scholarly journals Manipulation of Intraday Durations of Blue- and Red-Light Irradiation to Improve Cos Lettuce Growth

2021 ◽  
Vol 12 ◽  
Author(s):  
Tomohiro Jishi ◽  
Ryo Matsuda ◽  
Kazuhiro Fujiwara
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Dry Weight ◽  
Photosynthetic Photon Flux Density ◽  
Light Irradiation ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Leaf Elongation ◽  
Shoot Dry Weight ◽  
Lettuce Growth

The morphology of plants growing under combined blue- and red-light irradiation is affected by the presence or absence of time slots of blue- and red-light mono-irradiation. The purposes of this study were to investigate the morphology and growth of cos lettuce grown under light irradiation combining several durations of blue and red light simultaneously and independent mono-irradiations of blue and red light during the day, and to clarify the effects of the durations of blue-light mono-irradiation and blue-light irradiation. Young cos lettuce seedlings were grown under 24-h blue-light irradiation with a photosynthetic photon flux density (PPFD) of 110μmol m−2 s−1 (B+0R) or under 24-h blue-light irradiation with a PPFD of 100μmol m−2 s−1 supplemented with 8 (B+8R), 16 (B+16R), and 24-h (B+24R) red-light irradiation with PPFDs of 30, 15, and 10μmol m−2 s−1, respectively (Experiment 1). The daily light integral was 9.50mol m−2 in all treatments. In Experiment 1, leaf elongation was promoted as the duration of red-light irradiation decreased and the duration of blue-light mono-irradiation increased. The maximum shoot dry weight was observed under the B+8R treatment. Growth was likely promoted by the expansion of the light-receptive area caused by moderate leaf elongation without tilting. In Experiment 2, young cos lettuce seedlings were grown as for Experiment 1, but blue- and red-light irradiation intensities were reversed (R+0B, R+8B, R+16B, and R+24B). Leaf elongation was promoted by the absence of blue-light irradiation (R+0B). The leaf surface was increasingly flattened, and the shoot dry weight was enhanced, as the duration of blue-light irradiation increased. Thus, cos lettuce leaf morphology may be manipulated by adjusting each duration of blue-light mono-irradiation, red-light mono-irradiation, and blue- and red-light simultaneous irradiation, which can, in turn, promote cos lettuce growth.

scholarly journals Blue Light Monochromatic Irradiation for 12 Hours in Lighting Pattern with Combinations of Blue and Red Light Elongates Young Cos Lettuce Leaves and Promotes Growth under High Daily Light Integral

HortScience ◽  
2021 ◽  
pp. 1-6
Author(s):  
Tomohiro Jishi ◽  
Ryo Matsuda ◽  
Kazuhiro Fujiwara
Keyword(s):  
Flux Density ◽  
Blue Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Dry Weight ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Leaf Elongation

Cos lettuce was grown under different spectral photon flux density distribution (SPFD) change patterns with blue- and/or red light-emitting diode (LED) irradiation with a 24-hour cycle. Twelve treatments were designed with a combination of four relative SPFD (RSPFD) change patterns and three photosynthetic photon flux density (PPFD) levels. The RSPFD change patterns were as follows: BR/BR, simultaneous blue- and red-light irradiation (BR) for 24 h; R/BR, red-light monochromatic irradiation (R) for 12 h followed by 12 hours of BR; B/BR, blue-light monochromatic irradiation (B) for 12 hours followed by 12 hours of BR; and B/R, 12 hours of B followed by 12 hours of R. Each RSPFD change pattern was conducted at three daily average photosynthetic photon flux densities (PPFDave) of 50, 100, and 200 µmol·m−2·s−1. The RSPFD change patterns that included B (B/BR and B/R) resulted in elongated leaves. A low ratio of active phytochrome to total phytochrome under B was considered the reason for leaf elongation. Shoot dry weight was significantly greater under the RSPFD change patterns that included B when the PPFDave was 200 µmol·m−2·s−1. The leaf elongation caused by B would have increased the amount of light received and thereby promoted growth. However, excessive leaf elongation caused the plants to fall, and growth was not promoted under the RSPFD change patterns that included B when the PPFDave was 50 µmol·m−2·s−1. Thus, 12-hour B promoted growth under conditions in which leaf elongation leads to increases in the amount of light received.

