Closed-type Plant Production System Research Articles

Growth and Phytochemical Contents of Spinach as Affected by Different Type of Fluorescent Lamp in a Closed-type Plant Production System

Growth and Phytochemical Contents of Spinach as Affected by Different Type of Fluorescent Lamp in a Closed-type Plant Production System

Development of a Planting Density-Growth-Harvest Chart for Common Ice Plant Hydroponically Grown in Closed-type Plant Production System

Development of a Planting Density-Growth-Harvest Chart for Common Ice Plant Hydroponically Grown in Closed-type Plant Production System

Development of planting-density growth harvest (PGH) charts for quinoa (Chenopodium quinoa Willd.) and sowthistle (Ixeris dentata Nakai) grown hydroponically in closed-type plant production systems

When designing a plant production system, it is crucial to perform advanced estimation of growth and productivity in relation to cultivation factors. In this study, we developed Planting-density Growth Harvest (PGH) charts to facilitate the estimation of crop growth and harvest factors such as growth rate, relative growth rate, shoot fresh weight, harvesting time, marketable rate, and marketable yield for quinoa (Chenopodium quinoa Willd.) and sowthistle (Ixeris dentata Nakai). The plants were grown in a nutrient film technique (NFT) system in a closed-type plant factory under fluorescent lamps with three-band radiation under a light intensity of 140 μmol·m-2 ·s-1, with a 12-h/12-h (day/night) photoperiod. We analyzed the growth and yield of quinoa and sowthistle grown in nutrient solution at EC 2.0 dS·m-1 under four planting densities: 15 cm between rows with a within-row distance of 15 × 10 cm (67 plants/m 2), 15 × 15 cm (44 plants/m2), 15 × 20 cm (33 plants/m2), and 15 × 25 cm (27 plants/m2). Crop growth rate, relative growth rate, and lost time were closely correlated with planting density. We constructed PGH charts based on the growth data and existing models. Using these charts, growth factors could easily be determined, including growth rate, relative growth rate, and lost time, as well as harvest factors such as shoot fresh weight, marketable yield per area, and harvesting time, based on at least two parameters, for instance, planting density and shoot fresh weight.

The research on LED supplementary lighting system for plants

As an artificial light source, light-emitting diodes (LEDs) can be used to make the vegetables grow more quickly in closed-type plant production systems, especially in the environment of the light intensity is insufficient. In order to study the improvement of the cherry tomato growth rate using the LED light source, we have a design with a certain ratio of red and blue (relative spectral distribution) LED lighting system and carry out the manufacture of the LED supplementary lighting system. We carried on a track on the growth situation for a group of cherry tomatoes under the LED system and the other group of cherry tomatoes without the LED supplementary lighting system. We observed and compared with the growth of the two group of tomatoes in different growing period. In our experiment, we use supplementary lighting system with the red and blue LEDs which peak wavelenth are respectively 650nm and 460nm, and the relative spectral distribution ratio is 4:1. The experimental results showed that the LED supplementary lighting system significantly improved the growth speed of tomatoes. Because of the difference preference for the wavelength between the stem and leaf growth stage and the blooming and bearing fruit growth stage, this paper presents the red and blue light proportion choice switch which can be applied to the LED supplementary lighting system.

Increase in biomass and bioactive compounds in lettuce under various ratios of red to far-red LED light supplemented with blue LED light

