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Green-light supplementation for enhanced lettuce growth under red- and blue-light-emitting diodes
... Bantis et al. (2016) showed that the treatments with high red:far-red ratio induced the lowest growth rate resulting in the formation of the shortest shoots of two sweet basil cultivars (Ocimum basilicum). The greatest growth of the shoots under blue and red LEDs light compared to white fluorescent light has been reported for different vegetable species such as lettuce (KIM et al., 2004; JOHKAN et al., 2010; LIN et al., 2013), pepper (SCHUERGER et al., 1997), cucumber (BRAZAITYTE et al., 2009), tomato (BRAZAITYTE et al., 2010), and rapeseed (LI et al., 2013). Root collar diameter of the lettuce and sweet pepper seedlings were significantly greater under blue and red LEDs light compared to the CWF light, while cucumber seedlings showed no significant differences (Figure 1C). ...
... Root length of cucumber was increased at 41% under blue and red LEDs lighting compared to the CWF lighting (Figure 1D). Positive response in the root growth of plants grown under blue and red LED light compared to the white fluorescent light has been reported in lettuce (KIM et al., 2004; JOHKAN et al., 2010), pepper (SCHUERGER et al., 1997), and sweet basil (BANTIS et al., 2016). However, Lin et al. (2013reported that lighting with blue and red LEDs and white fluorescent light did not influence the growth of lettuce roots, at 35 days after sowing. ...
... Yorio et al. (2001) reported that there was higher SDM accumulation in lettuce grown under blue and red LEDs light than in lettuce grown under red LEDs light alone. Kim et al. (2004) showed that when photosynthetic photon flux density (PPFD) is kept constant, the lettuce grown in a combination of red, blue, and green LED light had larger leaf area and higher SDM than those grown exclusively under red or blue alone. According to the authors the interpretation for this result is that although red and blue light are more effective for promoting photosynthesis, green light might penetrate plant leaves more efficiently and increase carbon fixation (KIM et al., 2004; TERASHIMA et al., 2009). ...
The response of lettuce (Lactuca sativa), cucumber (Cucumis sativus) and sweet pepper (Capsicum annuum) seedlings to light spectral quality when grown under continuous illumination was investigated in relation to the growth, dry matter, and seedling quality index. Different light quality treatments were applied during the germination and plant growth steps, using cool-white fluorescent bulbs (CWF) or red and blue light-emitting diodes (LEDs) at an fluence of 30 and 25 μmol m-2 s-1 photosynthetic photon flux density (PPFD), respectively. Treatments were arranged in a completely randomized design in a 3×2 factorial: three vegetable species (lettuce, cucumber and sweet pepper) and two light quality treatments (white fluorescent light or red and blue LEDs), with four replications. Results showed that the vegetables had distinct growth responses to different light-quality treatments. Number of leaves was significantly greater under blue and red LEDs light compared to the CWF lighting, for the three vegetable species. Shoot length and root collar diameter of lettuce and sweet pepper were significantly greater under blue and red LEDs light compared to the CWF light, while cucumber seedlings showed no significant differences. Root length, root dry matter and Dickson quality index (DQI) of the cucumber seedlings was significantly greater under blue and red LEDs light compared to the CWF light, while lettuce and sweet pepper seedlings showed no significant differences. Shoot dry matter (SDM) and total dry matter (TDM) of the lettuce and cucumber seedlings were greater when grown under blue and red LEDs light. The lighting with blue and red wavelengths from LEDs resulted in better quality cucumber seedlings compared to the cool-white fluorescent light. The shoot growth rate of lettuce seedlings was favored by blue and red LEDs light. Different spectral qualities have little effect on growth and development of sweet pepper seedlings.
... Red to far-red light (λ e ≈ 630-750 nm) is known to cause high growth rates and smaller cells [19,46,49,[67][68][69] by accelerating the cell cycle in many microalgae of diverse evolutionary lines. However, far-red light can suppress volumetric biomass production when supplemented to a broadband light source [69], as it regulates light harvesting mechanisms in microalgae [68]. ...
... Higher lipid content in biomass when compared to red (650-680 nm) LED. [49] 500 Chlorella sp. Blue light induces slightly higher lipid production compared to red light. ...
... Conversely, light sources with high red light content (e.g. in HRLB, FL, LED 660) promote higher cell count-based growth (P cell , µ cell and X cell ), most probably because red light induces an acceleration of the cell cycle, being accompanied by decreased cell size and weight as found in the present study and elsewhere [19,46,49,[67][68][69]. This effect may also need to be considered for harvesting procedures, as smaller cells might be more difficult to flocculate or centrifuge than larger cells, increasing production costs and decreasing the overall energy efficiency of the process. ...
Light-emitting diodes (LEDs) will become one of the world´s most important light sources and their integration in microalgal production systems (photobioreactors) needs to be considered. Microalgae need a balanced mix of wavelengths for normal growth, responding to light differently according to the pigments acquired or lost during their evolutionary history. In the present study, Nannochloropsis oculata and Tetraselmis chuii were exposed to different light qualities, and their effects on growth, biochemical components (carbohydrate, protein, total lipid and fatty acids) and morphologic traits (cell shape, size, growth phase, absorption spectrum, N-P-C elemental composition in biomass) were investigated. An additional experiment employed different LEDs in order to obtain di- and multichromatic tailored light to increase biomass production. Both N. oculata and T. chuii showed a higher maximal volumetric ash free dry weight content in the culture when exposed to blue (465 nm) and red (660 nm) light, respectively. However, balanced light quality, provided via fluorescent light (FL) and dichromatic blue and red light treatment, was found to be beneficial for biomass growth rates of both algae. Significant changes in the biochemical composition were observed among treatments. Furthermore, algae treated with monochromatic blue light (λe = 405 and 465 nm) often displayed higher nutrient uptake and different morphological traits as compared to algae exposed to red light (λe = 630 and 660 nm). It is suggested that differential response to light quality is partially influenced by observed changes in nutrient consumption and biomass productivity. In terms of biomass per input energy, the most efficient light sources were those with photon output peaks at 660 nm (e.g. LED 660 and FL for plant growth). Research and the application of LED technology to microalgal production is often hindered by inadequate light quantity measurements as well as by inadequate LED manufacture and engineering, leading to the use of inefficient LED modules, which, in turn, may affect microalgal growth and biochemistry.