scholarly journals Application of an Automatic Control System of Photosynthetic Photon Flux Density for LED-Low Light Irradiation Storage of Green Plants

2005 ◽  
Vol 15 (4) ◽  
pp. 781-786 ◽  
Author(s):  
Kazuhiro Fujiwara ◽  
Toshinari Sawada ◽  
Yoshikatsu Kimura ◽  
Kenji Kurata
Keyword(s):  
Flux Density ◽  
Blue Light ◽  
Red Light ◽  
Dry Weight ◽  
Photosynthetic Photon Flux Density ◽  
Light Irradiation ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Low Light

A light-emitting diode (LED)-low light irradiation (LLI) storage system was developed for suppressing the change in dry weight and maintaining the quality of green plants during long-term storage. In this system, the carbon dioxide (CO2) exchange rate was maintained at zero by automatically adjusting the photosynthetic photon flux density (PPFD) with a proportional-integralderivative (PID) controller. The voltage supplied to the LEDs was controlled by the difference between the inflow (400 μmol·mol-1) and outflow CO2 concentrations in the storage case. Grafted tomato (Lycopersicon esculentum; scion = `House Momotaro'; rootstock = `Anchor T') plug seedlings were stored at 10 °C for 35 days under four different LLI conditions as a system operating test: fixed red light irradiation at 2 μmol·m-2·s-1, PID-controlled red light irradiation with no blue light, and PID-controlled red light irradiation with blue light at 0.2 or 1.0 μmol·m-2·s-1. The results showed that the automatic PPFD control during LED-LLI helped suppress changes in dry weight during storage as expected. Furthermore, it was found that addition of a low percentage of blue light improved the morphological appearance of the seedlings and reduced the PPFD required to suppress the change in dry weight.

scholarly journals Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms

2021 ◽  
Vol 12 ◽  
Author(s):  
Jun Liu ◽  
Marc W. van Iersel
Keyword(s):  
Blue Light ◽  
Interactive Effect ◽  
Red Light ◽  
Green Light ◽  
Photosynthetic Photon Flux Density ◽  
Interactive Effects ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Spectrum ◽  
Response Curves

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than green light, because green light is absorbed less efficiently. However, because of its lower absorptance, green light can penetrate deeper and excite chlorophyll deeper in leaves. We hypothesized that, at high photosynthetic photon flux density (PPFD), green light may achieve higher QY and net CO2 assimilation rate (An) than red or blue light, because of its more uniform absorption throughtout leaves. To test the interactive effects of PPFD and light spectrum on photosynthesis, we measured leaf An of “Green Tower” lettuce (Lactuca sativa) under red, blue, and green light, and combinations of those at PPFDs from 30 to 1,300 μmol⋅m–2⋅s–1. The electron transport rates (J) and the maximum Rubisco carboxylation rate (Vc,max) at low (200 μmol⋅m–2⋅s–1) and high PPFD (1,000 μmol⋅m–2⋅s–1) were estimated from photosynthetic CO2 response curves. Both QYm,inc (maximum QY on incident PPFD basis) and J at low PPFD were higher under red light than under blue and green light. Factoring in light absorption, QYm,abs (the maximum QY on absorbed PPFD basis) under green and red light were both higher than under blue light, indicating that the low QYm,inc under green light was due to lower absorptance, while absorbed blue photons were used inherently least efficiently. At high PPFD, the QYinc [gross CO2 assimilation (Ag)/incident PPFD] and J under red and green light were similar, and higher than under blue light, confirming our hypothesis. Vc,max may not limit photosynthesis at a PPFD of 200 μmol m–2 s–1 and was largely unaffected by light spectrum at 1,000 μmol⋅m–2⋅s–1. Ag and J under different spectra were positively correlated, suggesting that the interactive effect between light spectrum and PPFD on photosynthesis was due to effects on J. No interaction between the three colors of light was detected. In summary, at low PPFD, green light had the lowest photosynthetic efficiency because of its low absorptance. Contrary, at high PPFD, QYinc under green light was among the highest, likely resulting from more uniform distribution of green light in leaves.

