New Generation Growing

Review of practical experience and results of trials in different cut flower crops

Marco de GrootCrop consultant Gerbera and Alstroemeria

marco@floriconsultgroup.nl

What is New Generation Growing ?

• The aim of Kas als Energiebron (Greenhouse as Energy Source), the innovation and action programme for the greenhouse horticulture sector, is to reduce greenhouse horticulture CO2 emissions by 2 to 3% per year.

• This must be achieved through energy-saving innovations and the use of sustainable energy.

• LTO Glaskracht Nederland (Growers Association) and the Ministry of Economic Affairs are working together on this programm.

What is New Generation Growing ?

The new cultivation (HNT) is literally a new way of growing and climate based on plant physiology and physics.With improved and new knowledge of climate and grow processes in a greenhouse, a better management of greenhouse climate.

Application of knowledge in order to:• Minimize difference in greenhouse air temperature• Minimize differences in plant temperature • Save energy (gas and electricity)• Improve crop health and quality

New Generation Growing

• A particular feature of the new generation cultivation is that it starts with the acquisition of new insights and learning new behaviors, rather than invest in new greenhouse hardware or equipment.

• Additionally, energy saving is not an end in itself, but a logical consequence of optimizing the growth environment for the plant, provided that this is properly addressed.

New Generation Growing

An active and vigorous micro climate with low energy costs can only be achieved by applying 4 measurements simultaneously:• Forced air movement around the plant• Prevention of temperature differences (macro and micro)• Elimination of moisture• isolate better with (double) energy screens

New Generation GrowingSince 2007 growers are using the tools of the new generation growing:- Many growers have attended a course of NGG to understand

physics of plant and greenhouse climate better- All growers are using this knowledge together with the help of

consultants- Greenhouse climate software is adapted based on those new

principles

New Generation GrowingThe proper use of energy screens is a major tool in implementing NGG- Use of screens with better insulating characteristics

- Black out screens 77 % energy saving - Transparent energy screens 20 % as a 2nd energy screen

- Use of a smaller gap in energy screens to reduce temperature differences in greenhouse

- Use of outdoor temperature as major factor for gap strategy of energy screens and not indoor temperature or RH indoor

- Outdoor temperature is more stable than indoor temperature- Outdoor temperature and absolute humidity are related to each other

New Generation GrowingHumidity control is essential for optimum results in NGG- Absolute humidity (AH) in greenhouse (in gram/m3) is often higher

than outside the greenhouse- Relative humidity (RH) is not a good unity to control humidity in

greenhouse- Ventilation is best and most efficient way of reducing RH in the

greenhouse- Closing screens and ventilation above, is the way to control AH at

night

IrridiationA clear sky, at a high irradiation, the plant temperature at the top of the crop can drop up to several degrees below the air temperature of the greenhouse, making the evaporation is stagnant and moisture condenses easily.

Advise: the use of an energy/thermal screen before sun set prevent the irradiation and so a decrease of plant temperature.The plant temperature stays more equal to the greenhouse temperature (cooling down is more steady and more even)The plant grows better and also get more nutrients. This is especially important for the uptake and transportation of calcium

Irridiation

Pyrgeo meter to measure negative radiation (0 till – 160 Watt)Irridiation is present 24 hrs a dayDegree of cloud cover determines level of irridiation

Irridiation

• Until a few years unknown climate factor• Research shows that irradiation could cause many quality

problems:– Cracking stems– Botrytis– Leaf scorch

• More intensive use of energy/shade screens can reduce the factor of irridiation by closing screens before sun set or turning off lights

• Plant parts in top of the crop, heat up the fastest but also cool down the most quick (when radiation of sun disappears)

Irridation• Calcium uptake mainly depends on temperature of different plant

parts (leaves, growth points and head)• Warmest parts of plants attract most to Ca• Coolest parts of plants (head/growing points) attract the least• By more intensive and early use of screens, quick plant cooling

down can be reduced• As a result, better absorption of Ca in youngest parts of plants• Less problems with leaky cells in climate transitions• Less issues with cracking stems, Botrytis, leaf issues, rotting flowers

Greenhouse climate cloudy day

Greenhouse climate clear sky at night

Greenhouse climate winter day

Greenhouse climate winter night

• Goal: develop and test energy efficient cultivation concept for smaller, relatively cold Ornamentals such as Alstroemeria, freesia, amaryllis and Carnation