... Higher G intensity also increased the content of photosynthetic pigments in Arabidopsis seedlings, and biomass and photosynthetic parameters in leaves of lettuce (Efimova et al. 2013;Golovatskaya & Karnachuk 2008;Johkan et al. 2012;Muneer et al. 2014). Lettuce plants grown in a mixture of R, B and G (RBG) had larger specific leaf area (SLA) but lower stomatal conductance compared with RB alone, where the total light intensity of RBG was higher than that of RB (Kim 2005). Plant height and dry weight increased in cucumbers when adding 520 nm G to a mixture of B, R and far-red light (RBFrG) compared with RBFr alone of similar light intensity, whereas such effects were not found when adding 595 nm G (Brazaitytė et al. 2009). ...
... Partially replacing sole R or B or R/B mixture by green light did not cause differences in leaf area, SLA, shoot: root ratio and biomass of MM and cry1a mutant. This contradicts previous findings on green light responses, but in those studies PPFD also increased when adding G(Kim 2005;Novičkovas et al. 2012;Samuolienė et al. 2012). Zhang et al. (2011 reported that 40% green light induced a shade avoidance response in Arabidopsis seedlings, whereas 10% did not. ...
Although green light is sometimes neglected, it can have several effects on plant growth and development. Green light is probably sensed by cryptochromes (crys), one of the blue light photoreceptor families. The aim of this study is to investigate the possible interaction between green and blue light and the involvement of crys in the green light response of plant photomorphogenesis. We hypothesize that green light effects on morphology only occur when crys are activated by the presence of blue light. Wild‐type Moneymaker (MM), cry1a mutant (cry1a) and two CRY2 overexpressing transgenic lines (CRY2‐OX3 and CRY2‐OX8) of tomato (Solanum lycopersicum) were grown in a climate chamber without or with green light (30 μmol m‐2 s‐1) on backgrounds of sole red, sole blue and red/blue mixture, with all treatments having the same photosynthetic photon flux density of 150 μmol m‐2 s‐1. Green light showed no significant effects on biomass accumulation, nor on leaf characteristics such as leaf area, specific leaf area, and chlorophyll content. However, in all genotypes, green light significantly decreased stem length on a sole blue background, whereas green light hardly affected stem length on sole red and red/blue mixture background. MM, cry1a and CRY2‐OX3/8 plants all exhibited similar responses of stem elongation to green light, indicating that cry1a, and probably cry2, is not involved in this green light effect. We conclude that partially replacing blue light by green light reduces elongation and that this is independent of cry1a.
... Higher G intensity also increased contents of photosynthetic pigments in Arabidopsis seedlings, and biomass and photosynthetic parameters in leaves of lettuce (Golovatskaya and Karnachuk, 2008;E mova et al., 2013;Johkan et al., 2012;Muneer et al., 2014). Lettuce plants grown in a mixture of R, B and G (RBG) had larger speci c leaf area (SLA) but lower stomatal conductance (gs) compared with RB alone, where the total light intensity of RBG was higher than that of RB (Kim, 2005). ...
... 9).Partially replacing sole R or B or R/B mixture by green light did not cause differences in leaf area, SLA, shoot: root ratio and biomass of MM and cry1a mutant. This contradicts previous ndings on green light responses, but in those studies PPFD also increased when adding G(Kim, 2005; Samuolienė et al., 2012; Novičkovas at al., 2012). Zhang et al. (2011 ...
Although green light is often neglected it can have several effects on plant growth and development. Green light is probably sensed by cryptochromes (crys), one of the blue light photoreceptor families. The aim of this study is to investigate the possible interaction between green and blue light and the involvement of crys in the green light response of plant photomorphogenesis. We hypothesize that green light effects on morphology only occur when crys are activated by the presence of blue light. Wild-type Moneymaker ( MM ), cry1a mutant ( cry1a ) and two CRY2 overexpressing transgenic lines ( CRY2-OX3 and CRY2-OX8 ) of tomato ( Solanum lycopersicum ) were grown in a climate chamber without or with green light (30 µmol m − 2 s − 1 ) on backgrounds of sole red, sole blue and red/blue mixture, with all treatments having the same photosynthetic photon flux density of 150 µmol m − 2 s − 1 . Green light showed no significant effect on biomass accumulation, nor on leaf photosynthesis and leaf characteristics such as leaf area, specific leaf area, and chlorophyll content. However, in all genotypes, green light significantly decreased stem length on a sole blue background, whereas green light did not affect stem length on sole red and red/blue mixture background. MM , cry1a and CRY2-OX3/8 plants all exhibited similar responses of stem elongation to green light, indicating that cry1a, and probably cry2, is not involved in this green light effect. We conclude that partially replacing blue light by green light reduces elongation and that this is independent of cry1a.
... The passive response can reflect resource limitation, whereas the active response changes allocation to offset loss in fitness in environment (Nicotra et al., 2010). Meanwhile, the response of morphological parameters to different light intensities revealed that the light regulates the structure of plants by signals from the environment (Hoenecke et al., 1992;Franklin et al., 2005;Kim et al., 2007). ...
... Compared with L3.5, additional green light may promote plant growth. Kim et al. [27] added green light to the red-blue LED to treat lettuce, and found that the dry weight of the shoot was greater than that of the red plus blue treatment, because the leaves in the lower canopy could use the transmitted green light for photosynthesis. ...