The aim of this study was to analyze the growth and bioactive compounds of lettuce in response to far-red LED light supplemented with a combination of red and blue LED light. Sixteen-day-old red leaf lettuce seedlings were transplanted to a growth chamber equipped with red, blue, and far-red LEDs. After setting the ratio of blue (B) to red (R) LEDs to 2:8, the ratio of R to far-red (FR) LEDs was adjusted to 0.7, 1.2, 4.1, or 8.6 (B+R/FR 0.7, 1.2, 4.1, or 8.6). Additionally, plants were irradiated with combined B and R LEDs (B+R) and fluorescent lamps (control) for 24 days. Growth characteristics including cell division rate, epidermal cell density and thickness, and antioxidant phenolic compounds were measured. Supplementation with FR LED light improved shoot and root growth compared to plants under B+R and control treatment. B+R/FR 1.2 treatment resulted in the highest shoot fresh weight and leaf area on day 24 of treatment. Obvious activation of the G2M phase was not observed in plants under far-red treatment, and most far-red treatments besides B+R/FR 4.1 increased the epidermal cell size. Plants treated with B+R/FR ratios of only 0.7 and 1.2 had significantly higher total phenolic levels, antioxidant activity, chlorogenic acid contents, and caffeic acid contents per plant than the control. These results suggest that supplementing the existing visual light spectrum, such as red and blue light, with far-red LEDs improves lettuce growth and bioactive compound content in a closed-type plant production system.

Growth, photosynthetic and antioxidant parameters of two lettuce cultivars as affected by red, green, and blue light-emitting diodes

The addition of green light-emitting diodes (LEDs) to a combination of red and blue LEDs, which promote photosynthesis and growth in plants, is known to enhance plant growth in closed-type plant production systems. However, there is limited information on the effects of supplementary green light. This study aimed to determine the effect of red (R), green (G), and blue (B) LED ratios on the growth, photosynthetic, and antioxidant parameters in two lettuce (Lactuca sativa) cultivars, red leaf ‘Sunmang’ and green leaf ‘Grand Rapid TBR’. The seedlings were grown for 18 days and then cultivated in growth chambers equipped with LED lighting systems for 4 weeks. Combinations of six LED lighting sources (R:B = 9:1, 8:2, 7:3; R:G:B = 9:1:0, 8:1:1, 7:1:2) were manufactured to emit red (655 nm), blue (456 nm), or green (518 nm) lights under photosynthetic photon flux density of 173 ± 3 μmol·m-2·s-1. Red LEDs were found to improve growth characteristics such as fresh and dry weights of shoots and roots, and leaf area in combination with blue LEDs. The substitution of blue with green LEDs in the presence of a fixed proportion of red LEDs enhanced the growth of lettuce. In particular, the fresh weights of red leaf lettuce shoots under R8G1B1 were about 61% higher than those under R8B2. Furthermore, analysis of leaf morphology, transmittance, cell division rate, and leaf anatomy under treatments with green LEDs supported the enhanced growth of the two lettuce cultivars tested. Meanwhile, growth under blue LEDs led to the accumulation of antioxidant parameters in ‘Sunmang’. Thus, the results of this study suggest that the percentage of red, green, and blue LEDs is an important factor for the growth, development, and biosynthesis of secondary metabolites in plants and especially the supplemental irradiation of green LEDs based on the combination of red and blue LEDs can improve lettuce growth.

Growth and antioxidant phenolic compounds in cherry tomato seedlings grown under monochromatic light-emitting diodes

Light-emitting diodes (LEDs) can be used in closed-type plant production systems as an artificial light source. Here, we determined the effects of monochromatic LEDs on the growth and production of phenolic antioxidants in cherry tomato seedlings (Solanum lycopersicum L. ‘Cuty’). Two week-old seedlings germinated under normal growing conditions were transplanted into a growth chamber equipped with various monochromatic LEDs and fluorescent lamps (control), and cultivated for 4 weeks. Fresh weights of shoots and roots under LED treatment, especially, red or green, were higher than those under the control light at 4 weeks. The SPAD value of seedlings grown under blue LEDs was significantly lower than in seedlings grown under other LEDs. The plant height, stem length, and internode length of tomato seedlings grown under blue LEDs were the highest. Blue LEDs induced 1.5–2.2-fold higher stem length than red and white LEDs. Expansin gene expression was the highest under blue LEDs, consistent with the effect on stem length. Blue LEDs stimulated the biosynthesis of total phenolics, antioxidants, and total flavonoids in tomato seedlings. Specifically, the antioxidant capacity of seedlings grown under blue LEDs was 2.1-folds higher than that in seedlings grown under green LEDs. Thus, manipulating light quality using LEDs is a crucial factor for growth and antioxidant production in cherry tomato seedlings.

