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Energy saving in greenhouses based on crop physiology Prof Dr Leo Marcelis Chair Horticulture & Product Physiology Wageningen University, Netherlands. [email protected]
Energy saving in greenhouses based on
crop physiology
Prof Dr Leo Marcelis
Chair Horticulture & Product Physiology
Wageningen University, Netherlands. [email protected]
In greenhouses:
An enormous yield increase
30 years:
Yield doubled in tomato
Where is the limit?
Doubling possible!
Energy consumption dropped
0
20
40
60
80
100
1980 1990 2000 2010
Yie
ld (
kg
m⁻² y
r⁻¹ )
Year
Tomato +113%
Sweet pepper +90%
Cucumber +35%
In 30 years yield doubled.
Which part due to breeding?
2
4
6
8
10
To
mat
o h
arv
est
(kg
m-2
)
1940 1960 1980 2000
year of cultivar release Higashide & Heuvelink, 2009
0.9% per year (27% in 30 years)
Genetic improvement tomato due to
- higher photosynthesis
- lower light extinction
Yield = Total biomass production Assimilate partitioning
( = Harvest Index)
Light use efficiency
Light absorption
Light extinction Leaf photosynthesis
Leaf Area Index
Concept for energy saving
Next generation cultivation (‘The new way of growing’)
Ambition
● 40-50% energy saving
● Same yield and quality
● Modular set-up
Next Generation cultivation
Insulation
Follow nature
De-humidify by controlled inlet air
Humidification
Heat harvest= cooling
Greenhouse coverings
Maximize light transmission
Diffuse light
Low energy loss
Next Generation cultivation
Insulation
Follow nature
De-humidify by controlled inlet air
Humidification
Heat harvest= cooling (aquifer)
Temperature control
Strong dependence radiation
● 1 ˚C lower base heating temperature
● 2,5 ˚C stronger light effect
Larger difference heating and ventilation setpoint
Temperature integration (3d, 5˚C d) 1m3
3,2 m3
saving
Next Generation cultivation
Insulation
Follow nature
De-humidify by controlled inlet air
Humidification
Heat harvest= cooling (aquifer)
Inlet outside air for dehumidification
droge warme lucht
Luchtbehandelingskast (10 per ha)
Aanzuigbuis kaslucht
Buitenlucht
aanzuiging
Air treatment unit
Dry warm air
Sucking outside air
More homogenous air humidity
Therefore higher humidity is possible
Screens kan be kept closed longer
Window opening in greenhouses
Opening ventilation windows for cooling and dehumidification
loss of energy and CO2 and water vapour
Beneficial to keep them more closed
From macroclimate to microclimate
(from greenhouse climate to phylloclimate)
3-way interaction:
climate – plant architecture - disease
Vertical temperature gradients
Top
Middle
Low
Floor
Hour of the day
Cooling from below
Air
tem
peratu
re (
˚C
)
Cooling from below: strong temperature gradient
No effect on plant development and growth when temperature at top is maintained
Slightly larger fruit size
From: Qian et al. J. Hort. Sci (2015)
Plant temperature: non uniform
From: Savvides, van Ieperen, Dieleman, Marcelis,
Plant Cell Environm (2013)
Plant temperature: non uniform
From: Savvides, van Ieperen, Dieleman, Marcelis,
Plant Cell Environm (2013)
Meristem temperature & the aerial
environment
-3
-1
1
3
45 60 75 90
Tm
eris
tem
– T
air (o
C)
RH (%)
Day
45 60 75 90
RH (%)
Night Cucumber Tomato
Relative Humidity (%) Relative Humidity (%)
From: Savvides, van Ieperen, Dieleman, Marcelis,
Plant Cell Environm (2013)
Leaf initiation rate & bud temperature
Tbud/Tplant
Savvides, et al. Planta (2016)
Plant phenotype
in relation to
apex temperature 30cm
26oC
22oC
18oC
18oC
18oC
18oC
Apical bud temperature
Air temperature (ºC) ``
Savvides, van Ieperen, Dieleman, Marcelis,
Plant Cell Environm (2017)
What is an optimal leaf area?
0
1
2
3
4
5
6
7
8
9
0 100 200 300 400
Tijd (dagen na planten)
LA
I (m
2 p
er
m2)
Time (days after planting
Sweet pepper
What is an optimal leaf area?
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8
Ligh
t In
terc
ep
tio
n (%
)
Leaf Area Index (m2 m-2)
What is the contribution of different leaf layers?
(layer 1 = bottom, layer 5 = top; LAI >6 )
Lower layer: photosynthesis stronger reduced
than transpiration
Crop transpiration
0
50
100
150
200
17-6 16-8 15-10
Date
mm
ol H
2O
m-2
leaf day
-1
5
4
3
2
1
Crop net photosynthesis
-100
100
300
500
700
900
17-6 16-8 15-10
Date
mm
ol C
O2 m
-2le
af day-1
5
4
3
2
1
What is optimal leaf area?
Most of the light captured at LAI=3-4
● Further increase in LAI
● not much more photosynthesis
● Transpiration keeps increasing
● High air humidity, in particular inside canopy
● Increased maintenance respiration?
● Formation of leaves costs assimilates
Removal of young leaves Fraction of assimilates to fruits: 7 7 _____________ = 0.7 __________ = 0.77 (7+1+1+1) (7+1+1)
Yellow numbers inside leaves and truss = ‘sink strength’
10%
10%
10%
1
1
1
7 70%
11%
11%
1
1
7 77%
Simulated cumulative fruit and total dry weight, fraction partitioned to the fruits and average LAI
LAI was not affected as old leaves were removed every time LAI>3 consequently total plant dry weight (vegetative + generative) was not affected
Treatment = removal of young leaves
___________________________________________________ Treatment DWfruit Fraction (leaf removal) (kg m-2) fruit/total ___________________________________________________ Control 2.92 0.69 1 out of 6 3.01 0.71 1 out of 3 3.11 0.74 ___________________________________________________
Leaf picking strawberry
Treatment LAI (m2 m
-2) Total Biomass (g DM/plant)
Fruit Yield (g/plant)
Fraction partitioned to fruits
Reference 3-4 81 a 430 a 0.50 a
Young leaves removed 2.5 73 a 465 b 0.59 b
Old leaves removed 2.5 436 a
From: Venner &
Marcelis, unpublished
Conclusions
Next generation cultivation
● Insulation, flexible temperature, dehumidify
From macro to micro climate
Leaf formation: often too much
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Thank you for
your attention !
Course on lighting:
7- 9 Feb 2018
12-14 Feb 2018
Student Challenge
“Design the Ultimate
Urban Greenhouse”
WWW.HPP.WUR.NL