... Green light (500−600 nm) is commonly thought to be less effective in plants as most plants reflect green light. However, several studies reported that the addition of green light in combination with red and blue LEDs enhanced plant growth, since leaves in the lower layer of the canopy would be able to use the transmitted green light in photosynthesis (Klein 1992;Smith 1993;Kim 2004). Terashima et al. (2009) reported that green light can be absorbed by the lower layer of chloroplasts and drive leaf photosynthesis more efficiently than red light when sunflower was irradiated by strong white light. ...
... Plants grown under BR light had an average leaf area of 79.54 cm 2 which is smaller compared to plants grown in white light, where average leaf area was 100.03 cm 2 (Figure 1) . Many studies show different light quality compared to white light have inhibiting effects on plants and their growth as in the case with pepper, lettuce and tobacco (Brown et al. 1995, Kim 2004, Yang et al., 2016. As Choi et al. (2016) examined effects of LED with different wavelengths on the length of petioles and width of leaflets on strawberry plants they found out that combined illumination with red and blue LED light was the most effective in increasing the length of petioles as well as the width of leaflets. ...
The aim of this study was to investigate the effect of red (600-700 nm, peak 660), blue (400-500 nm, peak 450) and white light on the morphological and photosynthetic qualities of Cannabis sativa L. The two treatments were the white light (WL), and a combination of blue red lights (BR). Plants grown under WL were 23% taller than those grown under the BR light emitting diodes. The leaf area was also greater under WL than BR by 20%. The number of lateral branches and length of dominant lateral branch weren´t significantly different. It was concluded WL that emit a full spectrum of light affects plant growth and development better than BR light. The quantum efficiency ranged from 0.81 to 0.845 indicating the plants were not in stress.
... Light serves as an external factor to regulate the growth and development of in vitro plants. The broad spectrum of fluorescent lamps with a wavelength range from 380-750 nm are used as a light source for tissue culture (Kim et al., 2004). Light intensity and type of light affect date palm micropropagation (Al-Mayahi, 2016;Meziani et al., 2015). ...
Date palm (Phoenix dactylifera L.) is a fruit tree resilient to adverse climatic conditions predominating in hot arid regions of the Middle East and North Africa. The date fruit contains numerous chemical components that possess high nutritional and medicinal values. Traditional propagation by offshoots is inefficient to satisfy current demands for date palm trees. Alternatively, micropropagation provides an efficient means for large-scale propagation of date palm cultivars. Both somatic embryogenesis and organogenesis, either directly or indirectly though the callus phase, have been demonstrated in date palm in vitro regeneration. Culture initiation commonly utilizes shoot-tip explants isolated from young offshoots. Recently, the immature inflorescences of adult trees were utilized as an alternative nondestructive source of explants. In addition to the nature of the explant used, successful plant regeneration depends on the cultivar, composition of the culture medium and physical status. Challenges of date palm micropropagation include long in vitro cycle, latent contamination, browning, somaclonal variation as well as ex vitro acclimatization and transplanting. A remarkable amount of research investigating these factors has led to optimized protocols for the micropropagation of numerous commercially important cultivars. This has encouraged the development of several international commercial tissue culture laboratories. Molecular characterization provides an assurance of genetic conformity of regenerated plantlets, a key feature for commercial production. This article describes date palm micropropagation protocols and also discusses recent achievements with respect to somaclonal variation, molecular markers, cryopreservation and future prospects.
Index terms:
Cryopreservation; somatic embryogenesis; somaclonal variation; organogenesis; molecular marker.
... Lastly, increased green light content within a broadband light source can increase leaf photosynthesis and biomass production in land plants [3,49,50] because these photons can penetrate through the canopy and promote photosynthesis in leaves located below [12,16,51]. Mohsenpour and Willoughby demonstrated that green light could induce pigmentation in algae [51]. ...
Light-emitting diodes (LEDs) will become one of the
world’s most important light sources and their integration
in microalgal production systems (photobioreactors)
needs to be considered. LEDs can improve the
quality and quantity of microalgal biomass when applied
during specific growth phases. However, microalgae
need a balanced mix of wavelengths for normal growth,
and respond to light differently according to the pigments
acquired or lost during their evolutionary history.
This review highlights recently published results on the
effect of LEDs on microalgal physiology and biochemistry
and how this knowledge can be applied in selecting
different LEDs with specific technical properties for regulating
biomass production by microalgae belonging to
diverse taxonomic groups
... Green light (500−600 nm) is commonly thought to be less effective in plants as most plants reflect green light. However, several studies reported that the addition of green light in combination with red and blue LEDs enhanced plant growth, since leaves in the lower layer of the canopy would be able to use the transmitted green light in photosynthesis (Klein 1992;Smith 1993;Kim 2004). Terashima et al. (2009) reported that green light can be absorbed by the lower layer of chloroplasts and drive leaf photosynthesis more efficiently than red light when sunflower was irradiated by strong white light. ...
This chapter describes various types of plant factories, as well as various new plant management styles and technologies, are summarized.
... The combined effect of BL, RL, and 24% of GL caused the strongest growth of the L. sativa plant. The growth of leaf area and dry mass decreased with increase in the proportion of GL from 24 to 86% in the total luminous flux [18]. ...
Green light, along with other portions of the visible region of electromagnetic radiation, brings plants environmental information. Green light is a factor regulating the morphology of cells, tissues, and organs; photosynthesis; respiration and growth; and duration of stages of plant ontogenesis. This review summarizes the impact of the green light on the life of plants, and green light receptors and the mechanisms of its action are discussed.
... The structure of plants is regulated, in part, by light signals from the environment (Hoenecke et al., 1992;Franklin et al., 2005;Kim et al., 2007). Light is the energy source for photosynthetic organisms, and light intensity plays an important role in Different letters in columns indicate statistically significant differences (P < 0.05). ...
