retractable roof greenhouse production system

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The Retractable Roof Production System

(RRPS)

The most profitable and sustainable production system for mild and hot climates

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Outline• Video of a retractable roof• Summary of results from INIFAP, Culiacan, Sinaloa

• Impact on harvest season, yields, quality and shelf life

• Video of the impact of the sun on soil temperatures

• How to control the retractable roof

• Specific strategies and best practices which help

growers achieve a 2 to 5 year return on investment.

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When growing in the open field with no roof, the yield, quality, and timing is reduced due to excessive:• cold• heat• rain• wind• insects

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When growing under a stationary greenhouse roof the plants are protected from excessive cold, rain and wind, but the roof covering now causes:• excessive heat in the greenhouse• insufficient light during the early morning and late afternoon• insufficient levels of C02• insufficient transpiration• insufficient water stress• plants to be more susceptible to insects and disease

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The open field and a stationary roof each have both advantages and disadvantages.

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Retractable roofs are designed to allow growers in warm or hot climates to have the best of both the open field and a closed greenhouse.

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Taking advantage of both the natural outdoor environment and a controlled greenhouse

environment allows growers to...

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•Extending harvest seasons in order to realize the higher prices of the shoulder seasons and extend supply season to distributors

•Increasing yields which reduces the fixed costs per case

•Eliminating the supply disruptions due to erratic weather… so that growers never lose a customer

•Growing organically or chemical free in order to achieve higher revenues and lower production costs

•Increasing the shelf life

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This is a result of the growers ability to use the roof to manipulate:

•Light quantity

•Light quality

•Leaf, fruit and soil temperatures

•Humidity

•C02

•Transpiration

•Water stress

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2007

2008

2009

2010

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These DeRuiter 2180 roma tomatoes were transplanted from the same tray at INIFAP on January 20, 2008 in Culiacan.

Pictures were taken April 26, 2008

Retractable Roof Stationary Nethouse Open Field

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The differences in the growing environment changed the balance between leaves and fruit…

By changing the transpiration rate and water stress.Retractable Stationary Net No Roof

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Retractable Stationary Net No Roof

Retractable roof has the optimal balance between leaves and fruit due to optimal transpiration.

Nethouse has excessive vegetative growth and small fruits due to insufficient transpiration.

Open field has a small plant canopy and a few small fruits due to the excessive transpiration outside.

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RetractableStationary NetNo Roof

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Plantation date: January 20,2008 Export Quality Total Cases per hectare

Company- hybrid Production House x- large large medium small Export National Culls Total SalableDeRuiter 2180 Nethouse 278 837 1045 831 2991 2613 3722 5604

  % of total production 5% 15% 19% 15% 53% 47%     

DeRuiter 2180 Retractable Roof 486 2012 2735 1279 6512 5536 5041 12048  % of total production 4% 17% 23% 11% 54% 46%  

 increase in cases in the

retractable roof 208 1175 1690 448 3521 2923 1319 6444

% Increase in the retractable roof 75% 207% 162% 54% 118% 112% 35% 215%   

Company- hybrid Production house x- large large medium small Export National Culls Total Salable

Harris Moran El Cid Nethouse 417 1033 1589 908 3946 2978 3194 6924  % of total production 6% 15% 23% 13% 57% 43%                     

Harris Moran El Cid Retractable Roof 2963 3561 2763 1258 10544 3654 1417 14198  % of total production 21% 25% 19% 9% 74% 26%  

 increase cases in the

retractable roof 2,546 2,528 1,174 350 6,598 676 - 1,777 7,274

% Increase in the retractable roof 611% 245% 74% 39% 167% 23% -56% 105%

75%-611% increase in extra large and a 207%-245% increase in large fruit

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Plantation date: January 20,2008 Export Quality Total Cases per hectare

Company- hybrid Production House x- large large medium small Export National Culls Total SalableDeRuiter 2180 Nethouse 278 837 1045 831 2991 2613 3722 5604

