AMALAN PENANAMAN UMUM - Melatih Tanaman & Cantasan / GENERAL CULTURAL PRACTICES - Training & Pruning

TRAINING AND PRUNING

In general greenhouse crops (tomatoes, peppers and cucumbers) are indeterminant (vining) types to take advantage of the vertical volume of the greenhouse.
*The plant vines are supported on vine twine by vine clips. The twine is wrapped around some sort of device from which it can be unwound (tomahook, bobbin, etc.). Plants are trained up the twine to the wires forming a “V” shape. As the plants grow up to the overhead support wire, the twine is unwound, the plants lowered and shifted one space – “LEANED AND LOWERED”.

Tomato vines should not be lowered more than 2 feet at a time OR another good way to tell, DO NOT lower the vine such that an 80 or higher degree bend is created in the vine near the floor. High angles promote stem cracking.
*Plants are trained to 1-3 stems by removing (pruning) side shoots or “suckers”. Tomatoes are trained to 1 stem (or 2 stems to replace a topped or broken neighbour or during a season of high light, i.e., Spring or early Summer).
Peppers are usually trained to 2 or 3 stems. Their stems are much more brittle than tomatoes and tend to snap if they are leaned and lowered. Cucumbers have traditionally been trained using such methods as the “V-cordon” or “umbrella”. However, they can also be trained to 1 stem like tomatoes.

*Side shoots or suckers are so named because they suck nutrients from the main plant. The process of removing suckers = “sucker pruning” or “suckering”.

*NEVER PRUNE SIDE SHOOTS WITHIN 2 INCHES OF THE TOP! It is too easy to remove the APICAL MERISTEM, the top growing point. If the apical meristem is removed or damaged (the plant is “topped”), a lower side shoot or even a sucker from a neighboring plant will need to be allowed to grow and take over as the apical meristem. This will take time and this plant will now be behind the others. Therefore, STUDY the top of the plant carefully, DETERMINE the location of the apical meristem, MOVE 2 inches down, THEN begin pruning!
*Extra growths may also occur on fruit clusters. These should be removed.
*Leaves: As the plants grow old leaves furthest from the apical meristem will begin to age or senesce = yellow spots appear due to the loss of chlorophyll. These leaves are no longer contributing as much to photosynthesis. These leaves should be removed – usually 3 leaves once a week. This is about the usual number of leaves that appear at the meristem per week.
The first three leaves will be removed when the plants reach 4-6 feet.
Leaves should be removed in the morning when the plants are “turgid” (full of water) so that they break off crisply. Leaves should be removed at the stem-petiole abscission zone – the bulbous point of attachment of the leaf petiole to the main stem. This abscission zone forms a clean break and seals quickly. If the leaf is “ripped” off, the damaged tissue could provide a point of entry for pathogens.
NOTE: Removing old, lower leaves also allows for air movement around the
lower part of the plant. This reduces humidity that can promote disease.
Also, certain insect pests tend to reproduce on lower leaves. Pruning
reduces their overall populations.

Watch these 2 videos on How To Prune Tomatoes:

Amalan Tanaman Umum - Jarak Pokok & Susun Atur Tanaman / General Cultural Practices - Plant Spacing & Crop Layout

Jarak Tanaman ditentukan oleh 2 faktor berikut:
1) Kehadiran cahaya kepada lindungan - Tanaman mestilah dijarakkan cukup jauh dari sebarang objek untuk mendapat jumlah cahaya yang sampai kepada daunnya semaksima mungkin untuk kadar Fotosintesis yang paling optima.

2) Bekalan air & zat untuk akar - Tanaman mestilah cukup jauh jaraknya untuk mendapatkan bekalan yang cukup untuk kedua - dua bahan ini.

* Jarak tanaman di rumah berpelindung adalah lebih dekat berbanding di atas tanah/batas. Contohnya, Tomato di atas tanah = 4000 - 5000 pokok/ekar
Tomato secara Hidroponik/Fertigasi = 10,000 - 11,000 pokok/ekar
Mengapa? Rumah lindungan berdiameter kecil dan akar tanaman yang ditanam secara hidroponik/fertigasi 'disuap'kan dengan bekalan air/zat yang cukup dan berkala. Oleh itu, tidak perlu mempunyai sistem perakaran yang besar.
Akar tanaman yang ditanam di atas tanah akan berkembang untuk mencari air & zat. Oleh itu pokok yang ditanam di atas tanah mestilah dijarakkan sejauh mungkin untuk mengelakkan persaingan dengan pokok bersebelahan. Oleh itu, pengairan titis/fertigasi membolehkan jarak yang lebih dekat.
*Contoh jarak tanaman Hidroponik:

• Tomato = 2.5 – 3 pokok/meter persegi
  
• Lada Benggala = 2.5 – 4 pokok/meter persegi
• Timun = 1.25 – 3 pokok/meter persegi
• Melon = 2.5 - 3 pokok/meter persegi

Susun atur tanaman di dalam rumah lindungan haruslah pada barisan yang cenderung tepat menghadap ke Utara & Selatan. Ini adalah penting kerana pada waktu siang, Matahari bergerak dari Timur ke Barat dan jika baris tanaman diatur menghadap arah Timur ke Barat, baris yang paling Selatan akan melindungi cahaya kepada baris tanaman di belakangnya.
Seringkali tomato ditanam di baris berkembar yang berjarak 5-6 kaki dengan 3 pokok untuk setiap polibeg 'bantal' (slab) sepanjang 1 meter. yang disusun sebelah menyebelah.


