Effects of light quality on growth and development of protocorm-like bodies of <Emphasis Type="Italic">Dendrobium officinale</Emphasis> in vitro

The effect of light quality on protocorm-like bodies (PLBs) of Dendrobium officinale was investigated. PLBs of D. officinale were incubated under a number of different light conditions in vitro, namely: dark conditions; fluorescent white light (Fw); red light-emitting diodes (LEDs); blue LEDs; half red plus half blue [RB (1:1)] LEDs; 67% red plus 33% blue [RB (2:1)] LEDs; and 33% red plus 67% blue [RB (1:2)] LEDs. Growth parameters, number of shoots produced per PLB, chlorophyll concentration and carotenoid concentration were measured after 90 days culture. The percentage of PLBs producing shoots was 85% under blue LEDs. In contrast, the percentage of PLBs producing shoots was less than 60% under dark conditions, fluorescent white light and red LEDs. The number of shoots produced per PLB was more than 1.5 times greater under blue LEDs, RB (1:1) LEDs and RB (1:2) LEDs than those cultured under other light treatments [dark, Fw, red LEDs and RB (2:1)]. Chlorophyll and carotenoid concentrations were significantly higher under blue LEDs and different red plus blue LED ratios, compared to other light treatments (dark, Fw and red LEDs). Blue LEDs, Fw, and RB (1:2) LEDs produced higher dry matter accumulations of PLBs and shoots. This study suggests that blue LEDs or RB (1:2) LEDs could significantly promote the production of shoots by protocorm-like bodies of D. officinale and increase the dry matter of PLBs and the accumulation of shoot dry matter in vitro.     

Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting

Red light-emitting diodes (LEDs) are a potential light source for growing plants in spaceflight systems because of their safety, small mass and volume, wavelength specificity, and longevity. Despite these attractive features, red LEDs must satisfy requirements for plant photosynthesis and photomorphogenesis for successful growth and seed yield. To determine the influence of gallium aluminium arsenide (GaAlAs) red LEDs on wheat photomorphogenesis, photosynthesis, and seed yield, wheat (Triticum aestivum L., cv. 'USU-Super Dwarf') plants were grown under red LEDs and compared to plants grown under daylight fluorescent (white) lamps and red LEDs supplemented with either 1% or 10% blue light from blue fluorescent (BF) lamps. Compared to white light-grown plants, wheat grown under red LEDs alone demonstrated less main culm development during vegetative growth through preanthesis, while showing a longer flag leaf at 40 DAP and greater main culm length at final harvest (70 DAP). As supplemental BF light was increased with red LEDs, shoot dry matter and net leaf photosynthesis rate increased. At final harvest, wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to plants grown under white light. Wheat grown under red LEDs+10% BF light had comparable shoot dry matter accumulation and seed yield relative to wheat grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.     

Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting

Red light-emitting diodes (LEDs) are a potential light sourcefor growing plants in spaceflight systems because of their safety,small mass and volume, wavelength specificity, and longevity.Despite these attractive features, red LEDs must satisfy requirementsfor plant photosynthesis and photomorphogenesis for successfulgrowth and seed yield. To determine the influence of galliumaluminium arsenide (GaAIAs) red LEDs on wheat photomorphogenesis,photosynthesis, and seed yield, wheat (Triticum aestivum L.,cv. ‘USU-Super Dwarf’) plants were grown under redLEDs and compared to plants grown under daylight fluorescent(white) lamps and red LEDs supplemented with either 1% or 10%blue light from blue fluorescent (BF) lamps. Compared to whitelight-grown plants, wheat grown under red LEDs alone demonstratedless main culm development during vegetative growth throughpreanthesis, while showing a longer flag leaf at 40 DAP andgreater main culm length at final harvest (70 DAP). As supplementalBF light was increased with red LEDs, shoot dry matter and netleaf photosynthesis rate increased. At final harvest, wheatgrown under red LEDs alone displayed fewer subtillers and alower seed yield compared to plants grown under white light.Wheat grown under red LEDs+10% BF light had comparable shootdry matter accumulation and seed yield relative to wheat grownunder white light. These results indicate that wheat can completeits life cycle under red LEDs alone, but larger plants and greateramounts of seed are produced in the presence of red LEDs supplementedwith a quantity of blue light. Key words: Triticum aestivum L., red light, blue light, subtillering, bioregenerative advanced life support     

Responses of strawberry plantlets cultured in vitro under superbright red and blue light-emitting diodes (LEDs)

