scholarly journals Continuous Irradiation with Alternating Red and Blue Light Enhances Plant Growth While Keeping Nutritional Quality in Lettuce

HortScience ◽  
2018 ◽  
Vol 53 (12) ◽  
pp. 1804-1809 ◽  
Author(s):  
Noriko Ohtake ◽  
Masaharu Ishikura ◽  
Hiroshi Suzuki ◽  
Wataru Yamori ◽  
Eiji Goto
Keyword(s):  
Plant Growth ◽  
Leaf Area ◽  
Blue Light ◽  
Nutritional Quality ◽  
Continuous Irradiation ◽  
Light Emitting ◽  
Artificial Lighting ◽  
Fluorescent Lamps ◽  
High Concentrations ◽  
Net Assimilation

Plant factories with artificial lighting have been developed to improve food production, functional ingredients, and profitability. Intensive research has been performed to elucidate the effects of light intensity and wavelength on plant growth and nutritional quality with the use of light-emitting diodes (LEDs). In particular, the effects of monochromatic red, blue, or simultaneous red + blue light have been studied because these wavelengths are predominantly used for photosynthesis. We examined the effects of alternating red and blue light provided by LEDs over a period of 24 hours on the growth and nutritional properties of leafy lettuce. The results clearly show that alternating red and blue light accelerated plant growth significantly compared with white fluorescent lamps or red and blue LEDs at the same daily light integral. Plants grown under alternating red/blue light had a greater net assimilation rate and total and projected leaf area (an indicator of the fraction of leaf area that absorbs more light) than other plants. Additionally, alternating red and blue light maintained high concentrations of sugars, ascorbic acid, and anthocyanins in leaves. Taken together, the results indicate that continuous irradiation with alternating red and blue light could enhance growth while maintaining the nutritional quality in lettuce.

scholarly journals Green-light Supplementation for Enhanced Lettuce Growth under Red- and Blue-light-emitting Diodes

HortScience ◽  
2004 ◽  
Vol 39 (7) ◽  
pp. 1617-1622 ◽  
Author(s):  
Hyeon-Hye Kim ◽  
Gregory D. Goins ◽  
Raymond M. Wheeler ◽  
John C. Sager
Keyword(s):  
Plant Growth ◽  
Light Source ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Light Sources ◽  
Natural Setting ◽  
Light Emitting ◽  
Fluorescent Lamps ◽  
Green Fluorescent

Plants will be an important component of future long-term space missions. Lighting systems for growing plants will need to be lightweight, reliable, and durable, and light-emitting diodes (LEDs) have these characteristics. Previous studies demonstrated that the combination of red and blue light was an effective light source for several crops. Yet the appearance of plants under red and blue lighting is purplish gray making visual assessment of any problems difficult. The addition of green light would make the plant leave appear green and normal similar to a natural setting under white light and may also offer a psychological benefit to the crew. Green supplemental lighting could also offer benefits, since green light can better penetrate the plant canopy and potentially increase plant growth by increasing photosynthesis from the leaves in the lower canopy. In this study, four light sources were tested: 1) red and blue LEDs (RB), 2) red and blue LEDs with green fluorescent lamps (RGB), 3) green fluorescent lamps (GF), and 4) cool-white fluorescent lamps (CWF), that provided 0%, 24%, 86%, and 51% of the total PPF in the green region of the spectrum, respectively. The addition of 24% green light (500 to 600 nm) to red and blue LEDs (RGB treatment) enhanced plant growth. The RGB treatment plants produced more biomass than the plants grown under the cool-white fluorescent lamps (CWF treatment), a commonly tested light source used as a broad-spectrum control.

scholarly journals Lettuce Growth, Nutritional Quality, and Energy Use Efficiency as Affected by Red–Blue Light Combined with Different Monochromatic Wavelengths

HortScience ◽  
2020 ◽  
Vol 55 (5) ◽  
pp. 613-620 ◽  
Author(s):  
Lie Li ◽  
Yu-xin Tong ◽  
Jun-ling Lu ◽  
Yang-mei Li ◽  
Qi-chang Yang
Keyword(s):  
Plant Growth ◽  
Leaf Area ◽  
Blue Light ◽  
Nutritional Quality ◽  
Energy Use ◽  
Carotenoid Content ◽  
Photon Flux ◽  
Energy Use Efficiency ◽  
Lettuce Growth ◽  
Use Efficiency