Growth Model of Common Ice Plant (Mesembryanthemum crystallinum L.) Using Expolinear Functions in a Closed-type Plant Production System

본 연구는 완전제어형 식물공장에서 선형 지수 함수를 이용하여 common ice plant의 생육과 수량 모델을 개발하고자 수행되었다. 식물공장 유형은 완전제어형 식물공장형태로 인공광원은 삼파장 형광등을 사용하였으며, 광주기는 12시간 일장주기였다. 광도는 <TEX>$200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$</TEX>로 조절하였다. 수경재배시스템은 3단으로 구성된 박막수경(NFT)시스템이었다. 식물공장내 온도, 상대습도와 이산화탄소 농도는 ON/OFF 제어하였다. 선형 지수 함수를 사용한 common ice plant의 정식 후 일수, 적산온도 및 적산일사량에 따른 엽면적, 단위 면적당 지상부 생체중과 건물중 및 광사용효율은 선형 지수적인 형태들을 보였다. 개체당 지상부 생체중과 개체당 지상부 건물중간의 관계는 직선적인 관계를 보였으며, 정식 후 30일째 common ice plant의 광사용효율(light use efficiency)은 <TEX>$3.3g{\cdot}MJ^{-1}$</TEX>이었다. 결론적으로, 선형 지수 함수는 완전제어형 식물공장에서 common ice plant의 생육과 수량을 정량적으로 예측하는데 유용한 함수로 사용될 수 있었다. The objective of this study was to make growth and yield models for common ice plant (Mesembryanthemum crystallinum L.) using expolinear functional equations in a closed-type plant production system. Three-band radiation type fluorescent lamps with a 12-hours photoperiod were used, and the light intensity was <TEX>$200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$</TEX>. Nutrient film systems with three layers were used for plant growth. Environmental conditions, such as air temperature, relative humidity and <TEX>$CO_2$</TEX> concentration were controlled by an ON/OFF operation. Leaf area, shoot fresh and dry weights, light use efficiency of common ice plant as function of days after transplanting, accumulative temperature and accumulative radiation were analyzed. Leaf area, shoot fresh and dry weights per area were described using an expolinear equation. A linear relationship between shoot dry and fresh weights was observed. Light use efficiency of common ice plant was <TEX>$3.3g{\cdot}MJ^{-1}$</TEX> at 30 days after transplanting. It is concluded that the expolinear growth model can be a useful tool for quantifying the growth and yield of common ice plant in a closed plant production system.

Growth Model of Sowthistle (Ixeris dentata Nakai) Using Expolinear Function in a Closed-type Plant Production System

The objective of this study was to make growth and yield models of sowthistle (Ixeris dentata Nakai) by using an expolinear functional equation in a closed-type plant production system. The growth and yield of hydroponically-grown sowthistle were investigated under four different planting distances (15 × 10, 15 × 15, 15 × 20, and 15 × 25 cm). Shoot dry weights per plant was the highest at 15 × 25 cm, but was the lowest at 15 × 10 cm. Shoot dry weights per area was the highest at 15 × 15 cm, but was the lowest at 15 × 25 cm. The optimum planting density and planting distance for yield of sowthistle were 44 plants/m 2 and 15 × 15 cm, respectively. Shoot dry weights per plant and per area were showed as an expolinear type functional equation. A linear relationship between shoot dry and fresh weights was observed to be linear regardless of the planting distance. Crop growth rate, relative growth rate and lost time in an expolinear functional equation showed quadratic function form. Radiation use efficiency of sowthistle was 4.3-6.1 g·MJ -1 . The measured and estimated shoot dry weights showed a good agreement using days after transplanting as input data. It is concluded that the expolinear growth model can be a useful tool for quantifying the growth and yield of sowthistle in a closed-type plant production system.

