How to obtain a high tomato yield100 kg per m2 per year or more ?

Ep HeuvelinkHorticultural Supply Chains, www.hpc.wur.nl/uk

Ep.heuvelink@wur.nl

Plant Sciences Group, Wageningen University

1st Agriconference on Tomatoes from Morocco9 December 2009, Agadir, Morocco

Yield development (Netherlands)

Sweet pepper

Cucumber

Tomato

+ 96%

+ 117%

+ 34%

Sweet pepper

Cucumber

Tomato

0

20

40

60

80

1980 1990 2000 2010

Year

Yie

ld (

kg m

-2)

+107%

+94%

+125%

Cucumber

Tomato

Sweet PepperTomato in Morocco

(Kwantitatieve Informatie voor de Glastuinbouw (KWIN 2008))

What factors are important for high yield ?� Greenhouse technology (e.g. light transmission)

� Cultivation techniques (e.g. high wire system, rootstocks)

� Modern cultivars

� Greenhouse climate control(temperature, CO2, humidity, supplementary light)

� Most recent developments(semi~closed greenhouses, diffuse light)

Also important is:

� High education level of growers

� Moderate climate: winters not too cold, summers not too hot

Nor

thNor

thse

ase

a

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 !

Cultivation techniques� High wire system; same plant almost year-round� Long season, up to 50 weeks; no production gaps

Cultivation techniques� Stonewool + drippers; better control of root environment

� Extra stems in summer (2.5 plants m-2 ￫ 3.8 stems m-2)� Use of grafted plants (cultivar on rootstock)

StonewoolStonewool

CubeCube & Slab& Slab

0.0 1.0 2.0 3.0 4.0

Leaf Area Index

0.0

0.2

0.4

0.6

0.8

1.0F

ract

ion

light

inte

rcep

ted

y = 1 - e -k LAI

Influence of Leaf Area Index (LAI) on the fraction of light intercepted

by a tomato crop (k = extinction coefficient = 0.8)

LAI: mLAI: m22 green leaf area per mgreen leaf area per m22 ground area)ground area)

Measured LAI throughout the season for tomato(measurements at modern commercial farms)

0

1

2

3

4

5

50 100 150 200 250

Day of year

Leaf

Are

a In

dex

(m2 m

-2)

Year 2003

Year 1990

� Now much higher than in early nineties, probably becauseextra side shoots are retained from spring onwards + rootstock?

Effect of cultivar on tomato yield (Spring crop)

40% yield increase since 1950, mainly because of higher light use efficiency

Greenhouse climate

� Modern climate computers makemore accurate control possible

� Important factors: temperature, CO2, humidity

• Heating

→ boiler + hot water pipes

• Cooling

→ vents in roof

→ fog cooling

→ roof cooling

Production techniques in modern greenhouses (1)Greenhouse climate: temperature

Fruit weight (dry mass) and

fruit growth period (FGP) tomato

Temperatuur (oC) Gewicht (g) Uitgroeiduur (d)17 4.8 7419 4.3 6321 3.2 5623 2.7 50

Source: A.N.M. de Koning

At lower temperature harvest starts later and fruits are more heavy

Temperature (oC) Fruit weight (g) FGP (d)

High temperature stress (tomato)

� No effect on total growth

� Poor fruit set

� Cause: bad pollen, poorly released 0

4

8

12

16

Controle Hoge Temp

Aan

tal g

ezet

te v

ruch

ten

p

er p

lan

t

0

20

40

60

80

100

Controle Hoge Temp

Lev

end

e st

uif

mee

lko

rrel

s (%

)

Control: 28/22oC D/N; High temp. 32/26oC

Source: Sato et al. 2006

� Questions like: is 1 h 36oC a problem? Or: Is 1 h 38oC same as 10 h 36oC?

Not yet clear !

Control High temp.

Control High temp.Via

ble

polle

n (%

)N

umber

of se

t fr

uits

per

pla

nt

AlsoAlso tootoo low low temperaturestemperatures limit fruit set !limit fruit set !

Greenhouse climate: CO2

� Natural gas for heating: flue gasses for CO2

� Pure CO2

Source: E. Nederhoff

Rule of thumb for CO2 effect:

For each 100 ppm increase in CO2 % increase in growth can be calculated as

1500 × 1000

CO2 × CO2

� From 350 to 450 ppm: 12% growth increase

� From 600 to 700 ppm: 4% growth increase

� From 1000 to 1100 ppm: 1.5% growth increase

� But from 350 to 250 ppm: 19% reduction in growth!!

Source: E. Nederhoff, 1994

Greenhouse climate: High humidity

Deficit < 0.2 kPa (<1.5 g/m3) or RV >94% at 25°C

� Too low Ca in leaves KK> smaller leaves KK> less light interception KK> less photosynthesis

� Pollination less optimal (without bumble bees)

� Higher disease risk (botrytis)

� Higher risk fruit “disorders”(cracking)

Greenhouse climate: Low humidity

Deficit > 1 kPa (>7.5 g/m3) or RH < 70% at 25°C

� Water stress in plant

� Stomata close

� Cell elongation reduced KK> smaller, thicker leaves

� Less photosynthesis

� Reduced water content fruit

� BlossomKendKrot (BER)

New trends: semiKclosed greenhouse

AirAir--conditioned (active cooling) so vents more closedconditioned (active cooling) so vents more closed

Too high temperatures can be avoidedToo high temperatures can be avoided

Higher COHigher CO22 levels levels �� higher yieldshigher yields

In the Netherlands: Winter: 80% diffuse radiationSummer: 60% diffuse radiation

Advantages of diffuse radiation:� More even distribution of light (horizontally; no shadows)� Light penetrates deeper in the crop� Lower risk of light saturation� Mild micro-climate

New trends: Diffusing cover materials

Control Low diffuse High diffuse

Haze 0% 30% 70%

Transmission 83% 83% 80%

New trends: Diffusing cover materials

Experiment with cucumber crop: Bleiswijk 2008, Netherlands

Diffuse light: 9% higher cucumber production

(crop planted in March)

0

25

50

75

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 diffuus

Laag diffuus

Controle

+9.2%

+6.5%

Weeks

Pro

duc

tion

(kg m

K2)

Source: T. Dueck

High diffuse

Low diffuse

Control

Conclusion: main reasons for high tomato yield� Almost yearround cultivation

(high wire system, extra stems in summer, rootstocks)

� Cultivation out of soil

� Hightech greenhouses (high light transmissivity,good temperature and CO2 control)

� High yielding cultivars (breeding)

Future developments: semiKclosed, LED lights

Thank you for your attention

The following colleagues contributed to this presentation:

Menno Bakker, Silke Hemming, Leo Marcelis, Anke van der Ploeg