Unrooted strawberry cv. `Akihime' shoots with three leaves obtained from standard mixotrophic cultures were cultured in the ``Culture Pack'-rockwool system with sugar-free MS medium under CO<sub>2</sub>-enriched condition. To examine the effect of superbright red and blue light-emitting diodes (LEDs) on in vitro growth of plantlets, these cultures were placed in an incubator, ``LED PACK', with either red LEDs, red LEDs1blue LEDs or blue LEDs light source. To clarify the optimum blue and red LED ratio, cultures were placed in ``LED PACK 3' under LED light source with either 100, 90, 80, or 70% red + 0, 10, 20, 30% blue, respectively, and also under standard heterotrophic conditions. To determine the effects of irradiation level, cultures were grown under 90% red LEDs + 10% blue LEDs at 45, 60 or 75 mol m^–2 s^–1 . Plantlet growth was best at 70% red + 30% blue LEDs. The optimal light intensity was 60 mol m^–2 s^–1. Growth after transfer to soil was also best after in vitro culture with plantlets produced were 70% red LEDs + 30% blue LEDs.     

LED light for in vitro and ex vitro efficient growth of economically important highbush blueberry (<Emphasis Type="Italic">Vaccinium corymbosum</Emphasis> L.)

Light-emitting diodes (LEDs) are useful for the growth of many plants, but not known for blueberry species. This study examined the effects of fluorescent lamps and 100 % red, 80 % red plus 20 % blue, 50 % red plus 50 % blue, and 100 % blue LEDs on the growth and development of highbush blueberry shoots under aseptic and non-aseptic conditions. Results revealed that monochromatic blue LEDs accumulated the highest contents of leaf chlorophylls. In contrast, monochromatic red LEDs inhibited chlorophyll accumulation, but produced the longest shoots and roots and provided high percentages of side shoot formation from ex vitro plants. Mixed LEDs, particularly 50 % red plus 50 % blue light, improved plant growth with respect to notably increased shoot and root biomass. Direct rooting of in vitro shoots under non-aseptic conditions was readily achieved using a commercial mixture of perlite and peat moss with high humidity controls. These findings obviously suggest the efficient use of LEDs to replace traditional fluorescent lamps in large-scale propagation of the highbush blueberry, and also pave the way for future studies on LEDs for standardizing micropropagation protocols to shrub crops and woody plants.     

Retinal damage induced by commercial light emitting diodes (LEDs)

Spectra of “white LEDs” are characterized by an intense emission in the blue region of the visible spectrum, absent in daylight spectra. This blue component and the high intensity of emission are the main sources of concern about the health risks of LEDs with respect to their toxicity to the eye and the retina. The aim of our study was to elucidate the role of blue light from LEDs in retinal damage. Commercially available white LEDs and four different blue LEDs (507, 473, 467, and 449 nm) were used for exposure experiments on Wistar rats. Immunohistochemical stain, transmission electron microscopy, and Western blot were used to exam the retinas. We evaluated LED-induced retinal cell damage by studying oxidative stress, stress response pathways, and the identification of cell death pathways. LED light caused a state of suffering of the retina with oxidative damage and retinal injury. We observed a loss of photoreceptors and the activation of caspase-independent apoptosis, necroptosis, and necrosis. A wavelength dependence of the effects was observed. Phototoxicity of LEDs on the retina is characterized by a strong damage of photoreceptors and by the induction of necrosis.     

Light emitting diode(LED)‐based trapping of the greenhouse whitefly (Trialeurodes vaporariorum)

Visual traps like yellow sticky card traps are used for monitoring and control of the greenhouse whitefly (Trialeurodes vaporariorum). However, reflected intensity (brightness) and hence, attractiveness depend on the ambient light conditions, and the colour (wavelength) might not fit with the sensitivity of whitefly photoreceptors. The use of light emitting diodes (LEDs) is a promising approach to increase the attractiveness, specificity and adaptability of visual traps. We constructed LED‐based visual traps equipped with blue and green high‐power LEDs and ultraviolet (UV) standard LEDs according to the putative spectral sensitivities of the insects' photoreceptors. In a series of small‐scale choice and no‐choice recapture experiments, the factors time of day as well as light intensity and light quality (colour) of LED traps were studied in terms of attractiveness compared to yellow traps without LEDs. Green LED traps (517 nm peak wavelength) were comparably attractive in no‐choice experiments but clearly preferred over yellow traps in all choice experiments. The time of day had a clear effect on the flight activity of the whiteflies and thereby on the trapping success. Blue LEDs (474 nm) suppressed the attractiveness of the light traps when combined with green LEDs suggesting that a yet undetected photoreceptor, sensitive for blue light, and an inhibiting interaction with the green receptor, might exist in T. vaporariorum. In choice experiments between LED traps emitting green light only or in combination with UV (368 nm), the green‐UV combination was preferred. In no‐choice night‐time experiments, UV LEDs considerably increased whitefly flight activity and efficacy of trapping. Most likely, the reason for the modifying effect of UV is the stimulating influence on flight activity. In conclusion, it seems that the use of green LEDs alone or in combination with UV LEDs could be an innovative option for improving attractiveness of visual traps.     

