta
Keyword(s):  
Blue Light ◽  
Red Light

scholarly journals Single Wavelengths of LED Light Supplement Promote the Biosynthesis of Major Cyclic Monoterpenes in Japanese Mint

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1420
Author(s):  
Takahiro Ueda ◽  
Miki Murata ◽  
Ken Yokawa
Keyword(s):  
Blue Light ◽  
Solid Phase ◽  
Glandular Trichomes ◽  
Red Light ◽  
Glandular Trichome ◽  
Pulse Amplitude ◽  
Light Treatment ◽  
Led Light ◽  
Trichome Formation ◽  
Japanese Mint

Environmental light conditions influence the biosynthesis of monoterpenes in the mint plant. Cyclic terpenes, such as menthol, menthone, pulegone, and menthofuran, are major odor components synthesized in mint leaves. However, it is unclear how light for cultivation affects the contents of these compounds. Artificial lighting using light-emitting diodes (LEDs) for plant cultivation has the advantage of preferential wavelength control. Here, we monitored monoterpene contents in hydroponically cultivated Japanese mint leaves under blue, red, or far-red wavelengths of LED light supplements. Volatile cyclic monoterpenes, pulegone, menthone, menthol, and menthofuran were quantified using the head-space solid phase microextraction method. As a result, all light wavelengths promoted the biosynthesis of the compounds. Remarkably, two weeks of blue-light supplement increased all compounds: pulegone (362% increase compared to the control), menthofuran (285%), menthone (223%), and menthol (389%). Red light slightly promoted pulegone (256%), menthofuran (178%), and menthol (197%). Interestingly, the accumulation of menthone (229%) or menthofuran (339%) was observed with far-red light treatment. The quantification of glandular trichomes density revealed that no increase under light supplement was confirmed. Blue light treatment even suppressed the glandular trichome formation. No promotion of photosynthesis was observed by pulse-amplitude-modulation (PAM) fluorometry. The present result indicates that light supplements directly promoted the biosynthetic pathways of cyclic monoterpenes.

scholarly journals The Preferences of Different Cultivars of Lettuce Seedlings (Lactuca sativa L.) for the Spectral Composition of Light

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1211
Author(s):  
Barbara Frąszczak ◽  
Monika Kula-Maximenko
Keyword(s):  
Chlorophyll Content ◽  
Blue Light ◽  
White Light ◽  
Leaf Shape ◽  
Red Light ◽  
Spectral Composition ◽  
Fresh Weight ◽  
Light Spectrum ◽  
Dark Green ◽  
Relative Chlorophyll Content

The spectrum of light significantly influences the growth of plants cultivated in closed systems. Five lettuce cultivars with different leaf colours were grown under white light (W, 170 μmol m−2 s−1) and under white light with the addition of red (W + R) or blue light (W + B) (230 μmol m−2 s−1). The plants were grown until they reached the seedling phase (30 days). Each cultivar reacted differently to the light spectrum applied. The red-leaved cultivar exhibited the strongest plasticity in response to the spectrum. The blue light stimulated the growth of the leaf surface in all the plants. The red light negatively influenced the length of leaves in the cultivars, but it positively affected their number in red and dark-green lettuce. It also increased the relative chlorophyll content and fresh weight gain in the cultivars containing anthocyanins. When the cultivars were grown under white light, they had longer leaves and higher value of the leaf shape index. The light-green cultivars had a greater fresh weight. Both the addition of blue and red light significantly increased the relative chlorophyll content in the dark-green cultivar. The spectrum enhanced with blue light had positive influence on most of the parameters under analysis in butter lettuce cultivars. These cultivars were also characterised by the highest absorbance of blue light.

The Efficacy of Blue Light versus the Combination of Blue and Red Light Therapy in the Treatment of Acne Vulgaris

2021 ◽  
Author(s):  
Leila Kharazi ◽  
Sahar Dadkhahfar ◽  
Hoda Rahimi ◽  
Mehdi Gheisari ◽  
Nikoo Mozafari ◽  
...  
Keyword(s):  
Blue Light ◽  
Acne Vulgaris ◽  
Red Light ◽  
Light Therapy
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