... The combination of red and blue LEDs has proven to be an effective lighting source for several crops (Kim et al., 2005). The addition of 24% green light (500-600 nm) to red and blue LEDs enhanced the growth of lettuce plants compared with plants grown under cool white fluorescent lamps (Kim, 2007). LED is characterized by high potential efficiency in converting electrical power into radiant power, robustness, long life expectancy, small size and directional light emission. ...
Recent research using Arabidopsis has shown that blue light stimulates the plant through the receptor
protein and induces regulations physiologically and morphologically. It is important to know whether the
theory can be used in food crop production. In the present study blue light emitted from light-emitting
diodes (LED) was used as a stimulus to tomato crop canopy after sunset for 2 h to induce xerophytophysiological
regulations. Blue (450 nm), white and red (660 nm) LED lamps, all with a properties of 0.48 W,
24 V, and 45 �mol m2 s−1 at 10 cm over the lamp, were compared with non-illumination control. A 2
×
4
two factor experiment was conducted in a randomized split block design with the two cultivars as the
main block. Results showed that the osmotic potential in the symplasm at full turgor was lower and the
leaf turgor potential at full turgor was higher in tomato leaves in blue light treatment. The water fraction
in the symplasm in the leaf was larger or the apoplastic water fraction was smaller in leaf of blue light
irradiated plants. Both osmotic potential and relative water content at the point of incipient plasmolysis
were lower in tomato leaves in blue light treatment. More leaf water was lost by stomatal transpiration
and less leaf water was lost by cuticular transpiration in leaves of blue light treated tomato plants. Fruit
color was improved and redder in blue light treatment. Fruit yield was increased by all light illumination
treatments. The damage of fruit caused by Helicoverpa armigera worms was more severely in red light
treatment and less severely in blue and white light treatments compared with the control. The leaf blight
index was lower in blue and white light illumination treatments than the red light treatment and the
control. Both cultivars showed LED illumination responses similar to each other although fruit yield was
lower and leaf blight was severer in ‘Baiju’ than in ‘Myoko’. In conclusion, illumination treatment with
blue light from LED as a stimulus was effective in fruit yield increase and quality improvement as well as
improvement in disease resistance of the tomato crop.
The current article presents the results of the influence of lighting conditions on the morphogenetic potential of Ipomoea batatas (L.) microcuttings in vitro. The studied objects were 4 sweet potato cultivars - Jewel, Purple, Porto Rico, Vinnitsa pink. Microcuttings of I . batatas were cultivated in vitro. We used nutrient medium with mineral salts (according to the prescription of Murashige and Skoog (MS)) and medium only with distilled water (without mineral salts). All nutrient media contained sucrose 2% and agar 0.7%. Hormones were not added to the nutrient media. We studied the influence of the different red (R) and far red (FR) ratios, as well as the red and blue light spectrum on the formation of microshoots and the root system. It was shown that the lighting regimes (R and FR ratio) had a stimulating effect on the roots and shoots growth regardless of the medium composition. Moreover, significant results were obtained under conditions of complete nutrition (mineral salts according to MS) in contrast to the control treatment (fluorescent lamps) and the treatment without salts. The best results were obtained at the R=FR treatment. This light treatment can be recommended for inclusion in the technology of clonal micropropagation of sweet potato. When red and blue spectra were added to normal illumination in different proportions, it did not lead to an increase in the morphogenetic potential of cultivated explants. The growth rate (μ) of the main shoot from axillary buds was about 2 times less than in the control treatment.
The aims of this study were to cultivate cos lettuce (Lactuca sativa L. cv. Cos Lettuce) using quantum dot (QD) sheets for wave conversion and to clarify the advantages and disadvantages of this technique for plant cultivation with artificial lighting. Blue LED light was wavelength-converted to green (G-QD) or red (R-QD) light by QD sheets and used for cultivating cos lettuce. Then, lighting with spectral photon flux density distributions similar to those of G-QD and R-QD was designed using green or red LED and blue LED (G-LED and R-LED), respectively, and used for cultivating cos lettuce. Plant growth at 14 days after treatment revealed that the shoot fresh weight was greater under G-QD compared with G-LED, perhaps because the amount of integrated light reception was greater in G-QD owing to the difference in the photosynthetic photon flux density's spatial distribution. Plants showed similar growth levels and morphologies under R-QD and R-LED lights. Plant growth is affected by the light environment, such as spectral photon flux density distributions and its vector field, regardless of the light source. However, the prototype QD sheets used in the present study had low conversion efficiencies and wide directivity angles. If QD products are developed that utilize the advantages of high monochromaticity and long life for plant cultivation at low costs, then they may become widely used.
Soybean breeding involves crossing and inbreeding for multiple generations to develop genetically‐stable lines. The long generation times cause early generations to be the major bottleneck in soybean breeding. Here we tested the effect of red and blue lights (RB) and full spectrum white lights (FS), coupled with 12 h light (29 °C) / 12 h darkness (27 °C) photothermal conditions, on the growth and development of soybean lines and breeding materials of diverse maturity groups in a context of speed breeding. We observed that RB light, when compared to FS lights, reduced plant height but did not affect vegetative biomass, pods and seeds per plants, nor the ability to meet a minimum of one seed per plant. Overall, the RB light treatment reduced the interval planting to physiological maturity by 1.5 d as compared to FS. The period between planting and harvest of mid‐ and late‐maturity soybean ranged from 63 to 81 d, as compared to approximately 120 d observed in field conditions. Also, DAP to R7 was dependent on soybean maturity group. The use of RB lights, coupled with photothermal conditions herein reported, would allow to advance up to 5 generations of US‐adapted soybean under a controlled environment, instead of the 1–3 generations currently possible. This methodology is simple and easily scalable for it maintains stable growing conditions throughout the crop cycle and it allows for simultaneous planting and harvesting within the same growth room. This could have a significant impact in genetic gain of U.S. soybean breeding programs. This article is protected by copyright. All rights reserved
The paper represents the possibilities for substitution of the till now used light sources in plant growing with LED-sources. Two modules with special RGB LEDs and varying intensity are developed. Experimental data with Lettuce and Radicchio are shown.
