1、ANSI/ASABE S640 JUL2017 Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms) American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement of engineering applicab
2、le to agricultural, food, and biological systems. ASABE Standards are consensus documents developed and adopted by the American Society of Agricultural and Biological Engineers to meet standardization needs within the scope of the Society; principally agricultural field equipment, farmstead equipmen
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10、/ASABE S640 JUL2017 Copyright American Society of Agricultural and Biological Engineers 1 ANSI/ASABE S640 JUL2017 Approved July 2017 as an American National Standard Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms) Developed by the ES-311, Electromagnetic Radia
11、tion Application for Plants Committee; approved as an ASABE standard July 2017; approved by ANSI July 2017. Keywords: Metrics, Radiation, Plant Growth, Horticulture. 0 Introduction The conventional radiation metric for plant growth applications is photosynthetically active radiation (PAR), as introd
12、uced by McCree 1. It is based on field and growth chamber measurements of photosynthesis in 22 common plant species, and represents the CO2 assimilation per mole of incident photons at specific wavelengths between 400 nm and 700 nm. PAR is expressed in terms of the photosynthetic photon flux (PPF) a
13、nd photosynthetic photon flux density, (PPFD). These metrics can be measured with a suitably calibrated quantum sensor or derived from spectroradiometer measurements. PPF is the amount of radiation emitted from a source. PPFD indicates the amount of radiation that is incident upon a unit of surface
14、area. Plant growth, architecture, and flowering, however, involve more than just photosynthesis. Plants have numerous photoreceptors that absorb and are activated or deactivated by specific spectral regions from UVB to far-red. Ultraviolet radiation, for example, may induce changes in leaf and plant
15、 morphology 2. As another example, the far-red isoform of phytochrome, which is responsible for many plant functions including seed germination, flower induction, plant height, and leaf expansion, has a spectral absorptance peak at 730 nm 3. These phenomena have previously been of interest mostly to
16、 plant biologists, as the electromagnetic radiation sources available for plant growth applications were limited to incandescent, fluorescent, and high-intensity discharge (e.g. high-pressure sodium and metal halide) lamps. The light sources customarily used by horticulturalists were often designed
17、for human perception or general illumination purposes, rather than optimized for plant applications. Thus, simplifying incident light intensity to PPFD measurements provided adequate precision with a useful degree of standardization. This has all changed with the introduction of solid-state lighting
18、 for horticultural applications. Horticulturists quickly realized that light-emitting diodes (LEDs) appeared adequate for the photosynthetic needs of many plants, as their spectral output can coincide with the spectral absorptance of leaves and the action spectrum of photosynthesis. Furthermore, the
19、 range from ultraviolet to far-red LEDs has become available for horticultural radiation applications. Commercial growers and horticultural researchers alike now have the ability to “tune” the spectral output to complement the action spectra of any plant pigment or species or pursue specific photomo
20、rphological responses. This ability is important not only for the inclusion of ultraviolet and far-red radiation in horticultural lighting, but also because the spectral power distribution (SPD) of plant growth radiation is important. Green radiation in particular, while not highly absorbed by isola
21、ted chlorophyll A and B, nevertheless has significant impact on both photosynthesis and photomorphogenesis of the leaf and whole plant (for example, Reference 4 and Reference 5). Unlike traditional electric lighting for horticulture, the use of LED technology allows for the inclusion of many differe
22、nt wavelengths of radiation as well as their proportions to each other. Solid-state lighting has further emphasized the need for horticultural radiation metrics beyond that of PAR and PPFD. The availability of solid-state lighting has contributed to a significant increase in the understanding of pla
23、nt photobiological responses, and it offers the potential to specifically trigger these with more control. This document ANSI/ASABE S640 JUL2017 Copyright American Society of Agricultural and Biological Engineers 2 presents equivalent metrics and associated definitions for ultraviolet and far-red ra
24、diation, as well as spectral power distribution. In addition to establishing the appropriate definition of metrics for plant growth, this document also presents equivalent metrics for defining UV and FR radiation often associated with photomorphological effects in plants. 1 Scope This document provi
25、des definitions and descriptions of metrics used for radiation measurements for plant (photosynthetic organisms) growth and development. This document does not cover display aspects and human visualization. 2 Normative References The following referenced documents are indispensable for the applicati
26、on of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ASAE EP402, Radiation Quantities and Units. ANSI/ASAE EP411, Guidelines for Measuring and Reporting Environmental Param
27、eters for Plant Experiments in Growth Chambers. ANSI/IES RP-16-10, Nomenclature and Definitions for Illuminating Engineering, New York, NY: Illuminating Engineering Society. IES TM-27-14, IES Standard Format for the Electronic Transfer of Spectral Data, New York, NY: Illuminating Engineering Society
28、. CIE Lighting Vocabulary, http:/eilv.cie.co.at/termlist. ISO Standard 21348:2007, Space environment (natural and artificial) Process for determining solar irradiances. Geneva, Switzerland: International Organization for Standardization. 3 Definitions 3.1 Daily Light Integral (DLI): Photosynthetic p
29、hoton flux density integrated over a 24-hour period typically coinciding with the 24 hours of a calendar day). 3.2 Far-red radiation: For horticultural applications, far-red radiation is defined as electromagnetic radiation with wavelengths between 700 nm and 800 nm. 3.3 Irradiance: Irradiance is ra
