Articles
Calculating and reporting key light ratios for plant research
Article number
1296_72
Pages
559 – 566
Language
English
Abstract
Recent advancements in light-emitting diode (LED) technology have provided excellent opportunities to precisely control the spectral output of lamps and to study the resulting impacts on plant growth and development.
Plant scientists often use light (or radiation) ratios to compare different light sources and assess their potential effects.
For example, based on the average plant response to photosynthetically active radiation, the red:blue ratio can be used to assess the effect a particular light source may have on plant growth and/or morphology.
In addition, many lighting companies market their products as having an optimal ‘light recipe’ that often includes a combination of specific wavelengths and specific light ratios, for example ‘4 to 1 red/blue’. However, the scientific literature does not provide exclusive definitions of the key wavebands that are used to calculate these ratios.
For example, red light is sometimes identified as light with a peak wavelength of 660 nm, and other times as all radiation across the 600-700 nm waveband.
As a result, calculated light ratios can have very different values, making comparisons among experiments challenging.
We used spectroradiometer data (280-800 nm) to determine key light ratios for sunlight and various electric lamps (INC, CFL, CMH, HPS, and LED). The calculated ratios included red:blue, red:green, green:blue, red:far-red and ultraviolet:blue.
Depending on the range of wavelengths used for each waveband, calculated values for the light ratios will be different.
This demonstrates the importance of standardized definitions for key wavebands and using such definitions will hopefully contribute to an easier interpretation of light ratios that are reported in the literature.
At a minimum, we hope to convey the importance of adequately presenting information about the specific waveband ranges used to calculate light (or radiation) ratios.
Plant scientists often use light (or radiation) ratios to compare different light sources and assess their potential effects.
For example, based on the average plant response to photosynthetically active radiation, the red:blue ratio can be used to assess the effect a particular light source may have on plant growth and/or morphology.
In addition, many lighting companies market their products as having an optimal ‘light recipe’ that often includes a combination of specific wavelengths and specific light ratios, for example ‘4 to 1 red/blue’. However, the scientific literature does not provide exclusive definitions of the key wavebands that are used to calculate these ratios.
For example, red light is sometimes identified as light with a peak wavelength of 660 nm, and other times as all radiation across the 600-700 nm waveband.
As a result, calculated light ratios can have very different values, making comparisons among experiments challenging.
We used spectroradiometer data (280-800 nm) to determine key light ratios for sunlight and various electric lamps (INC, CFL, CMH, HPS, and LED). The calculated ratios included red:blue, red:green, green:blue, red:far-red and ultraviolet:blue.
Depending on the range of wavelengths used for each waveband, calculated values for the light ratios will be different.
This demonstrates the importance of standardized definitions for key wavebands and using such definitions will hopefully contribute to an easier interpretation of light ratios that are reported in the literature.
At a minimum, we hope to convey the importance of adequately presenting information about the specific waveband ranges used to calculate light (or radiation) ratios.
Publication
Authors
T. Shelford, C. Wallace, A.J. Both
Keywords
blue, far-red, green, radiation, red, spectrum, supplemental lighting, ultraviolet
Groups involved
- Division Precision Horticulture and Engineering
- Division Greenhouse and Indoor Production Horticulture
- Working Group Organic Greenhouse Horticulture
- Working Group Protected Cultivation, Nettings and Screens for Mild Climates
- Working Group Light in Horticulture
- Working Group Vegetable Grafting
- Working Group Computational Fluid Dynamics in Agriculture
- Working Group Mechanization, Digitization, Sensing and Robotics
- Working Group Modelling Plant Growth, Environmental Control, Greenhouse Environment
- Working Group Greenhouse Environment and Climate Control
- Working Group Design and Automation in Integrated Indoor Production Systems
- Commission Agroecology and Organic Farming Systems
- Division Landscape and Urban Horticulture
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