Dentre os vários insumos utilizados no cultivo do morangueiro, a radiação artificial complementar tem sido ferramenta utilizada em cultivos de alto valor agregado em diversos países do exterior. O objetivo desse trabalho foi avaliar os efeitos agronômicos da complementação com radiação fotossinteticamente ativa em diferentes espectros na cultura do morangueiro, via utilização de lâmpadas fluorescentes em cultivo protegido e sem solo. Utilizou-se delineamento inteiramente casualizado com quatro repetições. A emissão de radiação em diferentes faixas espectrais compuseram os tratamentos, sendo utilizadas para isso lâmpadas fluorescentes de cor branca, azul, vermelha, a combinação de lâmpadas azuis e vermelhas, e a testemunha sem radiação complementar. Foram avaliados aspectos fisiológicos, fenológicos e produtivos. O uso de lâmpadas azuis e vermelhas de forma combinada, e o uso de lâmpadas brancas, anteciparam a floração e aumentaram a massa de frutas produzidas ao longo do ciclo produtivo do morangueiro. A luz azul induziu a produção de frutas com maior massa média. Já a luz vermelha não teve efeitos sobre o aumento da produção nem sobre o adiantamento da floração.
Arrays of blue (B, 400−500 nm) and red (R, 600−700 nm) light-emitting diodes (LEDs) used for plant growth applications make visual assessment of plants difficult compared to a broad (white, W) spectrum. Although W LEDs are sometimes used in horticultural lighting fixtures, little research has been published using them for sole-source lighting. We grew seedlings of begonia (Begonia ×semperflorens), geranium (Pelargonium ×horturum), petunia (Petunia ×hybrida), and snapdragon (Antirrhinum majus) at 20°C under six sole-source LED lighting treatments with a photosynthetic photon flux density (PPFD) of 160 μmol∙m–2∙s–1 using B (peak = 447 nm), green (G, peak = 531 nm), R (peak = 660 nm), and/or mint W (MW, peak = 558 nm) LEDs that emitted 15% B, 59% G, and 26% R plus 6 μmol∙m⁻²∙s⁻¹ of far-red radiation. The lighting treatments (with percentage from each LED in subscript) were MW100, MW75R25, MW45R55, MW25R75, B15R85, and B20G40R40. At the transplant stage, total leaf area, and fresh and dry weight were similar among treatments in all species. Surprisingly, when petunia seedlings were grown longer (beyond the transplant stage) under sole-source lighting treatments, the primary stem elongated and had flower buds earlier under MW100 and MW75R25 compared to under B15R85. The color rendering index of MW75R25 and MW45R55 were 72, and 77, respectively, which was higher than those of other treatments, which were ≤64. While photosynthetic photon efficacy of B15R85 (2.25 μmol∙J–1) was higher than the W light treatments (1.51−2.13 μmol∙J–1), the dry weight gain per unit electric energy consumption (in g∙kWh–1) of B15R85 was similar to those of MW25R75, MW45R55, and MW75R25 in three species. We conclude that compared to B+R radiation, W radiation had generally similar effects on seedling growth at the same PPFD with similar electric energy consumption, and improved the visual color quality of sole-source lighting.
Advancements in light-emitting diode (LED) technology have made them a viable alternative to current lighting systems for both sole and supplemental lighting requirements. Understanding how wavelength specific LED lighting can affect plants is thus an area of great interest. Much research is available on the wavelength specific responses of leaves from multiple crops when exposed to long-term wavelength specific lighting. However, leaf measurements do not always extrapolate linearly to the complexities which are found within a whole plant canopy, namely mutual shading and leaves of different ages. Taken together, both tomato (Solanum lycopersicum) leaves under short-term illumination and lisianthus (Eustoma grandiflorum) and tomato whole plant diurnal patterns of plants acclimated to specific lighting indicate wavelength specific responses of both H2O and CO2 gas exchanges involved in the major growth parameters of a plant. Tomato leaves grown under a white light source indicated an increase in transpiration rate and internal CO2 concentration and a subsequent decrease in water-use-efficiency (WUE) when exposed to a blue LED light source compared to a green LED light source. Interestingly, the maximum photosynthetic rate was observed to be similar. Using plants grown under wavelength specific supplemental lighting in a greenhouse, a decrease in whole plant WUE was seen in both crops under both red-blue (RB) and red-white (RW) LEDs when compared to a high pressure sodium (HPS) light. Whole plant WUE was decreased by 31% under the RB LED treatment for both crops compared to the HPS treatment. Tomato whole plant WUE was decreased by 25% and lisianthus whole plant WUE was decreased by 15% when compared to the HPS treatment when grown under RW LED. The understanding of the effects of wavelength specific lighting on both leaf and whole plant gas exchange has significant implications on basic academic research as well as commercial greenhouse production.
In this study, effects of yellow (Y), purple (P), red (R), blue (B), green (G), and white (W) light on growth and development of tobacco plants were evaluated. We showed that monochromatic light reduced the growth, net photosynthetic rate (PN), stomatal conductance, intercellular CO2, and transpiration rate of tobacco. Such a reduction in PN occurred probably due to the stomatal limitation contrary to plants grown under W. Photochemical quenching coefficient (qP), maximal fluorescence of dark-adapted state, effective quantum yield of PSII photochemistry (ΦPSII), and maximal quantum yield of PSII photochemistry (Fv/Fm) of plants decreased under all monochromatic illuminations. The decline in ΦPSII occurred mostly due to the reduction in qP. The increase in minimal fluorescence of dark-adapted state and the decrease in Fv/Fm indicated the damage or inactivation of the reaction center of PSII under monochromatic light. Plants under Y and G showed the maximal nonphotochemical quenching with minimum PN compared with the W plants. Morphogenesis of plants was also affected by light quality. Under B light, plants exhibited smaller angles between stem and petiole, and the whole plants showed a compact type, while the angles increased under Y, P, R, and G and the plants were of an unconsolidated style. The total soluble sugar content increased significantly under B. The reducing sugar content increased under B but decreased significantly under R and G compared with W. In conclusion, different monochromatic light quality inhibited plants growth by reducing the activity of photosynthetic apparatus in plants. R and B light were more effective to drive photosynthesis and promote the plant growth, while Y and G light showed an suppression effect on plants growth. LEDs could be used as optimal light resources for plant cultivation in a greenhouse.