  % of total production 5% 15% 19% 15% 53% 47%     

DeRuiter 2180 Retractable Roof 486 2012 2735 1279 6512 5536 5041 12048  % of total production 4% 17% 23% 11% 54% 46%  

 increase in cases in the

retractable roof 208 1175 1690 448 3521 2923 1319 6444

% Increase in the retractable roof 75% 207% 162% 54% 118% 112% 35% 215%   

Company- hybrid Production house x- large large medium small Export National Culls Total Salable

Harris Moran El Cid Nethouse 417 1033 1589 908 3946 2978 3194 6924  % of total production 6% 15% 23% 13% 57% 43%                     

Harris Moran El Cid Retractable Roof 2963 3561 2763 1258 10544 3654 1417 14198  % of total production 21% 25% 19% 9% 74% 26%  

 increase cases in the

retractable roof 2,546 2,528 1,174 350 6,598 676 - 1,777 7,274

% Increase in the retractable roof 611% 245% 74% 39% 167% 23% -56% 105%

118% and 167% increase in export cases per week compared to a nethouse.

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Variety Production House 26-Apr 3-May 10-May 17-May 24-May 31-May Total

De Ruiter 2180 Nethouse 61 716 398 281 1261 273

2,991

De Ruiter 2180 Retractable roof 1952 705 2155 1231 378 91

6,512

Increase in cases 1891 -11 1757 950 -883 -182 3,521

% increase in the retractable roof 3000% -102% 341% 238% -170% -167% 118%

Variety Production House 26-Apr 3-May 10-May 17-May 24-May 31-May TotalHarris Moran

EL CID Nethouse 269 465 198 1042 995 977

3,946

Harris Moran EL CID Retractable Roof 3123 1711 2113 2598 587 412

10,54

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  Increase in cases 2854 1246 1915 1556 -408 -565 6,598

% increase in the retractable roof 1061% 268% 967% 149% -41% -58% 167%

1061% and 3000% increase in first harvest

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Not only does retractable roof create an increase in the first harvest, size and total yield…

there is also an increase in shelf life.

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Day 2

Retractable

RetractableRetractable Retractable

NethouseNethouse

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Day 4

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Day 20

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•Extending

Day 36Retractable Retractable Retractable

RetractableNethouse Nethouse

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Tomatoes could be sold both for the fresh market and for food service.

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Tomatoes could be sold both for the fresh market and for food service.

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Grape Tomato

2008-2009, Los Mochis

Retractable Flat Roof

Conventional Nethouse

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Yield INCREASE in First Year of Production Retractable roof vs Open field: 135%

Retractable roof vs Nethouse: 60%

Open Field Net House Retractable Flat Roof

Yield lb/ha 85,000 125,000 200,000

Yield kg/ha 38,590 56,750 90,800

Grape Tomato Harvest2008-2009, Los Mochis Mexico

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Peppers in the retractable roof have a natural tendency to produce more fruit and less leaves than a conventional greenhouse or nethouse

Low transpiration rates cause low levels of water stress causing minimal fruit and excessive vegetative growth

Medium transpiration and water stress causes a natural balance between leaves and fruit.

Open Field Stationary roof Retractable roof

High transpiration cause high water stress which causes plants to grow slowly but have extensive reproductive growth (many fruits)

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The pepper and cucumber crops have been grown in the same soil for 12 years!

13 years in the same soil with the same roof covering

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The roof can be retracted when it is raining to:

• irrigate the crops with water which has a low EC thereby saving water.

• reduce the EC of the soil media by leaching salts which could allow growers to continue to grow in the ground.

The most frequent question about growing in the retractable roof production system is…

What about the insects?

8 years of experience have proven that insect pressures are easier to manage in the retractable roof… for two main reasons…

1.Insects prefer to lay eggs on weak or sick plants and plants grown in a retractable roof are stronger2.Cuticles on leaves are thicker than under a stationary roof due to the higher UV and transpiration rates.

