Light-emitting diodes׳ light qualities and their corresponding scientific applications

Yeh, Naichia; Ding, Tao; Yeh, Pulin

doi:10.1016/j.rser.2015.04.177

Cited by 54 publications

(33 citation statements)

References 64 publications

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“…In recent years, an increasing number of supplementary light technology using light emitting diodes (LEDs) has been used in agricultural production [17][18][19][20]. The improvement in the growth, yield, and quality of crops has been confirmed by many studies [6,[21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

2020

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Insufficient exposure to light in the winter may result in a longer production periods and lower quality of seedlings in greenhouses for plug growers. Supplementary artificial lighting to plug seedlings may be one solution to this problem. The objective of this study was to assess the effects of the duration of the supplementary light on the growth and development of two watermelon cultivars, ‘Speed’ and ‘Sambok Honey’ grafted onto ‘RS-Dongjanggun’ bottle gourd rootstocks (Lagenaria siceraria Stanld). Seedlings were grown for 10 days in a glasshouse with an average daily natural light intensity of 340 μmol·m−2·s−1 photosynthetic photon flux density (PPFD) and daily supplementary lighting of 8, 12 or 16 h from mixed LEDs (W1R2B1, chip ratio of white:red:blue = 1:2:1) at a light intensity of 100 μmol·m−2·s−1 PPFD, a group without supplementary light was set as the control (CK). The culture environment in a glasshouse had 25/15 °C day/night temperatures, an 85 ± 5% relative humidity, and a natural photoperiod of 8 h. The results showed that all the growth and development parameters of seedlings grown with supplementary light were significantly greater than those without supplementary light (CK). The 12 and 16 h supplementary light resulted in greater growth and development parameters than the 8 h supplementary light did. The same trend was also found with the indexes that reflect the quality of the seedlings, such as the dry weight ratio of the shoot and root, total biomass, dry weight to height ratio of scions, and specific leaf weight. The 12 h and 16 h light supplements resulted in greater Dickson’s quality indexes compared to the 8 h supplementary light, and the 12 h supplementary light showed the greatest use efficiency of the supplementary light. 16 h of daily supplementary light significantly increased the H2O2 content and the antioxidant enzyme activities in seedlings compared to the other treatments. This indicated that 16 h of supplementary light led to certain stresses in watermelon seedlings. In conclusion, considering the energy consumption, 12 h of supplementary light was the most efficient in improving the quality of the two cultivars of grafted watermelon plug seedlings.

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Section: Introductionmentioning

confidence: 99%

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

2020

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“…It has been reported that blue light with the wavelength of 410-500 nm affects the growth of chlorophyll, leaf morphogenesis, ower-bud formation, stomatal opening, and phototropism, and red light with the wavelength of 610-700 nm may be supportive to develop the vegetative owering, budding, and internodal elongation, while the far-red light around 730 nm promotes the plant cultivation and photosynthesis. [19][20][21][22] Hence, it is essential to nd alternative high colour purity red or deep red emitting phosphors.…”

Section: Introductionmentioning

confidence: 99%

Novel SrLaAlO₄:Mn⁴⁺deep-red emitting phosphors with excellent responsiveness to phytochrome P_FRfor plant cultivation LEDs: synthesis, photoluminescence properties, and thermal stability

