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Testing of Various Monochromatic LED Lights Used in Supplemental Irradiation of Lettuce in Modern Urban Rooftop Polytunnels
摘要： Urban farming could provide both vegetable growers and urban dwellers with more direct access to various fresh vegetables. Nevertheless, certain challenging problems associated with urban farming, including a lack of cultivation space and the effects of urban heat islands, must still be solved. Relatedly, a grower must, in some cases, also know how to utilize various forms of technology, such as lighting systems, as well as factors such as water availability. In this study, an original rooftop polytunnel design for lettuce (Lactuca sativa cv. Lollo Rosso) cultivation equipped with a hydroponic system and light emitting diodes (LEDs) is proposed. Various monochromatic lights were also tested for their effects on different quality parameters of lettuce. Specifically, supplemental red (655 nm), blue (445 nm), green (520 nm), and ultraviolet (380 nm) LED lights were used at night to apply photon fluxes of 150, 150, 150, and 20 μmol·m-2·s-1, respectively. The resulting effects of these different colored LEDs on the pigment concentration and growth response of the lettuce grown inside the roof polytunnel were then investigated. The experiment was then repeated several times with different environmental parameters in order to compare the effects of the different light wavelengths under higher temperatures and higher natural irradiation conditions. The results indicated that supplemental red or blue light at night could be strategically employed to maintain low nitrate levels and enhance the nutritional value and growth of lettuce grown in roof polytunnels.
关键词： Red lettuce,Rooftop polytunnel,Hydroponic,LEDs,Urban agriculture,Light emitting-diodes
更新于2025-09-23 15:21:01
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[IEEE 2019 19th International Conference on Control, Automation and Systems (ICCAS) - Jeju, Korea (South) (2019.10.15-2019.10.18)] 2019 19th International Conference on Control, Automation and Systems (ICCAS) - Relationship between LED Energy Consumption and Plant Growth in Small Hydroponic Plant Cultivation System
摘要： Global population growth and the ongoing climate crisis pose immense risk to the stable food supplies in the future. We have developed a small hydroponic plant cultivation system to ensure even in extreme circumstances. To build a sustainable system, we have utilized an LED lighting system together with conserved energy generated by sunlight. Such hydroponic plant cultivation systems have to operate at an affordable yet efficient principle. In this paper, we examine experimental results of the relationship between LED energy consumption and plant growth in a hydroponic plant cultivation system. LED light intensity directly correlates to electrical power consumed. Energy consumption is the result of electrical power consumed over a period of time. Three experiments with varying conditions utilizing constant electrical energy consumption were conducted. Case-1: Electric power is kept low and the lighting duration is long; Case-2: the electric power is set to medium and the lighting duration is medium; Case-3: the electric power is large and the lighting duration is short. As a result of evaluating the weight of grown lettuces, it was found that lettuce growth is excellent in Case-1. It means that the longer the LED irradiation duration, the better the plant growth even under the same energy consumption conditions.
关键词： Lighting duration,LEDs,Leaf lettuce growth,Energy consumption,Indoor hydroponic system
更新于2025-09-23 15:19:57
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Differential effects of high light duration on growth, nutritional quality, and oxidative stress of hydroponic lettuce under red and blue LED irradiation
摘要： In this study, effects of high light irradiation (HLI, 500 μmol m?2·s?1) duration in the middle of light period (16 h, 150 μmol m?2·s?1) provided by red (R) and blue (B) LEDs (4R:1B) on the growth, nutritional quality, and oxidative stress of hydroponic purple leaf lettuce grown in an environmentally controlled plant factory were examined on the 10th and 20th day after treatment. Set up five treatments with 0 h (CK), 0.5 h (HL0.5), 1 h (HL1), 2 h (HL2), and 4 h (HL4) HLI, respectively. We found that the shoot fresh weight of lettuce increased first and then decreased with the prolongation of HLI duration, whether in the early or late growth stage. On the 10th day after treatment, the root fresh weight and specific leaf weight of lettuce increased linearly with the prolongation of HLI duration, while the shoot/root ratio decreased linearly. On the 20th day after treatment, the lettuce of HL1 had the highest shoot fresh weight, leaf area, and shoot dry weight, followed by HL2. Besides, HL4 promoted the accumulation of soluble sugar, anthocyanin, flavonoid, and total phenolic simultaneously decreased the maximum quantum efficiency compared with others on the 10th day after treatment. On the 20th day after treatment, HL0.5 and HL4 stimulated the accumulation anthocyanin, flavonoid, total phenolic, and ascorbic acid compared with other treatments. The results showed that short-term HLI promotes biomass production and secondary metabolite accumulation, but HL4 caused photo-oxidative damage to lettuce. Therefore, lettuce growth and qualities can be purposely adjusted by adopting different duration of HLI provided by red and blue light in the plant factory, also these responses depended on lettuce growth stage closely.
关键词： Secondary metabolite accumulation,Hydroponic lettuce,High light irradiation,Antioxidant,LED
更新于2025-09-23 15:19:57