The value of red light at night for increasing basil yield

2018 ◽  
Vol 98 (6) ◽  
pp. 1321-1330
Author(s):  
Jaimin S. Patel ◽  
Leora Radetsky ◽  
Mark S. Rea
Keyword(s):  
Plant Height ◽  
Red Light ◽  
Leaf Size ◽  
Cost Effective ◽  
Dry Weight ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light At Night ◽  
Sweet Basil

Sweet basil (Ocimum basilicum L.) is primarily used for culinary purposes, but it is also used in the fragrance and medicinal industries. In the last few years, global sweet basil production has been significantly impacted by downy mildew caused by Peronospora belbahrii Thines. Nighttime exposure to red light has been shown to inhibit sporulation of P. belbahrii. The objective of this study was to determine if nighttime exposure to red light from light-emitting diodes (λmax = 625 nm) could increase plant growth (plant height and leaf size) and yield (number and weight of leaves) in basil plants. In two sets of greenhouse experiments, red light was applied at a photosynthetic photon flux density of 60 μmol m−2 s−1 during the otherwise dark night for 10 h (from 2000 to 0600). The results demonstrate that exposure to red light at night can increase the number of basil leaves per plant, plant height, leaf size (length and width), and leaf fresh and dry weight compared with plants in darkness at night. The addition of incremental red light at night has the potential to be cost-effective for fresh organic basil production in controlled environments.

scholarly journals Optimal LED Wavelength Composition for the Production of High-Quality Watermelon and Interspecific Squash Seedlings Used for Grafting

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 870 ◽  
Author(s):  
Filippos Bantis ◽  
Athanasios Koukounaras ◽  
Anastasios S. Siomos ◽  
Kalliopi Radoglou ◽  
Christodoulos Dangitsis
Keyword(s):  
Blue Emission ◽  
Dry Weight ◽  
Photosynthetic Photon Flux Density ◽  
Stem Diameter ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Sources ◽  
High Quality ◽  
Light Emitting ◽  
Shoot Dry Weight

Watermelon is cultivated worldwide and is mainly grafted onto interspecific squash rootstocks. Light-emitting diodes (LEDs) can be implemented as light sources during indoor production of both species and their spectral quality is of great importance. The objective of the present study was to determine the optimal emission of LEDs with wide wavelength for the production of watermelon and interspecific squash seedlings in a growth chamber. Conditions were set at 22/20 °C temperature (day/night), 16 h photoperiod, and 85 ± 5 μmol m−2 s−1 photosynthetic photon flux density. Illumination was provided by fluorescent (FL, T0) lamps or four LEDs (T1, T2, T3, and T4) emitting varying wide spectra. Watermelon seedlings had greater shoot length, stem diameter, cotyledon area, shoot dry weight-to-length (DW/L) ratio, and Dickson’s quality index (DQI) under T1 and T3, while leaf area and shoot dry weight (DW) had higher values under T1. Interspecific squash seedlings had greater stem diameter, and shoot and root DW under T1 and T3, while leaf and cotyledon areas were favored under T1. In both species, T0 showed inferior development. It could be concluded that a light source with high red emission, relatively low blue emission, and a red:far-red ratio of about 3 units seems ideal for the production of high-quality watermelon (scion) and interspecific squash (rootstock) seedlings.

scholarly journals Sunlight transmitted by colored shade nets on photosynthesis and yield of cucumber

2018 ◽  
Vol 48 (9) ◽  
Author(s):  
Felipe Ayala Tafoya ◽  
Moisés Gilberto Yáñez Juárez ◽  
Carlos Alfonso López Orona ◽  
Raymundo Medina López ◽  
Teresa de Jesús Velázquez Alcaraz ◽  
...  
Keyword(s):  
Block Design ◽  
Red Light ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Protected Cultivation ◽  
Photosynthetic Responses ◽  
Photosynthetic Properties