Growth and phenolic content of sowthistle grown in a closed-type plant production system with a UV-A or UV-B lamp

This study was conducted to determine the effects of UV-A and UV-B wavelengths on the growth and content of antioxidant phenolic compounds in sowthistle (Ixeris dentata Nakai), a medicinal plant, grown in a closed plant-production system. In study I, sowthistle plants were continuously exposed to UV-A light. In study II, two UV treatments [repeated UV-B (R): 4 h·d−1 for 6 days, gradual UV-B (G): from 1 to 7 h·d−1 for 6 days] were applied to the sowthistle plants. As a result, contents of total phenolics and antioxidants in UV-A-treated plants were significantly (50 and 30%, respectively) higher than those in the control plants after 3 d of UV treatment without growth inhibition. Moreover, plants continuously exposed to UV-A for 5 d had 50% higher total flavonoid content than the control. The phenylalanine ammonia-lyase (PAL) activity supported the accumulation of phytochemicals in plants exposed to UV-A. The UV-B (R) treatment led to a more rapid decrease in the chlorophyll fluorescence ratio than UV-B (G) treatment. The UV-B (R) or UV-B (G) treatment produced more total phenolics, flavonoids, and antioxidants, although both UV-B treatments significantly inhibited plant growth measured at 2 days after treatment. The UV irradiation also enhanced PAL activity at 2 and 3 days after treatment, suggesting biosynthetic activation of secondary metabolites. Therefore, application of UV-A or UV-B light can be used as a strategy to improve antioxidant phenolic compounds of sowthistle plants grown in closed plant production systems.

Growth of Lettuce in Closed-Type Plant Production System as Affected by Light Intensity and Photoperiod under Influence of White LED Light

Growth of Lettuce in Closed-Type Plant Production System as Affected by Light Intensity and Photoperiod under Influence of White LED Light

Leaf Shape, Growth, and Antioxidant Phenolic Compounds of Two Lettuce Cultivars Grown under Various Combinations of Blue and Red Light-emitting Diodes

Light-emitting diodes (LEDs) of short wavelength ranges are being developed as light sources in closed-type plant production systems. Among the various wavelengths, red and blue lights are known to be effective for enhancing plant photosynthesis. In this study, we determined the effects of blue and red LED ratios on leaf shape, plant growth, and the accumulation of antioxidant phenolic compounds of a red leaf lettuce (Lactuca sativa L. ‘Sunmang’) and a green leaf lettuce (Lactuca sativa L. ‘Grand Rapid TBR’). Lettuce seedlings grown under normal growth conditions (20 °C, fluorescent lamp + high-pressure sodium lamp 177 ± 5 μmol·m−2·s−1, 12-hour photoperiod) for 18 days were transferred into growth chambers that were set at 20 °C and equipped with various combinations of blue (456 nm) and red (655 nm) LEDs [blue:red = 0:100 (0 B), 13:87 (13 B), 26:74 (26 B), 35:65 (35 B), 47:53 (47 B) or 59:41 (59 B)] under the same light intensity and photoperiod (171 ± 7 μmol·m−2·s−1, 12-hour photoperiod). Leaf width, leaf length, leaf area, fresh and dry weights of shoots and roots, chlorophyll content (SPAD value), total phenolic concentration, total flavonoid concentration, and antioxidant capacity were measured at 2 and 4 weeks after the onset of LED treatment. The leaf shape indices (leaf length/leaf width) of the two lettuce cultivars subjected to blue LEDs treatment were similar to the control, regardless of the blue-to-red ratio during the entire growth stage. However, 0 B (100% red LED) induced a significantly higher leaf shape index, which represents elongated leaf shape, compared with the other treatments. Increasing blue LED levels negatively affected lettuce growth. Most growth characteristics (such as the fresh and dry weights of shoots and leaf area) were highest under 0 B for both cultivars compared with all other LED treatments. For red and green leaf lettuce cultivar plants, shoot fresh weight under 0 B was 4.3 and 4.1 times higher compared with that under 59 B after 4 weeks of LED treatment, respectively. In contrast, the accumulation of chlorophyll, phenolics (including flavonoids), and antioxidants in both red and green leaf lettuce showed an opposite trend compared with that observed for growth. The SPAD value (chlorophyll content), total phenolic concentration, total flavonoid concentration, and antioxidant capacity of lettuces grown under high ratios of blue LED (such as 59 B, 47 B, and 35 B) were significantly higher compared with 0 B or control conditions. Thus, this study indicates that the ratio of blue to red LEDs is important for the morphology, growth, and phenolic compounds with antioxidant properties in the two lettuce cultivars tested.