Despite decades of research, the effects of spectral quality on plant growth, and development are not well understood. Much of our current understanding comes from studies with daily integrated light levels that are less than 10% of summer sunlight thus making it difficult to characterize interactions between light quality and quantity. Several studies have reported that growth is increased under fluorescent lamps compared to mixtures of wavelengths from LEDs. Conclusions regarding the effect of green light fraction range from detrimental to beneficial. Here we report the effects of eight blue and green light fractions at two photosynthetic photon fluxes (PPF; 200 and 500 μmol m⁻² s⁻¹; with a daily light integral of 11.5 and 29 mol m⁻² d⁻¹) on growth (dry mass), leaf expansion, stem and petiole elongation, and whole-plant net assimilation of seven diverse plant species. The treatments included cool, neutral, and warm white LEDs, and combinations of blue, green and/or red LEDs. At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively, but there was no statistically significant effect on radish, soybean, lettuce or wheat. At the lower PPF (200), increasing blue light reduced growth only in tomato (41%). The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation. In contrast to the significant effects of blue light, increasing green light in increments from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at either low or high PPF. Surprisingly, growth of three of the seven species was not reduced by a treatment with 93% green light compared to the broad spectrum treatments. Collectively, these results are consistent with a shade avoidance response associated with either low blue or high green light fractions.
Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture.
Pansy (Viola cornuta) is a facultative long-day plant that flowers from October until March in Turkey. During the winter months, low light levels can limit plant growth and development. Light emitting diodes (LEDs) can provide supplemental lighting in greenhouses which produce same light intensity with less energy than conventional incandescent lighting. Light emitting diode technologies have enabled affordable and efficient light systems to be installed in greenhouses and plastic tunnels in the field. In this experiment we evaluated the effects of supplemental red-orange LED lightening on the growth and development of pansy cv. Blue Blotch grown in plastic tunnels. The energy, which LEDs are to consume, was provided through a solar panel system with the aim of drawing attention to the cleanliness of solar energy source. Five hours of supplement LED lighting was applied after dusk starting from November to February. Pansy growth and development parameters were compared with non-light supplied control plants. Supplemental LED lighting significantly increased plant biomass weight, flower number and leaves number at the rate of 52%, 72%, and 47%, respectively. Moreover, LED lighting increased plant growth rate (0.109 and 0.306 g of fresh weight), compared with the no light control. LED lighting, however, had no effect on length of stems, number of branches and the diameter of flowers. Thus, this study indicated that pansies are light limited during the winter months and supplemental LED lighting can significantly increase pansy growth and development. © 2015, Sociedade de Olericultura do Brasil. All rights reserved.
This paper is suitable for household plant factory by design and using both energy-saving LED and solar technology. Conventional household plant factory only depending on natural sunlight is sensitive for the change of external environment. Another a big problem of conventional common household plant factory is large power consumption. Recently interest in wellbeing food such as chemical-free is increased abruptly. To solve these two problems, this paper describes hybrid type of household plant. In particular, reducing the power photosynthesis photon flux density (PPFD) is kept uniform to enhance the growth of the plant. Ambient light sensor is adopted for the control of proper combination of sunlight and LED to keep PPFD constant.
The effect of light (blue, red, and/or green) generated by light-emitting diodes on shoot regeneration was examined in selected clones, ‘I-476’ and ‘Dorskamp’, of Populus euramericana. We found that a combination of red and blue light produced the highest percentage of shoot regeneration in comparison to monochromic or fluorescent light. Further studies of light quality and in vitro growth of “Dorskamp” plantlets demonstrated the suitability of combinations of red and blue light to improve most of the characteristics studied. Flow cytometry of the leaves showed that 50 % red + 50 % blue light treatment was the most effective for inducing cell division in “Dorskamp”, whereas monochromic red and blue were more effective in “I-476”. Histological studies found that secondary xylem formation increased with the monochromic blue light treatment in the stem of “I-476”, whereas in “Dorskamp”, a combination of red and blue light (70 + 30 %, respectively) was more suitable. Our study demonstrated that combinations of red and blue light increase shoot regeneration and development by stimulation of cell division, although the response may vary among genotypes of the same species. The results of this study can contribute to mass production of the selected clones for forest establishment on reclaimed land and serve as an efficient protocol for genetic transformation of this species.
We investigated the effects of various ratios of red to far-red light-emitting diodes (LEDs) on growth characteristics, physiological response, and cell division of red leaf lettuce. Sixteen-day-old lettuce seedlings were transferred into growth chambers and cultivated under various ratios of red (R) and far-red (FR) LEDs (R/FR = 0.7, 1.2, 4.1, and 8.6), only red LEDs (RED), or fluorescent lamps (control) for 22 days. Growth characteristics were measured at 11 and 22 days of treatment. In addition, cell division rate, epidermal cell density, chlorophyll fluorescence, and photosynthesis of leaves were analyzed. Fresh and dry weights and leaf area in all R/FR treatments were higher than those in the control at 22 days of treatment. The R/FR 1.2 had the highest values among R/FR treatments. The number of leaves appeared to increase as R/FR ratio increased. The specific leaf weights in the R/FR ratio of 0.7, 1.2, and 8.6 were similar to the control at 22 days of treatment. The SPAD values in all R/FR treatments were lower than that in the control. All R/FR treatments led to a longer leaf shape than the control. The percentage of cells in the G2M phase, indicating the cell division rate, increased in the R/FR treatments after 4 days of treatment, which supported the growth improvement in the R/FR treatments. The Fv/Fm and the photosynthetic rate in all treatments decreased due to the absence of blue light. The results of this study suggest that the supplementation with far-red LEDs should be considered when designing artificial lighting systems for closed-type plant factories since far-red light affects the vegetative growth of leafy vegetables such as lettuce.