Multiple night‐time light‐emitting diode lighting strategies impact grassland invertebrate assemblages

White light‐emitting diodes (LEDs) are rapidly replacing conventional outdoor lighting technologies around the world. Despite rising concerns over their impact on the environment and human health, the flexibility of LEDs has been advocated as a means of mitigating the ecological impacts of globally widespread outdoor night‐time lighting through spectral manipulation, dimming and switching lights off during periods of low demand. We conducted a three‐year field experiment in which each of these lighting strategies was simulated in a previously artificial light naïve grassland ecosystem. White LEDs both increased the total abundance and changed the assemblage composition of adult spiders and beetles. Dimming LEDs by 50% or manipulating their spectra to reduce ecologically damaging wavelengths partially reduced the number of commoner species affected from seven to four. A combination of dimming by 50% and switching lights off between midnight and 04:00 am showed the most promise for reducing the ecological costs of LEDs, but the abundances of two otherwise common species were still affected. The environmental consequences of using alternative lighting technologies are increasingly well established. These results suggest that while management strategies using LEDs can be an effective means of reducing the number of taxa affected, averting the ecological impacts of night‐time lighting may ultimately require avoiding its use altogether.     

Mounting of the transducers in measurement of segmental motion of the spine

A seated female subject was subjected to sinusoidal whole body vibration at 2, 4, 5 and 6 Hz. Accelerations were measured by accelerometers on pins screwed into the spinous process. The pins were also fitted with light emitting diodes (LED). The displacement of these LEDs were compared to LEDs attached directly to the skin. Substantial differences in measured displacements were noted between surface mounted LEDs and those mounted on pins rigidly attached to the skeleton. These differences were more marked further out from the center line.     

Effects of different spectral lights on <Emphasis Type="Italic">Oncidium</Emphasis> PLBs induction,proliferation, and plant regeneration

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 (5 mm in length) of proliferating shoots of Oncidium “Gower Ramsey” were vertically incubated on 1/2 Murashige and Skoog (MS) medium supplemented with 1.0 mg l⁻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 1.0 mg l⁻¹ BA and 0.5 mg l⁻¹ α-naphthaleneacetic acid (NAA), and grown under RR, BB, YY, GG, or FL. Moreover, FL-differented shoots (15 mm in length with two leaves) were incubated on 1/2 MS medium with 0.5 mg l⁻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.     

Blue and red light-emitting diodes with or without sucrose and ventilation affect in vitro Growth ofRehmannia glutinosa plantlets

Single-node, in vitro cuttings ofRehmannia glutinosa were transplanted to MS basal media and grown for 30 d. Plantlets were grown under various culture conditions: four different light qualities (red LEDs, blue LEDs, mixed LEDs, and fluorescent); with sucrose (30 mg.L^-1) or without (0 mg.L^-1); with air exchanges (3.5 h.^-1) or without (0.1 h.L^-1). Highest dry weights were obtained from plantlets under blue LEDs with 3.5h.L^-1 air exchanges. Light source did not affect shoot elongation in ventilated conditions, but without ventilation, the shoots of plantlets under red LEDs were twice as long as for plantlets growing under other types of lighting. Plantlets grown without sucrose showed little difference in photosynthesis under any of the tested light qualities. In contrast, the photosynthetic rate of those in the sucrose-containing media varied according to light source.     

