Canadian Greenhouse Conference, 5 October 2016, Niagara ...€¦ · Light transmission and...
Transcript of Canadian Greenhouse Conference, 5 October 2016, Niagara ...€¦ · Light transmission and...
Light transmission and distribution in vegetable greenhousesCanadian Greenhouse Conference, 5 October 2016, Niagara Falls, Canada
Dr. Silke Hemming, Wageningen University & Research Centre
Light is (almost) never too much:
yield increase per% light increase
Crop % Yield increase
Lettuce 0.8Radish 1Cucumber 0.7−1Tomato 0.7−1Rose 0.8−1Chrysanthemum 0.6Pointsettia 0.5−0.7Ficus benjamina 0.6
Source: Marcelis et al., 2006
Diffuse light
Potential diffuse light in different climates
Amount of direct / already diffuse light varies in different climates
Cold winter climate e.g. The NetherlandsMild winter climate
e.g. Mediterranean (Semi-)arid climate
e.g. Middle-East
Increase potential of diffuse coverings
Hemming et al. (2008)
Diffuse light – crop effects
Li (2014)
Horizontal light distribution at crop level
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Pad
Lich
tinte
nsite
it (%
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Lengte rij ( cm )
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it (%
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Reference
Diffuse71
Dueck et al. (2012)
Diffuse light – crop effects
Li (2014)
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Cro
p he
ight
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]
Light interception [%]
April 25th, 2006
ClearDiffuse
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Cro
p he
ight
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Light interception [%]
May 3rd, 2006
ClearDiffuse
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Cro
p he
ight
[cm
]
Light interception [%]
May 23rd, 2006
ClearDiffuse
Vertical light distribution in crop - cucumber
Hemming et al. (2007)
Diffuse light – crop effects
Li (2014)
Photosynthesis net - high-wire cucumber
Dueck et al. (2009)
Photo-inhibition - tomato
Dueck et al. (2012)
Diffuse light – crop effects
Li (2014)
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12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Weeks
Cum
ulat
ief p
rodu
ctie
(kg/
m2)
Hoog diffuusLaag diffuusControle
Crop yield - cucumber high-wire
Diffuse light: 9% higher cucumber production (crop planted in March)
+9.2%
+6.5%
Weeks
Prod
uctio
n(k
g m
-2)
High diffuse
Low diffuse
Control
Dueck et al. (2008)
Diffuse light sweet pepperca. 5% more yield
Diffuse light cucumber4-10% more yield
Hemming et al. (2006, 2008)
Diffuse light tomato8-10% more yield
Plas
tic f
ilms
Increased light scattering
Gla
sses
Diffuse light
Optical properties – light quantity
Light (PAR)
Transmission
Reflection
Absorption
increases
decreases
Covering material
1 – Absorption – Reflection = Transmission
Measurement light quantity
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Wageningen UR TransvisionIntegrating Sphere for
hemispherical light transmission measurement
∫∫
∫∫= 2/
0
2
0
2/
0
2
0
)cos()sin(),(
)cos()sin(),(),(
pipi
pipi
HEM
ddI
ddITT
φθθθθφ
φθθθθφθφ
Transmission τ [%]
Angle of incidence 𝜭𝜭i [o]
Measure angular and hemispherical light transmissionNOT perpendicular light transmission
Transmission
Geometrical distribution
Optical properties – light geometricaldistribution
Light
Diffuse structure
Covering material Diffuse pigments
Light (PAR)
Materials and Methods - Equipment
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Radiant IS-SA Imaging Sphere for Scatter and Appearance
Measurement at Wageningen UR Lightlab
Measure Haze or even better BTDF scattering
Diffuse coverings – plastics
Plastic films
Hemispherical light transmission τh vs. haze η
y = -0.16x + 85.6R² = 0.41
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hem
isp
her
ical
tra
nsm
issi
on [
%]
haze [%]
Diffuse coverings - PE/EVA plastic films
Code Material Hazeη
Hemisphericaltransmission
τh
PK14A Clear film AD 23 81.3
PK14C Normal film 49 77.1
PK14D Normal film AD 60 74.7
PK14B Extra diffuse film 97 68.9
Amount of lightAmount of scattering
Light Diffusing Materials – high η, high τh
0 10 20 30 40 50 60 70 80 90 100
HDPE high diffusion,80µm BR
HDPE mediumdiffusion, 80µm BR
ETFE high diffusion,100 µm AS
ETFE mediumdiffusion, 80 µm AS
haze hemispherical transmission
Diffuse coverings – glasses
Glasses
Diffuus en anti-reflectie: transmissie
material hazehemispherical transmission
A 0 0 84.4A 0 AR 87.1A 0 ARAR 90.2A LH 20-30 83.6A LH AR 86.2A LH ARAR 89.2A HH 70-80 79.7A HH AR 82.2A HH ARAR 84.3
+2.5-3%per side
Results - glass
Material
Cod
e
Lig
ht
tran
smis
sion
per
pen
dic
ula
r
Lig
ht
tran
smis
sion
hem
isp
her
ical
Haz
e
F-sc
atte
r
τp τh η ΦTraditional greenhouse glass PLA09 90.4 82.7 4 0Clear glass* R0 97.4 90.2 4 0Matt/matt glass low diffusion* SG20 95.9 89.2 20 4Matt/matt glass medium diffusion* SG45 95.3 87.5 46 22Prismatic glass high diffusion* SG80 95.2 84.3 78 54Etched glass high diffusion* DA80 98.0 86.0 83 59Etched glass extra high diffusion* DA95 97.9 81.7 94 79Paraboloid glass extra high diffusion SG95 75.0 69.1 97 82Motheye microlens extra high diffusion NO12J 76.6 70.1 100 98Lambertian diffusor L100 44.6 40.4 100 100
* with anti-reflection coating
Results - glass
Material
Cod
e
Lig
ht
tran
smis
sion
per
pen
dic
ula
r
Lig
ht
tran
smis
sion
hem
isp
her
ical
Haz
e
F-sc
atte
r
τp τh η ΦTraditional greenhouse glass PLA09 90.4 82.7 4 0Clear glass* R0 97.4 90.2 4 0Matt/matt glass low diffusion* SG20 95.9 89.2 20 4Matt/matt glass medium diffusion* SG45 95.3 87.5 46 22Prismatic glass high diffusion* SG80 95.2 84.3 78 54Etched glass high diffusion* DA80 98.0 86.0 83 59Etched glass extra high diffusion* DA95 97.9 81.7 94 79Paraboloid glass extra high diffusion SG95 75.0 69.1 97 82Motheye microlens extra high diffusion NO12J 76.6 70.1 100 98Lambertian diffusor L100 44.6 40.4 100 100
* with anti-reflection coating
Results- BTDF glass
2D plot of calculated angular energy distribution E(𝜃𝜃𝑡𝑡) based on measured BTDF of different glasses
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η=94%
η=97%
η=100%
η=100%
Φ=79%
Φ=82%
Φ=98%
Φ=100%
Conclusions diffuse materials
Measure hemispherical light transmission & haze & Fscatter
Covering materials with higher light scattering increase production (at same light transmission!)
Materials with different scattering distribution (Fscatter) are available, choose right material for crop
Covering materials with significantly reduced hemispherical transmission can cause production decreases (if light is limiting factor)
Other materialsScr
eens
Increased light scattering
Coa
tings
Thank you for your attention!
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