In the present study, we investigated the effects of supplemental lighting (SL) with white, red, and blue light-emitting diodes (LEDs) on the yield and quality of tomato grown under the single-truss tomato production system (STTPS). SL was applied for 28 days during the rapid fruit development stage. Based on the same power consumption, the light treatments with the white and red LEDs increased the fresh yield of tomato by 12 and 14%, and the dry yield by 16 and 14%, compared with the control (without SL), respectively. Based on the unit photons emitted, the white LEDs showed high efficiency as the red LEDs in increasing tomato yield, followed by the blue ones. The results were probably due to the white LEDs that contained more than 50% of green light characterized by high penetration into the canopy. The sugar and ascorbic acid contents were not affected by SL from the LEDs. These results indicated that the white and red LEDs were effective in enhancing tomato yield and, in particular, the white LEDs with a combination of red, blue, and abundent green light would be more suitable to the use of STTPS at a high plant density.
Microalgae could become an important renewable source for chemicals, food, and energy if process costs can be reduced. In the past 60 years, relevant factors in open outdoor mass cultivation of microalgae were identified and elaborate solutions regarding bioprocesses and bioreactors were developed. An overview of these solutions is presented. Since the cost of most microalgal products from current mass cultivation systems is still prohibitively high, further development is required. The application of complex computational techniques for cost-effective process and reactor development will become more important if experimental validation of simulation results can easily be achieved. Due to difficulties inherent to outdoor experimentation, it can be useful to conduct validation experiments indoors. Considerations and approaches for realistic indoor reproduction of the most important environmental conditions in microalgae cultivation experiments-light, temperature, and substance concentrations, are discussed.
This study proposes a method of optimizing plant growth in control environment using led lighting system. Indoor farming system can cultivate varieties of plant mainly vegetables. Research on indoor farming using Led as a light source for plant photosynthesis has becoming high in demand due to uncertainty of weather and pest mortality. Red / Blue (RB) LEDs combination of ratio 16:4 as light source has been used to simulate actual sun light radiation and has similar absorption spectrum of the plant photosynthesis. Optimizing plant growth with climate control system to maintain and monitor humidity, temperature and light intensity is a must to ensure the survival of the plant and is proposed for the system. The system of data logger capability to acquire data and perform analytical work after each experiment performs. The study compares the effect of plant growth with different amount of light exposed. The finding from the experiment has shown very significant result for plant with pulse lighting control system of 1-hour duration with 15 minutes light off period as compared to typical photoperiod at 12 hours continuous lighting system and 12 hours light off period. From data analysis, we conclude that the plant with pulse light treatment which was recorded 291% higher photosynthesis rates is having better growth rates compared to conventional 12 hours lighting system.
While a plant utilizes the full spectrum of visible light, some colours of light have more important applications than others. The aim of this study was to evaluate the responses of bell pepper plants grown under coloured covers. Bell pepper plants (Capsicum annuum) were grown hydroponically in a greenhouse in Tunja, Colombia, under different light quality regimes that were obtained with polypropylene films (yellow, green, blue, transparent, red, and a control without a plastic film cover). Conventional growth indices were calculated or measured as response variables. All of the evaluated parameters were influenced in a different ways by the colour of the covers, e.g. the leaf area was higher under the green and blue covers. The highest water uptake was found in the plants grown under the blue film. Plants under the yellow cover presented higher water use efficiency than the other treatments. The chlorophyll content index was higher under the blue, green and transparent covers. Based on these results, a coloured cover that favors most of the growth indices of plants cannot be selected; however, according to the needs of growers, the supplemental light quality can be used to achieve a specific effect.
Effect of light provided by various light intensities combined with different photoperiods on the growth and morphogenesis of lettuce (Lactuca sativa L.) ‘Hongyeom Jeockchukmyeon’ in a closed-type plant factory system were evaluated in this study. Four light intensity treatments, i.e., 200, 230, 260, and 290 μmol·m−2·s−1 PPFD, provided from light-emitting diodes (LEDs), with a combination of three different photoperiods 18/6 (1 cycle), 9/3 (2 cycles) or 6/2 (3 cycles) (light/dark) were used. The combination of 290-9/3 (light intensity-photoperiod) showed the highest plant height and fresh shoot weight, while plants grown at 290-18/6 exhibited the greatest root fresh weight, leaf dry weight, and longest root length. The greatest leaf width, maximum number of leaves, and greatest root dry weight were observed in the treatment combination of 290-6/2. Anthocyanin content was found to be highest in the 290-6/2 and lowest in the 200-6/2 treatment, whereas chlorophyll fluorescence was observed to be highest in the 260-6/2 and the lowest in the 290-9/3 treatment. Our data showed that providing a high light intensity of 290 μmol·m−2·s−1 PPFD with a shorter photoperiod of 6/2 (light/dark) resulted in good plant growth and development of lettuce, whereas growth at light intensities of 230 or 260 μmol·m−2·s−1 PPFD with longer photoperiods of 18/6 and 9/3 (light/dark) resulted in good growth as well as higher photosynthetic capacity.
