6/10/2014
Light emitting diode (LED)
Lighting for Greenhouse Crops
A.J. Both
Associate Extension Specialist
Dept. of Environmental Sciences
both@aesop.rutgers.edu
•Electromagnetic radiation spectrum
http://www.zulyzami.com
http://upload.wikimedia.org
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• Why do plants need light?
 Photosynthesis (growth and development)
Other processes:
 Photoperiodism (daylength)
 Photomorphogenesis (light affects shape)
 Phototropism (sunflower)
 Photodormancy (seeds)
Note: Without the ability of plants to convert light into biomass, many living organisms would not survive on our planet, including us!
Relative Quantum Efficiency and Eye Sensitivity 1
R = 620‐740
O = 590‐620
Y = 565‐590
G = 500‐565
B = 435‐500
I 420 435*
I = 420‐435*
V = 380‐420
0.8
0.76
0.69
0.6
0.4
02
0.2
Photosynthetically
Active Radiation (PAR)
0
300
350
400
450
500
550
600
650
700
750
800
nm
430
475
500
555 565
610
*Disputed (CRC Handbook of Fundamental Spectroscopic Correlation Charts. CRC Press, 2005)
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•Light, sensors, and units
380
770
Visible
 Light: Visible (380‐770 nm)
PAR (400‐700 nm)
700
PAR
Sunlight (280 2 800 nm) 400
Sunlight (280‐2,800 nm)
 Sensors:
Foot‐candle or Lux meter (visible)
Quantum sensor (PAR)
1 ft‐cd = 1 lumen/ft2
Pyranometer (sunlight)
1 lux = lumen/m2
 Units:
1 ft‐cd = 10.76 lux
f d
l
ft‐cd or lux
µmol/(m2*s) or mol/(m2*d) (recommended)
i.e., instantaneous or integrated (DLI)
W/m2 (note: radiant Watt, not electric Watt)
•Preferred light sensors (horticultural applications) Quantum sensor
(400‐700 nm)
measures PAR
measures PAR
Pyranometer
(280‐2,800 nm)
measures solar radiation
measures solar radiation
http://www.envcoglobal.com
http://img.directindustry.com
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• Daily light integrals for Newark, NJ
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
Average
70
Daily Total Radiation (mol/m²d)
60
50
40
30
20
10
0
0
60
120
180
240
300
360
Julian Date
Data source: National Renewable Energy Laboratory
• Average daily light integrals
Dr. Jim Faust, Clemson University
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6/10/2014
• Supplemental lighting (promote photosynthesis)
Benefits:
 Improves crop production (quality, duration)
 Improves crop timing
Improves crop timing
But:
 Impacts other crop production systems, e.g.:
 Environmental control
 Irrigation and fertilization
I i ti
d f tili ti
 Increases capital investment
 Increases overall greenhouse energy use
•Inverse square law
 Light intensity is inversely proportional to the square of the distance from the source
100%
25%
11%
http://imagine.gsfc.nasa.gov
6%
4%
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• Common supplemental light sources:
 Incandescent (photoperiod control)
 Fluorescent (growth and germination rooms)
 High Intensity Discharge (HID):
 High Pressure Sodium (HPS), yellowish light
 Metal Halide (MH), white light
 Light emitting diode (LED), new technology (R&B)
 MH compared to HPS: MH compared to HPS:
 More blue light (plant development)
 Shorter lamp life (6,000 versus 16,000 hrs)
 Less efficient (25% versus 30%)
Incandescent (photoperiod) lighting
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• Photoperiod lighting
with LEDs
Image courtesy of Philips Lighting, http://www.lighting.philips.com
• Fluorescent
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• LED lighting in a multi‐tier germination facility
Image courtesy of Philips Lighting, http://www.lighting.philips.com
• High
High‐‐pressure sodium
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• Mixed mode: Metal halide and high
high‐‐pressure sodium
• LED lighting
(horizontal arrays
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• LED lighting
(vertical arrays)
•Spectroradiometer
7
Intensity (µmol/(m²²s))
6
5
4
3
2
1
0
300
350
400
450
500
550
600
650
700
750
800
850
Wavelength (nm)
http://www.apogeeinstruments.com
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•Spectral output of various lamps
1.0
1.0
INC
MH
0.8
Normalized P
Photon Flux
Normalized P
Photon Flux
0.8
0.6
04
0.4
0.2
0.0
0.6
04
0.4
0.2
0.0
350
400
450
500
550
600
650
700
750
800
350
400
450
500
Wavelength (nm)
600
650
700
750
800
1.0
1.0
HPS
Blue LED
0.8
0.8
Normalized Photon Flux
Normalized Photon Flux
550
Wavelength (nm)
0.6
0.4
0.2
0.0
Red LED
0.6
0.4
0.2
0.0
350
400
450
500
550
600
650
Wavelength (nm)
700
750
800
350
400
450
500
550
600
650
700
750
800
Wavelength (nm)
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• Integrating sphere (ø 76” or 2m)
(Ulbricht sphere)
Lamp under test (DUT)
Baffle
Detector
Auxiliary lamp
Evaluates self‐absorption characteristics of DUT
Spectral radiant flux
Units: W/nm
4 geometry
4π
Spectroradiometer
 Inside of the sphere reflects and uniformly diffuses light (the surface is considered Lambertian; coated with a BaSO4 compound)
 Test lamp surface area should be <2% of sphere surface area
 Maximum test lamp characteristics: 51” (1.3 m) long, 5,000 W power
• Questions regarding horticultural applications:
 Testing compliant with LM‐79, LM‐80?
Q: PAR instead of visible light measurements?
 L70
(TM‐21 compliant)?
 Spectral output (300‐800 nm)?
Spectral output (300 800 nm)?
 PAR distribution (at a specific mounting height)?
 Conversion efficiency (μmol/J)?
 Experience from commercial installations?
 System warranty?
 Q: Do we need our own ‘Lighting Facts Label’?
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• Multiple light sources
 Sunlight (overhead)
 HPS (overhead)
 LED (intracanopy)
LED (intracanopy)
How best to characterize the plant light
plant light environment? Image courtesy of Philips Lighting
http://www.lighting.philips.com
http://www.optexlighting.com/
Thank You!
Questions?
both@aesop.rutgers.edu
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