• Title/Summary/Keyword: photosynthetic photon flux density

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Using Sunshine Duration to Estimate Photosynthetic Photon Flux Density at Taegu Korea (일조시간을 이용한 대구지방 광합성 광자선속밀도의 추정)

  • Suh, KyeHong
    • The Korean Journal of Ecology
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    • v.19 no.1
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    • pp.65-70
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    • 1996
  • The daily photosynthetic photon flux density incident on a horizontal surface was estimated with sunshine duration through daily global radiation at Taegu in Korea. The constant and coefficient of $\AA$ngstrom equation for global radiation were calculated as 0.1763 and 0.5012, respectively. The conversion factor from daily global radiation to daily photosynthetic photon flux density was determined as 2.2359.

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Illuminance Distribution and Photosynthetic Photon Flux Density Characteristics of LED Lighting with Periodic Lattice Arrangements

  • Jeon, Hee-Jae;Ju, Kang-Sig;Joo, Jai-Hwang;Kim, Hyun-Gyun
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.1
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    • pp.16-18
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    • 2012
  • LED lighting systems that combine lighting capability, emotional and physiological characteristics are required for lighting source and multifunctional applications. In this work, Simulation studies using optical analysis software packages, Light Tools, are presented. This is done to estimate the uniformity ratio of illuminance and photosynthetic photon flux density (PPFD) of the periodic 2D lattice arrangements, such as square, diamond, two-way bias quadrangular, hexagonal, and Kagome lattices, under the same transmissivity, absorptance and reflectivity. It has been found out that the two-dimensional Kagome lattice arrangement exhibited high uniformity ratio of illuminance and PPFD compared to other lattices. Accordingly, these results can be used to guide a design and improve the lighting environment which in turn would maximize the uniform distributions of illuminance.

Effects of Water Stress on Leaf Orientation, Apparent Photosynthetic Rate, Transpiration Rate, Yield and Its Related Traits in Soybean Plants (한발조건이 콩식물체의 엽운동, 광합성능, 증산량, 수량 및 관련 형질에 미치는 영향)

  • 천종은;김진호
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.37 no.4
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    • pp.313-319
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    • 1992
  • To investigate effects of water stress on apparent photosynthetic, transpiration rates, leaf orientation, yield and its related traits, four soybean varieties were planted on the Wagner pots in a plastic house covered with polyethylene film. As the light intensity and leaf temperature in a day increased, the movement of central leaflet in the second leaf of main stem occurred earlier than that of the lateral leaflet. The apparent photosynthetic rate of the central leaflet was higher than that of the lateral leaflet, but light intercept and leaf temperature of lateral leaflet were higher than those of the central leaflet. The apparent photosynthetic rate had highly positive correlation with the photon flux density, stomatal conductance and temperature, respectively. The photon flux density, stomatal conductance, transpiration and photosynthetic rates in the control were significantly higher than those in the water stress plot. The yield and its related traits in the water stress plot became decreased significantly in comparison with the control.

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Acclimation of maximum quantum yield of PSII and photosynthetic pigments of Panax quinquefolius L. to understory light

  • Fournier, Anick R.;T.A., John;Khanizadeh, Shahrokh;Gosselin, Andre;Dorais, Martine
    • Journal of Ginseng Research
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    • v.32 no.4
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    • pp.347-356
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    • 2008
  • Forest-grown American ginseng (Panax quinquefolius L.) is exposed to daily and seasonal light variations. Our goal was to determine the effect of understory light changes on the maximum quantum yield of photosystem II, expressed as $F_v/F_m$, and photosynthetic pigment composition of two-year-old plants. Understory light photon flux density and sunfleck durations were characterized using hemispherical canopy photography. Our results showed that understory light significantly affected the $F_v/F_m$ of American ginseng, especially during the initial development of the plants when light levels were the highest, averaging 28 mol $m^{-2}d^{-1}$. Associated with low $F_v/F_m$ during its initial development, American ginseng had the lowest levels of epoxidation state of the xanthophyll cycle of the season, suggesting an active dissipation of excess light energy absorbed by the chlorophyll pigments. As photon flux density decreased after the deployment of the forest canopy to less than 10 mol $m^{-2}d^{-1}$, chlorophyll a/b decreased suggesting a greater investment in light harvesting pigments to reaction centers in order to absorb the fleeting light energy.