Growth and phenolic compounds of Lactuca sativa L. grown in a closed-type plant production system with UV-A, -B, or -C lamp.

The production of high-quality crops based on phytochemicals is a strategy for accelerating the practical use of plant factories. Previous studies have demonstrated that ultraviolet (UV) light is effective in improving phytochemical production. This study aimed to determine the effect of various UV wavelengths on growth and phenolic compound accumulation in lettuce (Lactuca sativa L.) grown in a closed-type plant production system. Seven days, 1 day and 0.25 day were determined as the upper limit of the irradiation periods for UV-A, -B, and -C, respectively, in the lettuce based on physiological disorders and the fluorescence parameter F(v)/F(m). Continuous UV-A treatment significantly induced the accumulation of phenolic compounds and antioxidants until 4 days of treatment without growth inhibition, consistent with an increase in phenylalanine ammonia lyase (PAL) gene expression and PAL activity. Repeated or gradual UV-B exposure yielded approximately 1.4-3.6 times more total phenolics and antioxidants, respectively, than the controls did 2 days after the treatments, although both treatments inhibited lettuce growth. Repeated UV-C exposure increased phenolics but severely inhibited the growth of lettuce plants. Our data suggest that UV irradiation can improve the accumulation of phenolic compounds with antioxidant properties in lettuce cultivated in plant factories.

단색 발광다이오드에서 자란 축면상추 두 품종의 엽형, 생장 및 기능성 물질

Abstract. As an artificial light source, light-emitting diode (LED) with a short wavelength range can be used in closed-type plant production systems. Among various wavelength ranges in visible light, individual light spectra induce distinguishing influences on plant growth and development. In this study, we determined the effects of monochromatic LEDs on leaf shape index, growth and the accumulation of phytochemicals in a red leaf lettuce ( Lactuca sativa L. ‘Sunmang’) and a green leaf lettuce ( Lactuca sativa L. ‘Grand rapid TBR’). Lettuce seedlings grown under normal grow ing conditions (20 ℃, fluorescent lamp + high pressure sodium lamp, 130 ± 5 µmol ･m -2 ･s -1 , 12 hours photoperiod) for 18 days were transferred into incubators at 20 ℃ equipped with various monochromatic LEDs (blue LED, 456 nm; green LED, 518 nm; red LED, 654 nm; white LED, 456 nm + 558 nm) under the same light intensity and photoperiod (130 ± 7 µmol ･m -2 ･s -1 , 12 hours photoperiod). Leaf leng th, leaf width, leaf area, fresh and dry weights of shoots and roots, shoot/root ratio, SPAD value, total phenolic concentration, antioxidant capacity, and the expression of a key gene involved in the biosynthesis of phenolic compounds, phenylalanine ammonia-lyase (PAL), were measured at 9 and 23 days after transplanting. The leaf shape indexes of both lettuce cultivars subjected to blue or white LEDs were similar with those of control during whole growth stage. However, red and green LEDs induced significantly higher leaf shape index than the other treatments. The green LED had a negative impact on the lettuce growth. Most of growth characteristics such as fresh and dry weights of shoots and leaf area were the highest in both cultivars subjected to red LED treatment. In case of red leaf lettuce plants, shoot fresh weight under red LED was 3.8 times higher than that under green LED at 23 days after transplanting. In contrast, the accumulation of chlorophyll, phenolics including antioxidants in lettuce plants showed an opposite trend compared with growth. SPAD value, total phenolic concentration, and antioxidant capacity of lettuce grown under blue LED were significantly higher than those under other LED treatments. In addition, PA L gene was remarkably activated by blue LED at 9 days after transplanting. Thus , this study suggested that the light quality using LEDs is a crucial factor for morphology, growth, and phytochemicals of two lettuce cultivars.