LED光源对不同品种生菜生长和品质的影响

以自然光为对照(CK),探讨了LED红光(R)、蓝光(B)和红蓝组合光(RB)对不同品种生菜生长与品质的影响.结果显示:(1)不同光质处理的4个品种生菜的根长、株高及生物量积累等形态及生长指标具有相同的变化规律.(2)植株干鲜重、叶面积及根系活力在R和RB处理下都较大,而在B处理下较小;金祥、高华和永荣的B处理植株可溶性蛋白含量较高;联记、金祥和高华植株的淀粉含量在RB处理下较多,而永荣在R处理下较多;各品种植株可溶性糖含量在R和RB处理下较高,而永荣植株RB处理蔗糖含量较高,其余品种蔗糖含量在R处理下较高;金祥、高华和永荣VC含量在B和RB下较高,联记在RB下较高,各品种在R下均较低;植株总酚含量在各光质处理间无显著差异.(3)联记的硝态氮含量及亚硝酸还原酶对光质敏感,B处理能降低其硝态氮含量及亚硝酸还原酶活性,其他品种的硝态氮含量及亚硝酸还原酶活性在光质处理间无显著差异.研究表明,相同光质下品种间生长无显著差异,而各品种生菜植株在红光和红蓝组合光下生长较好,在红蓝光处理下品质较优,红蓝光是设施栽培生菜的良好光源.     

Experimentally comparing the attractiveness of domestic lights to insects: Do LEDs attract fewer insects than conventional light types?

LED lighting is predicted to constitute 70% of the outdoor and residential lighting markets by 2020. While the use of LEDs promotes energy and cost savings relative to traditional lighting technologies, little is known about the effects these broad‐spectrum “white” lights will have on wildlife, human health, animal welfare, and disease transmission. We conducted field experiments to compare the relative attractiveness of four commercially available “domestic” lights, one traditional (tungsten filament) and three modern (compact fluorescent, “cool‐white” LED and “warm‐white” LED), to aerial insects, particularly Diptera. We found that LEDs attracted significantly fewer insects than other light sources, but found no significant difference in attraction between the “cool‐” and “warm‐white” LEDs. Fewer flies were attracted to LEDs than alternate light sources, including fewer Culicoides midges (Diptera: Ceratopogonidae). Use of LEDs has the potential to mitigate disturbances to wildlife and occurrences of insect‐borne diseases relative to competing lighting technologies. However, we discuss the risks associated with broad‐spectrum lighting and net increases in lighting resulting from reduced costs of LED technology.     

Light trapping of biting midges Culicoides spp. (Diptera: Ceratopogonidae) with green light-emitting diodes

Abstract  A study of responses by Culicoides spp. to light traps with light-emitting diodes (LEDs) confirmed that the livestock virus vector, Culicoides brevitarsis Kieffer, was preferentially attracted to green light. Four species shown previously to respond to blue light exhibited significantly higher responses to ultraviolet (UV) light. Field trials comparing green LEDs with incandescent lights in New South Wales, Northern Territory and East Timor confirmed the superiority of green LEDs for catching C. brevitarsis . The green LED traps also had a significant advantage over incandescent traps for a wide range of Culicoides species. These included: species whose ultimate preference was for UV, most species that are proven or potential vectors of viruses affecting Australian livestock and native animals and the main species affecting humans in northern Australia. Use of green LEDs has been adopted for trapping C. brevitarsis , especially in its marginal and low-density areas, and for detecting incursions of new Culicoides spp. into Australia. Use could be possible for species in other insect Orders.     

Use of ultrabright LEDs for the determination of static and time-resolved florescence information of liquid and solid crude oil samples

Ultrabright light emitting diodes (LEDs) are an inexpensive alternative to laser diodes (LDs) and other short wavelength emitting light sources. They have a high stability, a long lifetime, and a very low power consumption. A large number of publications are already available for fluorescence applications using this type of LEDs. Most of them are describing fluorescence intensity measurements. Only some of them are dealing with time-resolved methods, like single photon timing. LED modulation fluorometry is a very recent application, which can also be used for environmental investigations, like the detection of polycyclic aromatic hydrocarbons (PAHs). This article demonstrates the possible application of ultrabright LEDs for the time-resolved fluorescence detection of crude oil contaminated samples.     

Modified light spectral conditions prior to cryopreservation alter growth characteristics and cryopreservation success of potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) shoot tips in vitro