30、diant flux per unit area incident upon a point on a surface. 3.4 Photobiology: Photobiology is broadly defined as the study of all biological phenomena involving electromagnetic radiation. It is recognized that photobiological responses are the result of chemical and/or physical changes induced in b
31、iological systems by non-ionizing radiation. 3.5 Photochemistry: Photochemistry is the underlying mechanism for all photobiology. 3.6 Photomorphogenesis: Photomorphogenesis is defined as any change in the morphology (shape) or composition (e.g., flowering induction, secondary metabolite production)
32、of a plant or plant part that occurs in response to exposure to electromagnetic radiation. 3.7 Photon: A photon is a quantum (smallest quantity) of electromagnetic radiation. ANSI/ASABE S640 JUL2017 Copyright American Society of Agricultural and Biological Engineers 3 3.8 Photon flux: Photon flux, a
33、lso commonly referred to as quantum flux, is the rate of flow of photons. 3.9 Photon Flux Density (PFD): Photon flux density is the rate of flow of photons per unit area incident upon a point on a surface. 3.10 Photoperiod: The photoperiod is the cumulative amount of time during a specific period of
34、 time (typically 24 hours) in which the plant is exposed to electromagnetic radiation that significantly impacts plant photosynthesis and/or photomorphogenesis. It is typically reported in hours and fractions thereof. 3.11 Photosynthesis: Photosynthesis is a process wherein energy from radiation is
35、converted into chemical energy. The electrons obtained through the oxidation of water are used to reduce carbon dioxide to organic matter, mainly carbohydrates. Oxygen is formed during this process. 3.12 Photosynthetic Photon Flux (PPF): Photosynthetic photon flux is the rate of flow of photons with
36、in the PAR waveband from a radiation source. 3.13 Photosynthetic Photon Flux Density (PPFD): Photosynthetic photon flux density is the rate of PAR photons per unit area incident upon a point on a surface. 3.14 Photosynthetically Active Radiation (PAR): Photosynthetically active radiation designates
37、the spectral range (waveband) of radiation, from 400 to 700 nm, which by definition photosynthetic organisms are able to use in the process of photosynthesis. The measured result of PAR can be reported as PPF or PPFD. 3.15 Radiant energy: Radiant energy is energy in the form of electromagnetic radia
38、tion. 3.16 Radiant flux: Radiant flux is the rate of flow of radiant energy. 3.17 Radiant intensity: In a given direction from a source, radiant intensity is the radiant flux per unit solid angle leaving the source. 3.18 Spectral irradiance: Spectral irradiance is irradiance per unit wavelength at a
39、 specified wavelength. 3.19 Spectral Power Distribution (SPD): Spectral power distribution (SPD) is an enumeration or graphical display of spectroradiometric values (such as spectral irradiance or spectral radiant flux) over a specific range of wavelengths. 3.20 Spectral radiant flux: Spectral radia
40、nt flux is radiant flux per unit wavelength interval at a specified wavelength. 3.21 Spectral radiant intensity: In a given direction from a source, spectral radiant intensity is the spectral radiant flux per unit solid angle leaving the source. 3.22 Spectral Quantum Distribution (SQD): A spectral q
41、uantum distribution (SQD, based on photon flux) is an enumeration or graphical display of spectroradiometric values over a specific range of wavelengths. 3.23 Spectral Photon (Quantum) Flux: Spectral photon flux is photon flux per unit wavelength at a specified wavelength. 3.24 Spectral photon (quan
42、tum) flux density: Spectral photon flux density is photon flux density per unit wavelength at a specified wavelength. 3.25 Ultraviolet Radiation: Ultraviolet radiation is defined as electromagnetic radiation with wavelengths between 100 nm and 400 nm. The range between 100 nm and 400 nm is commonly
43、subdivided into: UV-A: 315 nm to 400 nm; UV-B: 280 nm to 315 nm; UV-C: 100 nm to 280 nm. ANSI/ASABE S640 JUL2017 Copyright American Society of Agricultural and Biological Engineers 4 4 Quantities and Units Based on Radiation Measurements The summary of quantities and units based on radiation measure
44、ments is shown in Table 1. 4.1 Radiation 4.1.1 Radiant Flux The radiant flux ( ) is measured or calculated in the wavelength interval from 1 to 2, and is defined as: =21 d)( where () is the spectral radiant flux, measured in watts per nm. The unit of is watts (Wr). 4.1.2 Radiant Intensity For a give
45、n direction from a radiation source, radiant intensity is measured as: ddI = where d is the radiant flux leaving the radiation source in an elementary cone containing a given direction with solid angle d. The unit of I is watts per steradian (Wr sr-1). 4.1.3 Radiant Efficiency The radiant efficiency
46、 () is the radiant flux (measured in watts) divided by the input electric power. It is unitless. 4.2 Photosynthetically Active Radiation (PAR) 4.2.1 Photosynthetic Radiant Flux The radiant flux (e) is measured or calculated without weighting factors across the wavelength interval of 400 nm to 700 nm
47、, and is defined as: =700400de)( where () is the spectral radiant flux, measured in watts per nm. The unit of e is expressed in watts (Wr). 4.2.2 Photosynthetic Radiant Intensity For a given direction from a radiation source, photosynthetic radiant intensity is defined as: ddIee= where de is the pho
48、tosynthetic radiant flux leaving the radiation source in an elementary cone containing the given direction with the solid angle d. The unit of Ie is expressed in watts per steradian (Wr sr-1). 4.2.3 Photosynthetic Radiant Efficiency The photosynthetic radiant efficiency (e) is the photosynthetic rad
49、iant flux (measured in watts) divided by the input electric power. It is unitless. ANSI/ASABE S640 JUL2017 Copyright American Society of Agricultural and Biological Engineers 5 4.3 Ultraviolet Radiation For horticultural applications, UV radiation is limited to UV-A and UV-B radiation. In this document, ultraviolet radiation refers only to UV-A and UV-B. Solar UV-C radiation is not considered because it is almost completely absorbed by the Earths atmosphere. 4.3.1 Ultraviolet Radiant F
