Various light quality including QD-LED affect growth and leaf color of red romaine baby leaf lettuce (original) (raw)
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International Journal of Environment, Agriculture and Biotechnology
Indoor culture requires a variety of inputs to get maximum biomass. These inputs are the nutrients, temperature, humidity, and light which plants needed to photosynthesize. Different types of light have been studied and it is known that the same spectrum will give different responses by different plants. The purpose of this study was to find out the effect of red-blue-white light LED on lettuce growth compared to grow light LED as a control which commonly used in plant factory rooms. The red-blue-white light is arranged on a 100 cm long aluminum rod, mounted along the plant in a gully DFT hydroponic fed by 1000-2000 ppm nutrients of ABmix plus with a pH of 5.5-6.5. LED grow light provided the plant a significantly higher height of 16.30% compared to red-blue-white light, but was no different to the length of lettuce root. The number and the area of leaves in red-blue-white light were markedly higher at 16.67% and 33.78% respectively than grow light. In addition, the red-blue-white l...
2014
Because global climate change has made agricultural supply unstable, plant factories are expected to be a safe and stable means of food production. As the light source of a plant factory or controlled greenhouse, the light emitting diode (LED) is expected to solve cost problems and promote plant growth efficiently. In this study, we examined the light condition created by using monochromatic red and blue LEDs, to provide both simultaneous and alternating irradiation to leaf lettuce. The result was that simultaneous red and blue irradiation promoted plant growth more effectively than monochromatic and fluorescent light irradiation. Moreover, alternating red and blue light accelerated plant growth significantly even when the total light intensity per day was the same as with simultaneous irradiation. The fresh weight in altering irradiation was almost two times higher than with fluorescent light and about 1.6 times higher than with simultaneous irradiation. The growth-promoting effect...
Horticulturae, 2022
Plant factories using artificial light to produce vegetables have high energy costs due to the high demand for electricity for lighting. Compared to conventional light sources, light-emitting diodes (LEDs) offer the possibility of tailoring the light spectrum and regulating light intensity and are more energy-efficient in terms of energy conversion regardless of the levels of lighting intensity. Optimal light intensity and daily light integral (DLI) requirements are key factors for plant growth; however, their values vary among species and varieties. Our experiment aimed to identify the best light intensity to produce lettuce plants in controlled environment. Lettuce plants of the type Batavia cv ‘Blackhawk’ were grown in plastic pots filled with perlite and peat (20:80 v/v) for 33 days in a growth chamber under blue (B, 20%) and red (R, 80%) LED light at a photosynthetic flux density of 130 µmol m−2 s−1 (BR 130, DLI 7.49 mol m−2 d−1), 259 µmol m−2 s−1 (BR 259, DLI 14.92 mol m−2 d−1...
Frontiers in Plant Science, 2021
The challenges of feeding an increasing population, an increasingly urban population and within an increasingly challenging global environment have focused ideas on new ways to grow food. Growing food in a controlled environment (CE) is not new but new technologies such as broad-spectrum LEDs and robotics are generating new opportunities. Growth recipes can be tailored to plant species in a CE and plasticity in plant responses to the environment may be utilized to make growth systems more efficient for improved yield and crop quality. Light use efficiency within CE must consider energy requirements, yield and impacts on quality. We hypothesized that understanding how plants change their morphology and physiology in response to light will allow us to identify routes to make light more efficient for delivery of high-quality produce. We focused on responses to light in Lollo rosso lettuce which produces compact, crinkly and highly pigmented leaves. We compared the spectra of the commonly used artificial light sources in indoor farming (compact fluorescence tubes, FL, and broad-spectrum light-emitting diodes, LEDs) at two irradiance levels (270 and 570 µmol m −2 s −1). We discovered LEDs (λ P : 451, 634, and 665 nm) produced the same amount of produce for half the incident energy of FL (T5). At higher irradiances LEDs produced 9% thicker leaves, 13% larger rosettes and 15% greater carotenoid content. Leaves differed in light absorptance with plants grown under lower FL absorbing 30% less of mid-range wavelengths. We show that the relative efficiencies of LED and FL is a function of the irradiances compared and demonstrate the importance of understanding the asymptotes of yield and quality traits. Increasing our understanding of structural and biochemical changes that occur under different combination of wavelengths may allow us to better optimize light delivery, select for different ranges of plasticity in crop plants and further optimize light recipes.