Light is one of the most important factors affecting growth and morphogenesis of plants. Light intensity, photoperiod and spectral composition greatly affect morphogenetic responses of in vitro plants. Modification of light spectra during recovery after cryopreservation improves survival and regeneration, but the effect of modified light conditions prior to cryopreservation are not known. Therefore, the aim of the present study was to follow the photomorphogenetic response of potato plants (Solanum tuberosum L.) under different light qualities i.e. cool white fluorescent (CW) used as control, warm white (HQI), white LEDs (W), blue LEDs (B), red LEDs (R) and a combination of red with 10?% of blue LEDs (RB) prior to cryopreservation, affecting recovery of cultivars Agrie Dzeltenie, Bintje, Maret, Anti and Désirée in vitro. Light spectral quality had a significant effect on growth characteristics of potato plants in vitro. Red light (R) promoted elongation growth but biomass accumulation remained low under monochromatic light treatments. Some of the pre-cryopreservation light treatments significantly affected post-cryopreservation success. Under blue LEDs, high early recovery was observed for all cultivars tested, whereas under red (R) or (HQI), lowest survival percentages were obtained 2–4 weeks after thawing. Specifically, during early recovery, blue light increased survival from 26 to 66?%, 4 to 31?% and 16 to 48?% for cultivars Agrie Dzeltenie, Anti, and Désirée, compared to illumination by red LEDs. Therefore, light spectral quality prior to cryopreservation can significantly affect the cryopreservation success of potato shoot tips.     

Red and Blue Light Emitting Diodes (LEDs) Participate in Mitigation of Hyperhydricity in In Vitro-Grown Carnation Genotypes (<Emphasis Type="Italic">Dianthus Caryophyllus</Emphasis>)

The present study was to determine the factors that can reduce hyperhydricity in in vitro-propagated carnation genotypes. The carnation genotypes (Green Beauty, Purple Beauty, and Inca Magic) were grown in vitro under normal and hyperhydric conditions in white fluorescent light (FL) in which half of the hyperhydric plants were grown in red and blue LEDs (light emitting diodes). It was observed that hyperhydricity leads to oxidative stress in terms of TBARS (thiobarbituric acid reactive substances) content, whereas stress was alleviated by R (red) and B (blue) LEDs. The multiprotein complex proteins such as ATPase (RCI?+?LHC1) PSII-core dimer, PSII-monomer/ATPs synthase, and PSII-monomer/cyt b₆f had decreased levels in hyperhydric conditions grown in white FL; however, the expression level of these photosynthetic proteins was retained in hyperhydric plants grown in R and B LEDs. Moreover, the immunoblots of two photosynthetic proteins (PsaA and PsbA) and stress-responsive proteins such as superoxide dismutase, ascorbate peroxidase, and catalase showed recovery of hyperhydricity in carnation genotypes grown in R and B LEDs. Our present study signifies that red (R) and blue light (B) LEDs reduced the hyperhydricity to control levels by maintaining the composition of thylakoid proteins and antioxidative defense mechanisms in carnation genotypes.     

Assembly of light‐emitting diode based on hydrophilic CdTe quantum dots incorporating dehydrated silica gel

Stable photoluminescence QD light‐emitting diodes (QD‐LEDs) were made based on hydrophilic CdTe quantum dots (QDs). A quantum dot‐inorganic nanocomposite (hydrophilic CdTe QDs incorporating dehydrated silica gel) was prepared by two methods (rotary evaporation and freeze drying). Taking advantage of its viscosity, plasticity and transparency, dehydrated silica gel could be coated on the surface of ultraviolet (UV) light LEDs to make photoluminescence QD‐LEDs. This new photoluminescence QD‐LED, which is stable, environmentally non‐toxic, easy to operate and low cost, could expand the applications of hydrophilic CdTe QDs in photoluminescence. Copyright © 2015 John Wiley & Sons, Ltd.     

Temporal response and attraction of Diaphorina citri to visual stimuli

As the vector of the global disease of citrus greening or huanglongbing, Asian citrus pysllids, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are the greatest threat to the worldwide citrus industry. Critical to management of D. citri and huanglongbing is optimization of surveillance methodologies. Although phytophagous insects may find host plants by multimodal cues, some appear to primarily use visual cues. In this study, we examined the behavior of Asian citrus psyllids toward light from light‐emitting diodes (LEDs) in the insect visible spectrum. The periodicity of attraction of psyllids to visual cues was evaluated in the field (yellow sticky traps) and laboratory (multi‐colored LEDs) with a strong peak of activity during the afternoon in both the field and the laboratory (both 14:00 to 18:00 hours). In laboratory evaluations of psyllids to differently colored LEDs, strongest attraction was to LEDs emitting ultraviolet (390 nm), green (525 nm), and yellow (590 nm) light. Male and female psyllids did not differ significantly in their responses to visual cues. These findings provide the basis for formulating better traps that reflect UV and yellow light and potentially incorporate UV LEDs for monitoring psyllids and a better understanding of Asian citrus psyllid visual behavior.