Light, as the energy and signal sources for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFALs). To find the optimal combination of light wavelengths for lettuce (Lactuca sativa cv. ‘Tiberius’) plant growth in a PFAL, four treatments, each using red (R; 662 nm) and blue light (B; 447 nm) with a ratio of 4:1 and photon flux density (PFD) of 150 μmol·m−2·s−1, and mixing, respectively, with 50 μmol·m−2·s−1 of green light (G; 525 nm; RBG), yellow light (Y; 592 nm; RBY), orange light (O; 605 nm; RBO) and far-red light (FR; 742 nm; RBFR), were set up during this experiment. A combination of R and B with a ratio of 4:1 and PFD of 200 μmol·m−2·s−1 was set as the control (RB). The responses of lettuce growth, morphology, anatomical structure of the lettuce leaf, photosynthetic performance, lettuce nutritional quality, and energy use efficiency were investigated. The results showed that RBG, RBO, and RBFR increased the shoot fresh weight of lettuce by 20.5%, 19.6%, and 40.4%, and they increased the shoot dry weight of lettuce by 24.2%, 13.4%, and 45.2%, respectively, compared with those under RB. The Pn under RBY was significantly lower than that under RB, although no significant differences in chlorophyll or carotenoid content were found between RBY and RB. RBG increased the lettuce leaf area, the thickness of the leaf palisade tissue, Pn, and light use efficiency compared with those under RB. Plants grown under RBO showed better photosynthetic capacity, such as higher Pn, ΦPSII, and other photosynthetic parameters. RBFR caused an increase in lettuce leaf area and energy use efficiency, but a decrease in leaf thickness and Pn of the single leaf. Moreover, tipburn injury was observed under RBFR. Therefore, these results demonstrate that RBG and RBO can be considered optimal combinations of light wavelengths for lettuce growth in a PFAL in this experiment, although plant growth can also be improved by using RBFR.

Quality and Intensity of Light in the In Vitro Development of Microstumps of Eucalyptus urophylla in a Photoautotrophic System

2020 ◽  
Vol 66 (6) ◽  
pp. 754-760 ◽  
Author(s):  
Natane A Miranda ◽  
Aloisio Xavier ◽  
Wagner C Otoni ◽  
Ricardo Gallo ◽  
Kellen C Gatti ◽  
...  
Keyword(s):  
Plant Growth ◽  
Light Quality ◽  
Stomatal Density ◽  
Carotenoid Content ◽  
Fluorescent Light ◽  
Eucalyptus Urophylla ◽  
Light Emitting ◽  
Fluorescent Lamps ◽  
Number Of Shoots

Abstract The quality and quantity of light are important factors in controlling in vitro plant growth in photoautotrophic systems. The aim of this study was to evaluate the influence of light quality (fluorescent, white, red, blue, red/blue, and distant red) on microstumps of a Eucalyptus urophylla clone in an in vitro photoautotrophic system, as well as the intensity of fluorescent light (60, 85, 100, and 140 μmol m–2 s–1) in the growth and production of microcutting. The number of shoots and microcutting, the size of the largest shoot, the stomatal density, chlorophyll, and carotenoid content were analyzed. Light quality altered plant growth, and fluorescent light intensity did not affect the microstumps’ production during the evaluation period. In white light-emitting diode (LED) light, there was higher production of carotenoids, with a lower initial production of microcuttings. A smaller number of shoots were obtained in blue LED. In general, the different qualities and light intensities tested allowed for the growth of the Eucalyptus urophylla clone grown in vitro, making it possible to obtain microcuttings under photoautotrophic cultivation. Study Implications In vitro propagation is a stressful process for plants and has limitations for commercial-scale Eucalyptus production. Fluorescent lamps, closed containers, and high sucrose concentrations are traditionally used. To reduce costs and improve production, the use of efficient light sources and photoautotrophic cultivation systems become alternatives. This study investigated the influence of light on the in vitro growth of a Eucalyptus clone in a photoautotrophic system. The quality was more important than the intensity of light. Foresters will be able to indicate the use of LEDs (light-emitting diodes) as a replacement for fluorescent lamps. This approach is useful in enhancing micropropagation techniques.

scholarly journals Effects of Daily Light Integral and LED Spectrum on Growth and Nutritional Quality of Hydroponic Spinach

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1082 ◽  
Author(s):  
Wei Gao ◽  
Dongxian He ◽  
Fang Ji ◽  
Sen Zhang ◽  
Jianfeng Zheng
Keyword(s):  
Vitamin C ◽  
Blue Light ◽  
Nutritional Quality ◽  
Red Light ◽  
Nitrate Content ◽  
Energy Yield ◽  
Daily Light Integral ◽  
Fluorescent Lamps ◽  
Plant Factory ◽  
Light Integral