ABSTRACT: Black shading nets are widely used in the protected cultivation of vegetables as a technique for controlling light and temperature, while the colored shading nets, with special optical properties to improve the use of solar radiation, appeared recently in the agricultural plastics market. Light quality transmitted by gray, aluminized, pearl, blue, red and black (control) nets with 30% shade was evaluated, as well as its effects on photosynthetic properties and fruits production of cucumber plants. Treatments (shade nets) were established under a randomized complete block design with four repetitions. The red net transmitted 23.7 and 40.3% more photosynthetic photon flux density (400 to 700nm) and red light (600 to 700nm) and the blue net transmitted 36% more blue light (400 to 500nm) in comparison with the respective transmissions of black net. All nets increased the photosynthetic responses: transpiration, stomatal conductance and CO2 assimilation, observed in plants grown under black net. Leaf greenness (41.6 SPAD units) and foliar area (90dm2) increased 22.8 and 38.9% with the red net, while the dry weight of leaf (52.5g) increased 21.9% with pearl net. Pearl, red, aluminized and blue nets showed to be viable alternatives because the production of fruit increased in 71, 48, 46 and 46%, respectively, in comparison with the conventional black net (52t ha-1).

scholarly journals Effects of Blue and Red Light On Growth And Nitrate Metabolism In Pakchoi

2019 ◽  
Vol 17 (1) ◽  
pp. 456-464
Author(s):  
Xiao-Xue Fan ◽  
Feng Xue ◽  
Bo Song ◽  
Long-Zheng Chen ◽  
Gang Xu ◽  
...  
Keyword(s):  
Blue Light ◽  
White Light ◽  
Red Light ◽  
Glutamate Synthase ◽  
Photosynthetic Photon Flux Density ◽  
Continuous Illumination ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Key Enzymes ◽  
Chlorophyll Contents

AbstractThis study investigated the effects of blue and red light on metabolites of nitrate, key enzymes, and the gene expression of key enzymes in pakchoi plants (Brassica campestris L. var. Suzhouqing). Plants were grown under three light quality treatments, namely, white light (W), red light (R) and blue light (B), at the same photosynthetic photon flux density (PPFD) of approximately 150 μmol m-2 s-1 for 48 hours of continuous illumination, and W was set as the control. The dynamics of net photosynthetic rate in pakchoi subjected to different light treatments were the same as the total chlorophyll contents: blue light > white light > red light. The nitrate reductase (NR) activity, nitrite reductase (NiR) activity, glutamine synthetase (GS) activity and glutamate synthase (GOGAT) activity were highest under blue light. Further, the expression levels of NR, NiR and GS genes were significantly higher under blue light. Under continuous illumination, the auxin content (IAA) in pakchoi leaves was highest under blue light, whereas the abscisic acid (ABA) content was highest under red light. In contrast, there was no significant effect for gibberellin (GA) under any type of light treatment.

scholarly journals Spectral Transmittance of Selected Greenhouse Construction and Nursery Shading Material

1990 ◽  
Vol 8 (3) ◽  
pp. 118-121 ◽  
Author(s):  
M.J. McMahon ◽  
J.W. Kelly ◽  
D.R. Decoteau
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Construction Materials ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Spectral Transmittance ◽  
Radiation Transmission ◽  
Solar Noon

Abstract Spectral transmittance properties of several greenhouse construction and shading materials were determined by measuring the quantity and quality of solar radiation transmission on non-clouded (sunny) days at solar noon. Spectral transmittance parameters included photosynthetic radiation (400–700 nm) and photomorphogenic radiation (660 nm (red light), 730 nm (far-red light), and 400–500 nm (blue light). Light available for photosynthesis was measured as photosynthetic photon flux density (PPFD) and photosynthetic radiation (PI). Photomorphogenic radiation was measured as far-red/red (FR/R) and blue light. Greenhouse construction materials included glass, chambered acrylic, chambered polycarbonate, and inflated plastic film. Various shade materials of different colors were evaluated. Photosynthetically active radiation transmission of construction materials ranged from approximately 95% transmission of direct sunlight with Exolite to less than 50% with tinted Lexan. Far-red/red values of shade materials ranged from 0.94 for Enduro Green to 5.58 for Cravo LS-7.