Archives of Agriculture and Environmental Science , 2024
This study investigated how LED light exposure influences the growth and nutrient content of two lettuce microgreens over 10 days in a randomized setup. Lettuce seeds underwent surface sterilization, germination in prepared soil, and exposure to different LED light conditions. Morphological parameters and pigment analysis, including stem length, petiole length, leaf area, plant height, root length, fresh weight, dry matter percentage, were evaluated. Green lettuce outperformed red lettuce in the studied morphological parameters, including stem length (2.74±0.22 cm), plant height (4.54±0.21 cm), and fresh weight (3.79±0.32 g/100 plants) under different LED. White light promoted taller plants with higher fresh weight (4.45±0.43 g/100plants), dry matter (4.84±0.38%), and leaf area (0.76±0.06 cm 2) in both lettuce species. In contrast, red light reduced overall growth and development, as evidenced by a 54% decrease in leaf area, despite a 23.36% increase in plant height. Chlorophyll levels varied significantly among LED treatments, with white LED yielding the highest levels in both red and green lettuce. Highest chlorophyll a (146.37±6.27 µg/g FW), chlorophyll b (86.74±2.44 µg/g FW), total chlorophyll (233.11±8.69 µg/g FW) and relative chlorophyll (215.84±8.05 µg/cm²) content was found in green lettuce under white light condition. Similarly, green lettuce grown under white LED had the highest total carotenoid, β-carotene, and lutein. The study concludes that optimizing white LED illumination has the potential to improve the nutritional value of lettuce microgreens by enhancing growth and pigment content, particularly in green varieties. These findings emphasize the crucial role of LED light color in optimizing the nutritional quality of microgreens.
Journal of the Faculty of Agriculture, Kyushu University
This study discussed the influence of light-emitting diodes (LEDs) with red, blue, green, and yellow light on the growth and photosynthetic efficiency of Boston lettuce and Ziyan lettuce as a reference for lettuce production in plant factories. The experiments were conducted in a plant factory under a 120 µmole・m-2 ・s-1 photosynthetic photon flux density, CO 2 concentration of 1000 ppm, and daytime and nighttime temperature of 25°C/18 h and 17°C/6 h, respectively. The experiment results revealed that after 15 days of treatment under different spectral qualities, the appearances of the two lettuce leaves differed slightly. The fresh and dry weights of the Boston lettuce were highest under green light treatment. The fresh and dry weights of the Ziyan lettuce were higher under red and green light, and blue light helped the leaves to change color. In addition, photosynthesis analyzers were used to investigate the photosynthetic efficiency of the two types of lettuce under the four spectral qualities under the six luminous intensity levels of 20, 40, 60, 80, 100, and 120 µmole・m-2 ・s-1 and six CO 2 concentrations of 400, 600, 800, 1000, 1200, and 1400 ppm. The photosynthetic efficiency of the two types of lettuce generally increased with increasing luminous intensity and CO 2 concentration. When the luminous intensity was 100 and 120 µmole・m-2 ・s-1 and the CO 2 concentration was 1200 ppm and 1400 ppm, the Boston lettuce had the highest photosynthetic efficiency under green light. When luminous intensity was 120 µmole・m-2 ・s-1 and the CO 2 concentration was over 1000 ppm, the Ziyan lettuce had the highest photosynthetic efficiency under red light. These results revealed that the monochromatic LED light most suitable for growth differed across types of lettuce. In this experiment, the yield and photosynthetic efficiency of Boston lettuce were highest under green light. Those of Ziyan lettuce were highest under red light.