The effect of light source and DIF (difference between light and dark-period temperatures) on the growth and anthocyanin concentration of Perilla frutescens var. acuta Kudo grown in a growth chamber was examined. The plant was grown under 140 μmol·m−2·s−1 PPF provided by either cool white fluorescent lamps (FL, the control), white (W) light emitting diodes (LEDs), or a 8:1:1 mixture of red, blue and white (RBW) LEDs. Temperatures during the light-/dark-period were maintained at either 24/16 (+8 DIF), 22/18 (+4 DIF), or 20/20°C (0 DIF) with a daily mean temperature of 20°C in all treatments. Plant height increased in the FL as compared to the W and RBW LEDs treatments with +8 and +4 DIF. The RBW LEDs treatment promoted vegetative growth of the shoot and root. Chlorophyll fluorescence (Fv/Fm) was not significantly affected by the light source and DIF. Total anthocyanin concentration per leaf in the +8 DIF was higher in the RBW LEDs treatment than the other treatments. The results suggested that the RBW LEDs was the most suitable light source not only for vegetative growth, but also for the accumulation of anthocyanin under a controlled environment.
The effect of light source and CO2 concentration on the growth and anthocyanin content of lettuce (Lactuca sativa L. ‘Seonhong Jeokchukmyeon’) grown in growth chambers was examined. The plant was grown under 140 μmol· m−2·s−1 PPF provided by either cool white fluorescent lamps (F, the control), white (W) light emitting diodes (LEDs), or a 8:1:1 mixture of red, blue and white (RBW) LEDs. Carbon dioxide concentration of the atmosphere was maintained at either 350, 700, or 1,000 μmol·mol−1. The RBW treatment promoted vegetative growth of the shoot and root. Chlorophyll fluorescence (Fv/Fm) was not significantly affected by the light source and CO2 concentration. Total anthocyanin content of the plant supplied with 1,000 mol·mol−1 CO2 was the greatest in the F treatment. Photosynthetic rate significantly increased with the increasing CO2 concentration. These results suggested that the RBW which provided a wider spectrum of PAR and the highest CO2 concentration provided the most the suitable environment condition for vegetative growth of lettuce among the tested light sources. To obtain plants with even higher quality, especially having greater content of anthocyanin, however, more considerations on supplemental light source including white LED are necessary in terms of optimum intensity, photoperiod, and optimum ratios of mixing with other LEDs.
Advances in plant tissue culture methods with regard to lighting requirements are currently focused on the improved features of light-emitting diodes (LEDs). Over the years, the steady development of LED technology, with the emergence of new types of semi-conductor materials, has made it possible to apply it in an increasing number of new areas. As an alternative to conventional lighting systems, LED has been demonstrated to be an artificial flexible lighting source for plant tissue culture. Numerous studies have been conducted in order to investigate the effects of LED on plants, which have led to many satisfactory results. Various morphological, anatomical, and physiological attributes, such as shoot elongation, axillary shoot formation, somatic embryo induction, rhizogenesis, leaf anatomy, and photosynthetic abilities of plants grown in vitro have found to be regulated by spectral properties of LEDs. The present review gives an overview of the fundamentals of LEDs and describes their effects on in vitro plant growth and morphogenesis and their future potentials.
We used red light-emitting diodes (LEDs, R) and blue light-emitting diodes (LEDs, B) to obtain the different light intensities of uniform spectra and investigated the effects of different light intensities on growth and leaf development of young tomato plants. The results showed that fresh weight, dry weight, stem diameter and health index were superior in plants grown under 300, 450 and 550 μmol m−2 s−1. The energy efficiency was highest under 300 μmol m−2 s−1. When photosynthetic photon flux density (PPFD) increased from 50 to 550 μmol m−2 s−1, a decrease in the specific leaf area (SLA) was observed. Under 300 and 450 μmol m−2 s−1, the thickness of leaves, palisade parenchyma and spongy parenchyma were the bigger, and the stomatal frequency and stomatal area per unit leaf area were also higher. The highest net photosynthesis rate (Pn) was observed under 300 μmol m−2 s−1. Our results implied that, compared to other light treatments, 300 μmol m−2 s−1 was more suitable for the culture of young tomato plants and there was no substantial gain from a PPFD above 300 μmol m−2 s−1.
The effects of different spectral light distribution on in vitro induction and proliferation of Oncidium protocorm-like bodies (PLBs) and subsequent growth of plantlets were investigated. Shoot tips (5mm in length) of proliferating
shoots of Oncidium “Gower Ramsey” were vertically incubated on 1/2 Murashige and Skoog (MS) medium supplemented with 1.0mgl−1 6-benzyladenine (BA), and grown under either monochromatic red light-emitting diodes (LEDs) (RR), blue LEDs (BB), yellow
LEDs (YY) or green LEDs (GG). Cultures grown under fluorescent lamps (FL) were used as control. Selected FL-induced PLBs were
cut into 3- to 4-mm sections and incubated on MS medium supplemented with 1.0mgl−1 BA and 0.5mgl−1 α-naphthaleneacetic acid (NAA), and grown under RR, BB, YY, GG, or FL. Moreover, FL-differented shoots (15mm in length with
two leaves) were incubated on 1/2 MS medium with 0.5mgl−1 NAA, and grown under either FL, RR, 10% blue+90% red LEDs (1BR), 20% blue+80% red LEDs (2BR), 30% blue+70% red LEDs
(3BR), BB, 80% red+10% blue+10% far-red LEDs (RBFr), or 80% red+10% blue+10% green LEDs (RBG). Overall, the red light
spectrum enhanced induction, proliferation, and the carbohydrate contents of PLBs, as well as subsequent plantlet lengths,
while the blue spectrum promoted differentiation, protein accumulation, and enzyme activities in PLBs, as well as pigment
content accumulation in PLBs and developing plantlets. The combination of red and blue LEDs resulted in higher energy efficiency
as well as dry weight and enzyme activities in these plantlets.
KeywordsSpectral distribution–LEDs–
Oncidium
–PLB–Induction–Proliferation–Plantlets in vitro
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