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Improving greenhouse production efficiency
Ep Heuvelink & Leo Marcelis Horticulture & Product Physiology group Wageningen University, The Netherlands [email protected]
Some figures on Dutch greenhouse horticulture sector of great economic importance
About 120.000 people employed Added value greenhouse horticulture: € 5.6 x 109 9.500 ha 0.5% of agricultural land area Production value is 22%
of agrocomplex
70-75% greenhouse produce is exported Mean gross income 600 000 €/ha Mean net return 60 000 €/ha
Very high yields, still increasing
Yiel
d (k
g m
-2 p
er y
ear)
Yield has doubled over the past 30 years
Which factors are important for high yield ?
Greenhouse technology (e.g. light transmission)
Cultivation techniques (e.g. soilless)
Modern cultivars
Greenhouse climate control (temperature, CO2, humidity, supplementary light)
Obtain high light transmissivity of the greenhouse
1% more light ≈ 1% more yield Greenhouse transmissivity in 1980 ≈ 65%
nowadays ≈ 78% represents about 20% yield increase
Large glass panes, small construction parts, white ! Cleaning of cover !
Component analysis: higher fresh fruit yield in modern cultivars
Total yield of fresh tomatoes (kg m-2)
Fruit dry matter content (kg kg-1)
Total dry matter (kg m-2) Fraction to fruits (kg kg-1)
Total yield of dry tomatoes (kg m-2)
Total yield of fresh tomatoes (kg m-2)
Fruit dry matter content (kg kg-1)
Total dry matter (kg m-2) Fraction to fruits (kg kg-1)
Light use efficiency (g MJ-1)
Fraction of light intercepted (MJ m-2)
Sink strength of fruits
No. of fruits
Truss appearance rate No. of fruits per truss
Total yield of dry tomatoes (kg m-2)
LAI (m2 m-2) Photosynthetic rate (g m-2 s-1)
Light extinction coefficient
Component analysis: higher fresh fruit yield in modern cultivars
Better varieties: 0.7% yield increase per year (Expt. 1: August-November; Expt. 2: June-December)
Average yield Sonatine, Calypso and Encore: 6.3 resp. 12.0 kg/m2
P=0.003
Total yield of fresh tomatoes (kg m-2)
Fruit dry matter content (kg kg-1)
Total dry matter (kg m-2) Fraction to fruits (kg kg-1)
Light use efficiency (g MJ-1)
Fraction of light intercepted (MJ m-2)
Sink strength of fruits
No. of fruits
Truss appearance rate No. of fruits per truss
Total yield of dry tomatoes (kg m-2)
LAI (m2 m-2) Photosynthetic rate (g m-2 s-1)
Light extinction coefficient
Component analysis: higher fresh fruit yield in modern cultivars
Tomato yield doubled over past 30 years; 20-25% results from improved cultivars
Improved Light use efficiency, because of higher leaf photosynthesis and deeper light penetration (less extinction)
Greenhouse is key factor to minimize water use
0
20
40
60
Israel & Spain, field
Spain, unheated
plastic "parral"
Israel, unheated
glass
Spain, unheated "parral",
regulated ventilation
Holland, climate-
controlled glass, CO2 enrichment
Holland, as at left, with re-use of
drain water
Holland, "closed"
greenhouse
Wat
er u
se
(litr
e pe
r kg
tom
ato)
From Stanghellini
Source: Stanghellini
Water and Nitrogen (N) efficiency Yearround greenhouse tomato (free drainage)
_________________________________________________________
Soil grown crop Substrate grown crop Water N Water N _________________________________________________________
Addition 12950 2269 9691 1935 Uptake by crop 6700 609 7600 1110 Efficiency (%) 52 27 78 57 _________________________________________________________
Source: Sonneveld
Recirculation: efficiencies above 90%
Energy use: Towards Climate neutral greenhouses
1980 1990 2000 2010
20
40
60
80
100
target 2000 (50)
target 2010 (35)
2020
target 2020 (0) En
ergy
use
inde
x
Closed greenhouse
Reduction in energy use
(up to 30%)
Harvest the excess heat in
summer, store in aquifers and re-use heat in winter
warm cold
warm cold
Cogeneration of heat and power (CHP)
Very efficient use of heat, electricity and CO2
Covers 10% of Dutch national electricity consumption Applied on 7000 ha glasshouses
Temperature integration (sweet pepper)
0
100
200
300
5 10 15 20 25 30
Dry
wei
ght f
ruits
(g/
plan
t)
Time (weeks)
optimaal
standaard
Optimal strategy: average temperature same as ‘control’ fluctuation between 16 and 30oC less ventilation daytime → higher CO2
2.5 m3 less natural gas equal fruit set and yield
optimal control
Crop responds to average temperature, not exact temperature regime
Source: Dieleman et al.