et al. 2018

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Herein, novel rare-earth-free Mn 4+ -doped SrLaAlO 4 deep-red emitting phosphors were successfully synthesized via a traditional solid-state reaction method. The crystal structure and phase purity of the asprepared samples were confirmed by XRD Rietveld refinement. Photoluminescence properties of SrLaAlO 4 :Mn 4+ phosphors were examined in detail using photoluminescence spectra, decay lifetimes, temperature-dependent emission spectra and internal quantum efficiency measurements. The excitation spectrum obtained by monitoring at 730 nm contained two excitation bands centered at 364 and 520 nm within the range of 200-550 nm due to the Mn 4+ -O 2À charge-transfer band and the 4 A 2g / 4 T 1g , 4 T 2g transitions of the Mn 4+ ions. Under the 364 nm excitation, the SrLaAlO 4 :Mn 4+ phosphors exhibited an intense deep-red emission band in 610-790 nm wavelength range peaking at 730 nm,which was assigned to the 2 E g / 4 A 2g transition of Mn 4+ ions. The deep red emission showed excellent responsiveness to phytochrome P FR , revealing that the SrLaAlO 4 :0.4% Mn 4+ phosphors possessed a possible application in deep-red light-emitting diodes (LEDs) for plant cultivation. The optimal doping concentration of Mn 4+ ions was found to be 0.4 mol%. The critical distance R c for energy transfer among Mn 4+ ions was determined to be 5.86Å and the concentration quenching mechanism was confirmed to be the electric dipole-dipole interaction. In addition, the Commission International de I'Eclairage (CIE) colour coordinates of the SrLaAlO 4 :0.4% Mn 4+ phosphors (0.734, 0.266) were located in the deep red region and the corresponding internal quantum efficiency was measured to be about 29%.The above results confirmed that the as-prepared SrLaAlO 4 :0.4% Mn 4+ deep red emitting phosphors might be a potential candidate for plant cultivation LEDs.

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“…The main advantage LED has over traditional devices is its high durablility, with a life expectancy of approximately 30,000 h, and consumes low energy when producing a high luminous flux. In the visible light spectrum, due to its safety, it does not require additional protection of its operator (Ghate et al, 2013;Yeh et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Using light emitting diodes at 450 nm for in vitro treatment of water intended for human consumption

Felipe¹,

Juciene²,

Ana³

et al. 2018

Afr. J. Microbiol. Res.

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This study aimed to evaluate the in vitro antimicrobial effect of exposing raw water intended for human consumption to light (λ= 450 nm) and to investigate the correlation between the results obtained and physical and chemical parameters. Fifteen (15) samples of raw water were collected from households in a rural area of Santo Antônio de Jesus -Bahia (Brazil), from November to December 2016. A 100 mL aliquot of each sample was exposed to a lighting system consisting of two high intensity light emitting diodes, with a wavelength of 450 nm and luminous flux of 200 lumens per 10 h. Quantifications of heterotrophic bacteria, total coliforms and temperature started at time zero and were done every two hours until the end of exposure to light. Bacteriological analysis was repeated after 72 h of being exposed to light. pH, dissolved oxygen and salinity analyses were performed before each experiment. After a 10h illumination at 450 nm light emitting diodes (LEDs), the dosage of light received by the water samples was 581.8 J/cm 2 . There was a significant reduction in the two bacteriological parameters analyzed after treatment (p = 0.000). There was an average decrease in heterotrophic bacteria counts from 3.44 to 1.86 log CFU/mL and total coliforms from 2.45 to 1.02 log CFU/mL. Mean reductions of heterotrophic bacteria were 97.01% and total coliforms were 95.61%. After 72 h, both counts increased; there was significant growth between heterotrophic bacteria (p = 0.000), but there was no significant growth for total coliforms (p = 0.058). pH (p = -0.981, p = 0.000), dissolved oxygen (ρ = -0.529, p = 0.043) and temperature (ρ = 0.521, p = 0.047) were related to the percentage reduction of heterotrophic bacteria. The method is shown to be effective in disinfecting raw water in vitro under different physical and chemical conditions.

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Light-emitting diodes׳ light qualities and their corresponding scientific applications

Cited by 54 publications

References 64 publications

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

Novel SrLaAlO₄:Mn⁴⁺deep-red emitting phosphors with excellent responsiveness to phytochrome P_FRfor plant cultivation LEDs: synthesis, photoluminescence properties, and thermal stability

Using light emitting diodes at 450 nm for in vitro treatment of water intended for human consumption

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Light-emitting diodes׳ light qualities and their corresponding scientific applications

Cited by 54 publications

References 64 publications

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

Novel SrLaAlO4:Mn4+deep-red emitting phosphors with excellent responsiveness to phytochrome PFRfor plant cultivation LEDs: synthesis, photoluminescence properties, and thermal stability

Using light emitting diodes at 450 nm for in vitro treatment of water intended for human consumption

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Novel SrLaAlO₄:Mn⁴⁺deep-red emitting phosphors with excellent responsiveness to phytochrome P_FRfor plant cultivation LEDs: synthesis, photoluminescence properties, and thermal stability