Improving greenhouse production efficiency

Ep Heuvelink & Leo Marcelis Horticulture & Product Physiology group Wageningen University, The Netherlands Ep.Heuvelink@wur.nl

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