Plants
Controlled Environment Agriculture (CEA) is a method of increasing crop productivity per unit area of cultivated land by extending crop production into the vertical dimension and enabling year-round production. Light emitting diodes (LED) are frequently used as the source of light energy in CEA systems and light is commonly the limiting factor for production under CEA conditions. In the current study, the impact of different spectra was compared with the use of white LED light. The various spectra were white; white supplemented with ultraviolet b for a week before harvest; three combinations of red/blue lights (red 660 nm with blue 450 nm at 1:1 ratio; red 660 nm with blue 435 nm 1:1 ratio; red 660 nm with blue at mix of 450 nm and 435 nm 1:1 ratio); and red/blue supplemented with green and far red (B/R/G/FR, ratio: 1:1:0.07:0.64). The growth, yield, physiological and chemical profiles of two varieties of lettuce, Carmoli (red) and Locarno (green), responded differently to the vario...
Plants, 2019
The aim of this study was to investigate the different combinations of red (R) and blue (B) light emitting diode (LEDs’) lighting effects on growth, pigment content, and antioxidant capacity in lettuce, spinach, kale, basil, and pepper in a growth chamber. The growth chamber was equipped with R and B light percentages based on total light intensity: 83% R + 17% B; 91% R + 9% B; 95% R + 5% B; and control was 100% R. The photosynthetic photon flux density (PPFD), photoperiod, temperature, and relative humidity of the growth chamber were maintained at 200 ± 5 μmol m−2 s−1, 16 h, 25/21 ± 2.5 °C, and 65 ± 5%, respectively. It is observed that the plant height of lettuce, kale, and pepper was significantly increased under 100% R light, whereas the plant height of spinach and basil did not show any significant difference. The total leaf number of basil and pepper was significantly increased under the treatment of 95% R + 5% B light, while no significant difference was observed for other pl...
High intensity and red enriched LED lights increased growth of lettuce and endive
Italian Journal of Agronomy
Changes in plant responses have been associated with different fractions of the visible spectrum and light intensity. Advances in light emitting diodes (LED) have enabled the study of the effect of narrow wavelengths on plant growth and antioxidant compound synthesis. LED technology also facilitates the incorporation of light sources in a controlled setting where light spectra and intensity can be regulated. The objective of this study was to compare the effect of two commercial light spectra (S1: standard white light with 32.8% blue, 42.5% green, 21.7% red and 2.4% far red;S2: AP67 spectrum, designed for horticultural growth, with 16.9% blue, 20.5% green, 49.7% red and 12.3% far red) at two light intensities [LI: low intensity (78 µmol·m-2s-1 of photons for S1 and 62 µmol·m-2s-1 for S2, and HI: high intensity (102 and 100 µmol·m-2s-1 for S1 and S2, respectively)] on growth and antioxidant compound contents in two leafy vegetables: endive (Cichorium endivia L.) and lettuce (Lactuca ...
Agriculture, 2019
The aim of this study was to evaluate the growth characteristics and pigment content of tomato plantlets grown under various ratios of red (R) (661 nm) and blue (B) (449 nm) LED light. In this study, three different ratios of R and B (RB) light such as 5:01, 10:01, and 19:01 along with R (100%) were used. The photosynthetic photon flux density (PPFD), and photoperiod of the growth chamber was 120 ± 5 μmol m−2s−1 and 16/8 h (day/night), respectively. Tomato plantlets were cultured for six weeks in the growth chamber. It was shown that tomato plantlets had higher photosynthesis rate, higher pigments content, higher growth characteristics (e.g., number of leaves, leaf area, shoot number, root number, root length, dry, and fresh mass), and greater surviving rate under the R:B = 10:01 ratio among the treatments. The plantlets showed at least a threefold decrease in photosynthesis rate, as well as a significant abnormal stem elongation when grown under 100% R light. It is concluded that t...