• Reducing heat demand :• intensive screens (dual screen) with air movement• temperature integration• Negative DIF

• Other• air humidification, soil cooling with heat pump circuit • Change to hydroponic cultivation

Alstroemeria

- Objective: • Reduction of gas consumption with 40%• Equal or higher production• Improving micro-climate (lower AH)• Less problems with scorch in leaves

•Results:• Reduction of gas consumption with 37%• Equal production• Improved micro-climate (lower AH in crop)• Less problems with moisture leaves• Better absorption Ca at improving microclimate by dehumidifying

greenhouse air

Alstroemeria

Alstroemeria

Schematic representation of a air circulation system with tubes in beds growing on substrate at Alstroemeria. The hoses are attached to the lower wire mesh.

Alstroemeria

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Weeknummer

Gas

verb

ruik

per

wee

k (m

3/m

2)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Cum

ulat

ief g

asve

rbru

ik (m

3/m

2)

Energiezuinig Referentie Energiezuinig cumulatief Referentie cumulatief

Resultats: Extra transparent LS10 screen as well as light reducing screens (assimilation) 37% energy saving Less quality problems with leaves and stems or flowers due to high humidity or high

irradiation such as moisture leaves of cracking stems

Alstroemeria

Vertical fans and baffles

Gerbera

Gerbera

Vertical fansPractical experiments GerberaObjective Gerbera

• Intensive use screens with multiple towels without Botrytis• Diminishing of vertical temperature differences• Reduce energy consumption when heating in the morning

Resultats Gerbera• Energy saving 6 m3/m2 (25%)• Less minimum pipe• Vertical temperature distribution is improved• No adverse consequences to the cultivation

Gerbera

The main conclusions are:- Use of dehumidification with outdoor air or with Ventilation Jets:

- screens can stay closed longer (transparent screens)- the use of a screen crack can be reduced and postponed.

- The achieved savings with tubes underneath: - between 9% and 17%

- The achieved savings with Ventilation Jet + Vertical Fans: - between 20%

- Tubes from underneath vs above: - crop evaportion is stimulated- Less saving of energy - Less effect on RH or HD around flowers

Vertical fans

Systems in greenhouse flowers

• Ventilation Jet / Nivolution

• Capacity 14 m3/m2/hr• With extra use of vertical fan• Also for existing greenhouses, 15-18 % saving in nat. Gas equivalent

Systems in greenhouse flowers• Tubes from above

• Capacity 5 m3/m2/hr• Heat exchange unit installed in the greenhouse wall• No use of vertical fan, natural air flow • Also for existing greenhouses: 12 % saving in nat. Gas equivalent

Systems in greenhouse flowers

• Tubes from underneath

• Capacity 5 m3/m2/hr• Opening “10 to 2” upright • Also for existing greenhouses, 10 % saving in nat. Gas equivalent

Results for greenhouse flowers• Energy savings for all crops

– Better understanding greenhouse climate– Less minimum pipe– More active ventilation

• increased use of energy screens:– Less Botrytis (petals and buds)– Less scorch in leaves– Better uptake of Ca

• with low air speed:– Less mildew (but more with more aif flow)– More equal greenhouse climate– Less differences in greenhouse temperature (hot and colder spots)

New Generation GrowingNGG is not:- Using less lighting: results of trials are not positive.

- Lighting with HPS lights is very efficient for crop growth and crop heating- Less lighting means more use of pipe energy which is less effective- Nett more energy with less lighting hours

- Investing in just hardware for dehumidification - Experience in The Netherlands proves that implementation of knowledge of

NGG already resulted in nett 15 % energy saving per m2- Implementation of knowledge has reduced energy per flower with more than

25 %

Monitoring greenhouse climate eveness

Web based analyses to see a 24 hrs development on long term in a greenhouse compartment

Monitoring greenhouse and plant climate

Remote temperature and humidity sensors to measure differences (horizontaland vertical) in a greenhouse compartment

New features

Thermal cameras:

Radiation app

Examples:

Alstroemeria nursery De Hazekamp: https://www.youtube.com/watch?v=mmRm58OT-uU

Gerbera nursery Klondike Gardens:https://www.youtube.com/watch?v=mmTbuLUZu9c