Leaf picking in sweet pepper: reduce energy use without production loss
LAI = Leaf Area Index
Source: Dueck et al. 2006
Energy saving
The application of energy saving measures is limited by the crop and by risks perceived by the growers (e.g. botrytis)
Next Generation Cultivation (‘The New Way of Growing’): 40-50% energy saving
Isolation (e.g. 2 or 3 screens) Follow nature De-humidify by controlled inlet air Humidification Heat harvest= cooling
droge warme lucht
Luchtbehandelingskast (10 per
Buitenlucht aanzuiging
Dry warm air
Sucking outside air
Air treatment unit
Diffusing light Clear results: 5-10% yield increase
Diffuse light: more homogeneous Direct light Diffuse light
Photosynthetic capacity (standard and diffusing glass)
-5
5
15
25
35
0 400 800 1200Licht op blad (µmol PAR/m2/s)
Net
to fo
tosy
nthe
se, (
µmol
/m2/
s)
-5
5
15
25
35
0 400 800 1200Licht op blad (µmol PAR/m2/s)
Net
to fo
tosy
nthe
se, (
µmol
/m2/
s)
High in the crop
Light on leaf (µmol PAR m-2 d-1) Light on leaf (µmol PAR m-2 d-1) Net
pho
tosy
nthe
sis
(µm
ol m
-2 s
-1)
Net
pho
tosy
nthe
sis
(µm
ol m
-2 s
-1) Low in the
crop
Standard
Diffuse
Source: T. Dueck
Diffusing light Clear results: 5-10% yield increase
0
2
4
6
Total horizontal light distribution
vertical light distribution
leaf photosynthesis
LAI
% in
crea
se c
rop
p
ho
tosy
nth
esis
Efficient use of supplementary light
determined by the balance between source (assimilate production) and sink (demand for assimilates) (source-sink balance)
Source/sink ratio during plant development 3 cultivars different in fruit size
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
0 20 40 60 80 100
Sou
rce/
sink
rat
io
Days after planting
Komeett Capricia Sunstream
Large fruit size
Small fruit size
Medium fruit size
LED light more energy efficient (and allow interlighting, spectral control)
● HPS: 1.8 µmol/J ● LED Toplight 2.3 µmol/J (according to companies)
Hybrid lighting – HPS above, LED interlight
Most modern protected cultivation. From greenhouse to factory Most suitable when
High added value (product, marketing concept)
Critical growth stages (e.g. propagation)
Small crops
● Feeding the world is a different story
Lettuce transplant production
Reduce labour demand: robotics and vision: rapid developments for automation
Conclusions
Ever increasing level of control ● In 30 years: yield doubled
Strong reductions in energy use Recirculation in soilless cultures: very high water and
nutrient efficiency Developments in light: diffuse, LED (spectrum, timing,
direction, heat) Labour efficiency: robotics and vision From greenhouse to factory?
Thank you for your attention !
Co-workers Anja Dieleman Tom Dueck Higashide Tadahisa Pornpipat Kasemsap Frank Kempkes Tao Li Cecilia Stanghellini Wim Voogt