To achieve clean and high-quality spinach production, the effects of daily light integral (DLI) and light spectrum on growth, nutritional quality, and energy yield of hydroponic spinach (Spinacia oleracea L.) were investigated in a closed plant factory under light-emitting diode (LED) lighting. The hydroponic spinach plants were grown under 16 combinations of four levels of DLI (11.5, 14.4, 17.3, and 20.2 mol m−2 day−1) with four light spectra: LED lamps with ratio of red light to blue light (R:B ratio) of 0.9, 1.2, and 2.2 and fluorescent lamps with R:B ratio of 1.8 as control. The results show that total fresh and dry weights, energy yield, and light energy use efficiency (LUE) of harvested spinach were higher under D17.3-L1.2 treatment compared to other treatments. The higher net photosynthetic rates were shown at DLI of 17.3 mol m−2 day−1 regardless of light quality. Higher vitamin C contents of spinach in all LED treatments were obtained compared with the control. L1.2 treatments with higher fraction of blue light led to more vitamin C content, lower nitrate content, and higher LUE independent of DLI. L2.2 treatment with more fraction of red light was beneficial to reduce oxalate accumulation. Power consumption based on increased total fresh weight under LED lamps with R:B ratio of 1.2 in different DLIs was over 38% lower than that under the fluorescent lamps and 1.73 kWh per 100 g FW at DLI of 17.3 mol m−2 day−1. In conclusion, lighting environment in DLI of 17.3 mol m−2 day−1 using LED lamps with R:B ratio of 1.2 is suggested for the design of a LED plant factory for hydroponic spinach production.

Banana plant growth. 2. Dry matter production, leaf area and growth analysis

1972 ◽  
Vol 12 (55) ◽  
pp. 216 ◽  
Author(s):  
DW Turner
Keyword(s):  
Plant Growth ◽  
Leaf Area ◽  
Dry Matter ◽  
Early Summer ◽  
Growth Stages ◽  
Assimilation Rate ◽  
Banana Plant ◽  
Area Index ◽  
Net Assimilation ◽  
Plant Crop

The quantitative aspects of banana plant growth (omitting roots) at Alstonville, New South Wales, are described. Dry matter distribution, leaf area index (L), net assimilation rate (E), leaf area ratio (F) and relative growth rates (R), were measured. For a spring planting, only 1695 kg ha-l dry matter were produced in the first twelve months but 6780 kg were produced in the first half of the second year as the bunch and first ratoon crop developed. The plant crop was characterized by early leaf growth (high F) whereas in the ratoon crops, corm growth was a feature of early growth stages. Leaf area index was less than 1 for the first twelve months but reached 5 after 18 months. Plants were 3.1 m X 1.9 m apart. Net assimilation rate was affected by internal and external factors. The main internal control was the growth of suckers, which tended to increase E. Removal of the suckers in autumn or winter caused a sudden drop i i ~ E and absolute growth rate but when they were removed in early summer E was increased. The external controls affecting E were solar radiation, temperature and soil moisture, although the amount of variation explained in correlations was low. - R appeared to be constant in the plant crop within morphologically defined growth stages. This was not so in moon crops and R was probably a resultant of ontogenetic and climatic drifts. Desuckering in autumn and winter decreased R. Early summer desuckering increased R.

scholarly journals A dual-emitting core–shell carbon dot–silica–phosphor composite for LED plant grow light

RSC Advances ◽  
2017 ◽  
Vol 7 (27) ◽  
pp. 16662-16667 ◽  
Author(s):  
Li Wang ◽  
Haoran Zhang ◽  
Xiaohua Zhou ◽  
Yingliang Liu ◽  
Bingfu Lei
Keyword(s):  
Disease Prevention ◽  
Plant Growth ◽  
Light Emitting Diodes ◽  
Core Shell ◽  
Carbon Dot ◽  
Light Emitting ◽  
Artificial Lighting

Light-emitting diodes (LEDs) are widely used for artificial lighting in plant factories and have been applied for disease prevention and for accelerating plant growth.

scholarly journals Dissecting the Genotypic Variation of Growth Responses to Far-Red Radiation in Tomato

2021 ◽  
Vol 11 ◽  
Author(s):  
Yongran Ji ◽  
Theoharis Ouzounis ◽  
Henk J. Schouten ◽  
Richard G. F. Visser ◽  
Leo F. M. Marcelis ◽  
...  
Keyword(s):  
Leaf Area ◽  
Genotypic Variation ◽  
Dry Mass ◽  
Growth Responses ◽  
Light Emitting ◽  
Red Led ◽  
Total Plant ◽  
Net Assimilation ◽  
Tomato Genotypes ◽  
Plant Dry Mass