Growth Model of Leaf Lettuce Based on the Cumulative Photosynthetic Photon Flux Density (적산일사량에 따른 상추 생육모델)

  • 문보흠;이병일
    • Proceedings of the Korean Society for Bio-Environment Control Conference
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    • 2002.04a
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    • pp.85-92
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    • 2002
  • 채소는 다른 작물에 비해 생육기간이 매우 짧기 때문에 환경의 영향을 많이 받는다. 특히 환경이 제어되는 시설에서 양액재배를 할 경우에는 생육이 왕성하므로 노지에 비해 재배기간을 단축시킬 수 있으며, 근권부 양액제어나 지상부 환경제어를 통해 고품질 채소를 생산할 수 있는 장점이 있다. 따라서 빠른 생육을 제어하거나 예측할 수 없어 수확적기를 놓치면 외관적 품질이 현저히 떨어지고 질적 품질도 저하하여 소비자의 기호에 맞추기 힘들게 된다. (중략)

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Effects of LED Light Quality of Urban Agricultural Plant Factories on the Growth of Daughter Plants of 'Seolhyang' Strawberry

  • Lee, Kook-Han
    • Journal of Environmental Science International
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    • v.27 no.10
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    • pp.821-829
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    • 2018
  • This study was conducted to examine the influence of Light-Emitting Diode (LED) light quality in urban agricultural plant factories on the growth and development of Seolhyang strawberry daughter plants in order to improve the efficiency of daughter plant growth and urban agriculture. LED light quality by demonstrated that above-ground growth and development were greatest for daughter plant 2. Daughter plant 1 showed the next highest growth and development, followed by daughter plant 3. Among the different qualities of LED light, the stem was thickest and growth rate of leaves was highest for R + B III (LED quality: red 660 nm + blue 450 nm/photosynthetic photon flux density (PPFD): $241-243{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and lowest for R (red $660nm/115-117{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). Plant height, leaf width, petiole length, and the leaf growth rate were highest for W (white fluorescent lamp/$241-243{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and lowest for R + B I (red 660nm+blue 450nm/$80-82{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). For above-ground growth and development, as the plants surpassed the seedling age, mixed light (red + blue), rather than monochromatic light (red or blue), and higher PPFD values tended to increase development. Regarding the quality of the LED light, daughter plant 2 showed the highest chlorophyll content, followed by daughter plant 1, and daughter plant 3 showed the least chlorophyll content. When the wavelength was monochromatic, chlorophyll content increased, compared to that when PPFD values were increased. Mixed light vitality was highest in daughter plant 2, followed by 1, and 3, showed increased photosynthesis when PPFD values were high with mixed light, in contrast to the results observed for chlorophyll content.

Effects of Light Intensity and Nutrient Level on Growth and Quality of Leaf Lettuce in a Plant Factory (식물공장내 광도와 배양액농도가 상추의 생육과 품질에 미치는 영향)

  • Park, Mi-Hee;Lee, Yong-Beom
    • Journal of Bio-Environment Control
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    • v.8 no.2
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    • pp.108-114
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    • 1999
  • This study was conducted to investigate the optimum environment for leaf lettuce (Lactuca sativa L. var. crispa) in a plant factory to increase mass-production efficiency of quality leaf lettuce. Transpiration rate and $CO_2$ assimilation rate were increased with increasing the photosynthetic photon flux density (PPFD). The highest fresh weight and dry weight were observed at the PPFD of 200 and 300 U moi $m^{-2}$ $s^{-l}$, respectively. The optimum aerial environment for the growth and quality of leaf lettuce in the plant factory was determined to be over 200 $\mu$mol $m^{-2}$ $s^{-1}$ for PPFB. Although the interaction between light intensity and nutrient level was not significant, the lettuce growth was the best under electrical conductivity (EC) of 1.8 mS $cm^{-1}$ / at high light intensity (250 $\mu$mol $m^{-2}$ $s^{-1}$ ) and EC of 2.4 mS cm-1 at low light level (150 $\mu$mol $m^{-2}$ $s^{-1}$ ) respectively.y.