밀폐형 식물생산시스템에서 인공광원과 광조사 시간에 따른 상추의 생장 및 안토시아닌 함량

This study was conducted to examine the effect of artificial light source and photoperiod on the growth of leaf lettuce (Lactuca sativa L.) 'Seonhong Jeokchukmyeon' in a closed-type plant production system. Seedlings were grown under 3 light sources, fluorescent lamp (FL, Philips Co. Ltd., the Netherlands), WL #1 (Hepas Co. Ltd., Korea), and WL #2 (FC Poibe Co., Ltd., Korea), each with 3 photoperiods, 12/12, 18/6, and 24/0 (Light/Dark). An irradiance spectrum analysis showed that FL has various peaks in the 400-700 nm range, while WL #1 and WL #2 have only one monochromatic peak at 450 and 550 nm, respectively. The greatest plant height, fresh and dry weights were obtained in the 24/0 (Light/Dark) photoperiod. The 24/0 (Light/Dark) photoperiod treatment promoted vegetative growth of the leaf area. Length of the longest root, number of leaves, fresh weight, and total anthocyanin contents were greater in FL than in either WL #1 or #2. The greatest chlorophyll fluorescence (Fv/Fm) was found in the 12/12 (Light/Dark) photoperiod with FL treatment. The energy use efficiency of the LED increased by about 35-46% as compared to FL. Results suggest a possibility of LED being used as a substitute light source for fluorescent lamp for lettuce cultivation in a plant factory system.

식물생장용 LED 램프의 적정 수냉조건 및 열교환량 분석

This study was conducted to compare the characteristics of heat dissipated from LED lamps with water cooling method and natural cooling method in a closed-type plant production system (CPPS) and to determine the optimum water temperature and flow rate for LED lamps with water cooling method. The experiments were performed in CPPS maintained at temperature of <TEX>$24^{\circ}C$</TEX> and humidity of 70%. As compared to the LED lamps operated at water temperature of <TEX>$22.5{\pm}1.2^{\circ}C$</TEX> and flow rate of <TEX>$1,521{\pm}3.3\;mL{\cdot}min^{-1}$</TEX>, air temperature under LED lamps with natural cooling was approximately increased by <TEX>$1^{\circ}C$</TEX> and photosynthetic photon flux was decreased by <TEX>$10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$</TEX>. PPF illuminated from LED lamps was affected by forward voltage varied by the surface temperature of LED lamps. Forward voltage of LED lamps was decreased with increasing surface temperature and then PPF was proportionately decreased. Five levels (<TEX>$14^{\circ}C,\;17^{\circ}C,\;20^{\circ}C,\;23^{\circ}C,\;26^{\circ}C$</TEX>) of water temperature and three levels (<TEX>$500\;mL{\cdot}min^{-1}$</TEX>, <TEX>$1,000\;mL{\cdot}min^{-1}$</TEX>, <TEX>$1,500\;mL{\cdot}min^{-1}$</TEX>) of flow rate were provided to analyze the change of surface temperature and heat exchange of LED lamps. Heat exchange was increased with decreasing water temperature and increasing flow rate. At flow rate of <TEX>$1,000-1,500\;mL{\cdot}min^{-1}$</TEX> and water temperature of 22.0-<TEX>$22.6^{\circ}C$</TEX>, surface temperature of LED lamps can be approached to <TEX>$24^{\circ}C$</TEX> that was almost same as air temperature in CPPS. The calorific value generated from LED lamps used in the study was estimated to be <TEX>$103.0\;kJ{\cdot}h^{-1}$</TEX>.

人工光型植物工場(&lt;小特集&gt;農業生産技術の将来展望)

人工光型植物工場(&lt;小特集&gt;農業生産技術の将来展望)