The recent development of light-emitting diodes (LEDs) and their application in modern horticulture stimulated studies demonstrating that additional far-red (FR) radiation (700–800 nm) increases plant dry mass. This effect of FR has been explained by improved photosynthesis and/or plant architecture. However, the genotypic variation in this response is largely unknown. Here, we aim to explore and explain the genotypic variation in growth responses to additional FR. We expected the genotypic variation in the responses of plant dry mass to additional FR. Further, we hypothesized that a significant improvement of both net assimilation rate (NAR) and leaf area ratio (LAR) is responsible for a strong dry mass increase under additional FR, while some genotypes respond only marginally or even negatively in NAR or LAR under FR, thus resulting in a weak FR effect on plant dry mass. To test these hypotheses, we grew 33 different tomato genotypes for 21 days with 0, 25, or 100 μmol m–2 s–1 of FR added to a common white + red LED background lighting of 150 μmol m–2 s–1. Genotypes responded similarly with respect to plant height, stem dry mass, and shoot:root ratio; i.e., they all increased with increasing FR. However, the response of total plant dry mass varied among genotypes. We categorized the genotypes into three groups (strongly, moderately, and weakly responding groups) based on their relative response in total plant dry mass to FR. Growth component analysis revealed that the strongly responding genotypes increased strongly in NAR rather than LAR. The weakly responding genotypes, however, showed a substantial increase in LAR but not NAR. The increase in LAR was due to the increase in specific leaf area. Leaf mass fraction, which is the other component of LAR, decreased with FR and did not differ between groups. In conclusion, tomato genotypes that increased strongly in NAR in response to FR were able to achieve a more substantial increase in dry mass than did other genotypes. This is the first study to explain the differences in growth responses of a large number of tomato genotypes toward FR in their light environment.

scholarly journals Effects of Frequency and Duty Ratio on the Growth of Potato Plantlets In Vitro Using Light-emitting Diodes

HortScience ◽  
2004 ◽  
Vol 39 (2) ◽  
pp. 375-379 ◽  
Author(s):  
Ruey-Chi Jao ◽  
Wei Fang
Keyword(s):  
Plant Growth ◽  
Light Emitting Diodes ◽  
Heat Removal ◽  
Duty Ratio ◽  
Intermittent Light ◽  
Light Emitting ◽  
Fluorescent Lamps ◽  
Fluctuating Light ◽  
Potato Plantlets

Effects of intermittent light on photomixotrophic growth of potato plantlets in vitro and the electrical savings that could be realized by adjusting the frequency and duty ratio of light-emitting diodes (LEDs) were investigated and compared to the use of conventional tubular fluorescent lamps (TFLs). TFLs provide continuous fluctuating light at 60 Hz and LEDs provide continuous nonfluctuating or intermittent/pulse light depend on the preset frequency and duty ratio. In total, eight treatments were investigated with varying light source, frequency, duty ratio and photoperiod. Results indicated that if growth rate is the only concern, LEDs at 720 Hz [1.4 milliseconds (ms)] and 50% duty ratio with 16-h light/8-h dark photoperiod stimulated plant growth the most. However, if energy consumption is the major concern, using LEDs at 180 Hz (5.5 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod would be the best choice for illuminating potato plantlets without significantly sacrificing plant growth, especially when energy for heat removal is also considered.

scholarly journals Effect of the Spectral Quality and Intensity of Light-emitting Diodes on Several Horticultural Crops

HortScience ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 268-271 ◽  
Author(s):  
Miguel Urrestarazu ◽  
Cinthia Nájera ◽  
María del Mar Gea
Keyword(s):  
Plant Growth ◽  
Light Emitting Diode ◽  
Photon Flux ◽  
Photosynthetic Response ◽  
Light Spectrum ◽  
Light Emitting ◽  
Artificial Lighting ◽  
Horticultural Crops ◽  
Distribution Study ◽  
Environment Chamber

Light-emitting diode (LED) lamps signify one of the most important advances in artificial lighting for horticulture over the last few decades. The objective of this study was to compare the cultivation of four horticultural plants using a conventional white LED tube (T0) light against one with a good spectral fit to the maximum photosynthetic response (T1) at two intensities. The experiment was carried out with two types of young lettuce, tomato, and bell pepper plants. In a controlled environment chamber, six and four lamps per square meter were used to achieve high (H) and low (L) intensity, respectively. We measured the lighting parameters illuminance (lux) and photosynthetic photon flux (PPF) intensity (µmol·m−2·s−1). The dry and fresh weight, leaf area (LA), and specific index were measured to gauge plant growth. The photosynthetic activity and energy efficiency (EE) were recorded for each species over 60 days of cultivation. The results clearly demonstrate that, compared with conventional LED lamps, the specific horticultural LED lamps with an improved light spectrum increased the EE of the evaluated vegetables by 26%. At both the studied light intensities, plant growth was clearly more closely linked to the spectral fit of the light to the maximum photosynthetic response recorded by McCree (1972) than to PPF or illuminance (lux). We therefore suggest that a specific, detailed spectral distribution study be conducted to predict the effect of the specific quantity and quality of light used in this study on a single parameter of plant growth.

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