scholarly journals Blue versus Red Light Can Promote Elongation Growth Independent of Photoperiod: A Study in Four Brassica Microgreens Species

HortScience ◽  
2019 ◽  
Vol 54 (11) ◽  
pp. 1955-1961 ◽  
Author(s):  
Yun Kong ◽  
Devdutt Kamath ◽  
Youbin Zheng
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Photosynthetic Photon Flux Density ◽  
Elongation Growth ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Extension Rate ◽  
Hypocotyl Length ◽  
Led Lighting

An elongated stem has beneficial effects on microgreen production. Previous studies indicate that under 24-hour light-emitting diode (LED) lighting, monochromatic blue light, compared with red light, can promote plant elongation for some species. The objective of this study was to investigate whether shortened photoperiod can change blue vs. red light effects on elongation growth. The growth and morphology traits of arugula (Brassica eruca, ‘Rocket’), cabbage (Brassica oleracea, unknown variety name), mustard (Brassica juncea, ‘Ruby Streaks’), and kale (Brassica napus, ‘Red Russian’) seedlings were compared during the stage from seeding to cotyledon unfolding under two light quality × two photoperiod treatments: 1) R, monochromatic red light (665 nm) and 2) B, monochromatic blue light (440 nm) using continuous (24-hour light/0-hour dark) or periodic (16-hour light/8-hour dark) LED lighting. A photosynthetic photon flux density of ≈100 μmol·m−2·s−1 and an air temperature of ≈22 °C was used for the preceding treatments. After 7 to 8 days of lighting treatment, regardless of photoperiod, B promoted elongation growth compared with R, as demonstrated by a greater stem extension rate, hypocotyl length, or petiole length in the tested microgreen species, except for mustard. The promotion effects on elongation were greater under 24- vs. 16-hour lighting in many cases. Among the tested species, mustard showed the lowest sensitivity in elongation response to B vs. R, which was independent of photoperiod. This suggests that the blue-light-promoted elongation is not specifically from 24-hour lighting, despite the varying promotion degree under different photoperiods or for different species. The elongation growth promoted by blue LED light under a photoperiod of either 24 hours or 16 hours can potentially benefit indoor production of microgreens.

scholarly journals Effect of Pre-Harvest Supplemental UV-A/Blue and Red/Blue LED Lighting on Lettuce Growth and Nutritional Quality

Horticulturae ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 80
Author(s):  
Triston Hooks ◽  
Joseph Masabni ◽  
Ling Sun ◽  
Genhua Niu
Keyword(s):  
Blue Light ◽  
Nutritional Quality ◽  
Uv Light ◽  
Ultra Violet ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Daily Light Integral ◽  
Lettuce Growth ◽  
Supplemental Lighting

Blue light and ultra-violet (UV) light have been shown to influence plant growth, morphology, and quality. In this study, we investigated the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on growth and nutritional quality of lettuce grown hydroponically in two greenhouse experiments. The RB spectrum was applied pre-harvest for two days or nights, while the UV-A/Blue spectrum was applied pre-harvest for two or four days or nights. All pre-harvest supplemental lighting treatments had a same duration of 12 h with a photon flux density (PFD) of 171 μmol m−2 s−1. Results of both experiments showed that pre-harvest supplemental lighting using UV A/Blue or RB light can increase the growth and nutritional quality of lettuce grown hydroponically. The enhancement of lettuce growth and nutritional quality by the pre-harvest supplemental lighting was more effective under low daily light integral (DLI) compared to a high DLI and tended to be more effective when applied during the night, regardless of spectrum.

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