Whitefly are present but there are no eggs or nymphs

And no virus is present

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Stationary insect net

Leaves from plants grown in a retractable roof have a thicker wax cuticle compared to those from a plant grown in a stationary roof.

Retractable Roof

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The sun leaf is much thicker and has multiple layers of palisade cells. (Taiz and Zeiger)

A thicker wax cuticle helps plants protect itself from excessive transpiration and helps improve the plants ability to naturally defend itself against insects and disease.

Leaf in grown in full sun

Leaf grown in shade

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The majority of the insect and disease control inside a retractable roof can be accomplished using soap and garlic.

Open Field

Retractable Roof

In 2007, Dr. Triana Maranon managed a trial in Los Mochis Mexico comparing beefsteak tomatoes grown in the open field and a retractable roof.

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The following chart are the % losses due to disease and insects in the trial.

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Disease and insect pressure was also lower in the retractable roof than in a nethouse in a trial done at INIFAP in Culiacan in 2008-09.

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Growing organically can be easier in a retractable roof greenhouse since they are a very effective tool to naturally:

• improve plant health and resistance to disease and insects• use the sun to sterilize the environment• allow insect populations to have both pests and their natural predators• increasing transpiration to allow plants to more easily absorb and distribute natural fertilizers• reduce root problems • prevent foliar diseases

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How do you know when to close or retract the roof?

What is the best sensor?

Where should it be located?

You need to understand the impact of the sun on temperatures to answer these questions.

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Chart of roof position by temperature to be added here!!!

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The impact of the sun and different coverings on soil temperatures.

Culiacan,

March 25, 2010

Air Temp: 36C

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Direct Sun: 60C Insect Net: 57C

70% black shade: 49C 40% white roof: 49C

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Fruit temperature under insect net: 55C

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A black plate temperature sensor takes into consideration the heating effect of the direct sunlight as well as the air temperature and the cooling effect of the wind. The black plate temperature represents a more true temperature that the plants are exposed to when the roof was retracted.

The best sensor to determine when to close or retract the roof is an exposed

black temperature sensor.

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Notice how the outside surface temperature reached almost 50C (122F) when air temperatures were only around 28C (82F). The heat from the infra red radiation is warming up the sensor to better predict the temperature the plants would feel if the roof is retracted.

March 9, 2009, Culiacan

The difference between an exposed black surface and the air temperature

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With a retractable roof greenhouse, the roofs are closed to protect crops when outside conditions are:• too cold ( below 15C)• too hot (above 30C)• too wet• too windy

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Retracting the roof and walls when outside black plate temperatures are greater than 17C(62F) increases:• Light 50%- 66%• C02 availability• Transpiration• Water stress

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Notice the change in the soil temperature outside and inside the retractable roof.

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Notice the change in humidity from closing and retracting the roof which allows growers to optimize the transpiration rate.

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Optimizing the transpiration rate:• supports a higher level of photosynthesis

• increases nutrient absorption and distribution

• optimizes water stress to influence vegetative or reproductive growth

• builds a bigger buffer in irrigation practices

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Increasing transpiration helps reduce losses due to nutritional deficiencies in nutrients like calcium, magnesium and manganese.

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Transplants grown in retractable roof greenhouses experience higher transpiration rates which helps the plants develop thicker leaves, and more roots which reduces transplant shock.

The low transpiration rates in conventional greenhouses causes young plants to have small root to shoot ratios which increases transplant shock, reduces insect and disease resistance and delays the first harvest.

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Plant density can be increased due to the higher light levels and humidity control.

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Close the roof when spraying to increase effectiveness

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Modify planting schedules to maximize production when prices are best

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2 to 5 year paybacks are possible using retractable roof greenhouses in warm climates

to sell more #1 quality fruits...

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And to ship less to secondary markets!

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Questions????

Richard VollebregtCravo Equipment Ltdrichardv@cravo.com