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Meteorological Data Measured under Agrivoltaic Systems in Boseong-gun during Winter Barley Season (영농형 태양광 시설 하부의 미기상 관측 자료: 보성에서 2019년 11월부터 2020년 5월까지 가을보리 재배기간 동안)

  • Cho, Yuna;Yoon, Changyong;Kim, Hyunki;Moon, Hyundong;An, Kyu-Nam;Cho, Jaeil
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.22 no.3
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    • pp.144-151
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    • 2020
  • Agrivoltaic systems (AVS) is defined as combining farm-grown crops with photovoltaic panels (PV) installed several meters above the ground. Solar radiation (W/㎡), photosynthetic photon flux density (PPFD, µmol/㎡/s), air temperature (℃), vapor pressure (kPa), soil moisture (㎥/㎥), soil temperature (℃), wind direction (˚), and wind speed (m/s) were measured under the AVS in Boseong-gun during winter barley season. Data was collected by 5 minute interval. All data can download at Github site (https://github.com/chojaeil/AVS_Boseung). To gap-filling missing solar radiation data during about two weeks, the conversion coefficient from solar radiation to PPFD was estimated as 0.41. Further, according to the ratio of diffuse radiation to direct radiation, the maximum value among the twenty PPFD sensors under the AVS was related to the PPFD value of filed.

A Study on Growth of the Green Leaf Lettuce Depends on PPFD and Light Quality of LED Lighting Source for Growing Plant (식물재배용 LED 광원의 광질과 PPFD에 따른 청치마상추의 성장에 관한 연구)

  • Yang, Jun-Hyuk;Choi, Won-Ho;Park, Noh-Joon;Park, Dae-Hee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.2
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    • pp.142-147
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    • 2015
  • The artificial light sources for growth of plant are usually high-pressure sodium lamp, metal haloids lamp, and fluorescent light; however, these light sources have relatively weaker Red and Blue lights that are necessary for growth of plants. Especially the effect of Photosynthetic Photon Flux Density (PPFD) is pointed out as the weakness. Meanwhile, LED light source can be selected by specific wavelength to greatly improve the effect of PPFD. In this regard, this paper aims to investigate the promotion of plant growth by measuring photosynthetic photon flux density (hereafter referred to as PPFD) according to changes in light quality of the LED light sources. Towards this end, LED light sources for plant growth were produced with 4 kinds of mono-chromatic lights and 6 kinds of combined lights by mixing red, blue, green and white lights. A comparative analysis was conducted to investigate the effects of optical properties and PPFD on plants (green leaf lettuce) using the produced light sources. The results monochromatic light has fastest growth rate, but plant growth conditions have poor. This being so, mixed light is suitable for the green leaf lettuce.

Monitoring of plant induced electrical signal of broccoli (Brassica oleracea var. italica) under changing light and CO2 conditions (광 및 CO2 변화 조건에서 브로콜리(Brassica oleracea var. italica)의 전기적 신호 모니터링)

  • Park, Jin Hee;Kim, Han-Na
    • Journal of Applied Biological Chemistry
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    • v.64 no.4
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    • pp.351-356
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    • 2021
  • Changing environmental conditions can affect plant growth by influencing water and nutrient transport and photosynthesis. Plant physiological responses under changing environmental conditions can be non-destructively monitored using electrodes as plant induced electrical signal (PIES). Objective of the study was to monitor PIES in response to increased CO2 and decreased photosynthetic photon flux density (PPFD). The PIES increased during day time when transpiration and photosynthesis occurs and monitored CO2 concentration was negatively correlated to the PIES. Enhanced CO2 concentration slightly reduced PIES, but the effect of increased CO2 was limited by light intensity. The effect of reduced PPFD was not appeared immediately because water and nutrient transport was not promptly affected by the light. The study was conducted to evaluate short-term effect of increasing CO2 and decreasing PPFD, hence proline content and chlorophyll fluorescence was not significantly affected by the conditions.