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Plant spacing is determined by two main factors:
1) The availability of light to the canopy - Plants must be far enough apart so that a maximum amount of light reaches the leaves for optimum photosynthesis.
2) The availability of water and nutrients to the roots - Plants must be far enough apart so that all plants have an optimum supply of these items.
*Plant spacing in “vining” greenhouse crops, including tomatoes, is much closer than for field crops.
Example: Field (bush) tomatoes = 4000 – 5000 plants/acre.
Hydroponic greenhouse tomatoes = 10,000 – 11,000 plants/acre.
*Why? A vine has a much smaller diameter than a bush, so they can be closer together and the leaves will still obtain optimum light for photosynthesis. The roots of a plant growing in hydroponics receives all the water and nutrients it requires. They are “spoon-fed” and do not have to grow large systems. The roots of a field grown plant will be more spread out as they search for water and nutrients in the soil matrix. Therefore, field grown plants must be positioned far enough apart to avoid competition of neighboring plants for water or nutrients. NOTE: Drip irrigation allows for closer spacing.
*Typical hydroponic plant spacing:

• Tomatoes = 2.5 – 3 plants per square meter
• Peppers = 2.5 – 4 plants per square meter
• Cucumbers = 1.25 – 3 plants per square meter
• Melon = 2.5 - 3 plants per square meter
  

*The typical layout of the greenhouse for vining vegetable crops is in rows tending approximately north and south. This is important because during the day the sun moves from east to west and if the rows were also set up east to west the southern most rows (in the
northern hemisphere) would shade the rows behind them. Typically, tomatoes are also grown in “double rows”. These double rows are usually 5-6 feet apart. With 3 plants per Rockwool slab (1 meter long each) or perlite bag (about 36”), sets of 2 slabs/bags are placed side by side. With 6 plants per slab/bag a single row of slabs/bags is used. Overhead support wires are set at least 2 feet apart.

AMALAN PENANAMAN UMUM - Keadaan Persekitaran / GENERAL CULTURAL PRACTICES : Enviromental Conditions Required

2) Suhu: Suhu yang optima untuk pertumbuhan tanaman berbeza dari spesis tanaman dan jenis tanaman di dalam spesis yang sama. Contohnya, untuk kebanyakan tanaman jenis tomato, suhu yang paling sesuai untuk pendebungaan dan pembuahan ialah 23-25 C manakala suhu yang paling sesuai untuk penghasilan buah pula ialah 25 C.

3) Kelembapan Relatif (RH): Ia merujuk kepada kandungan air di udara berbanding jumlah air di udara yang boleh 'dipegang' pada suhu tertentu. RH yang terlalu tinggi akan menyebabkan sistem perpeluhan pokok menurun kerana molekul air dalam pokok sukar untuk keluar. Ini akan juga menyebabkan kekurangan zat pada tanaman. Ia juga boleh mengundang penyakit bawaan kulat & hama pada tanaman.

4) Karbon Dioksida: Ianya penting untuk proses Fotosintesis.

5) Kitaran Udara: Ia penting untuk mengelakkan berlakunya udara terperangkap di dalam rumah lindungan yang akan mengakibatkan perubahan suhu (tinggi/rendah) yang sangat ketara dengan udara di sekitarnya.

6) Oksigen: Penting untuk pernafasan. Selalunya tiada masalah untuk bahagian atas pokok mendapat bekalan Oksigen yang mencukupi akan tetapi keadaan media yang terlalu basah/air bertakung dan suhu yang terlalu tinggi akan mengurangkan jumlah oksigen dari akar ke bahagian atas pokok.

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2) TEMPERATURE: The optimum growing temperatures (day and night) vary for different
plant species and different varieties within a species. Eg. for most Tomatoes, germination and post-emergence temperatures = 23-25 C (74-77 F). Production optimum temperatures = 22 C (72 F) day/20C (68 F) night.

3) RELATIVE HUMIDITY (RH): The amount of water in the air compared to the total amount of water that the air can hold at a given temperature. %RH = Amount of water in the air X 100 Amount of water possible at a given temp. As the temperature increases the amount of water that the air can hold increases. When the air is saturated water molecules condense. This causes clouds when at altitude or fog when near the ground. How does this relate to tomato plants growing in a greenhouse? As the RH increases around the leaf (concentration of water molecules outside increases) it makes it more difficult for the water molecules inside the leaf to move out (transpiration) via diffusion (the passive movement of a substance from high to low concentration . Therefore, as the RH increases, transpiration decreases, water and therefore
nutrient movement decrease, and nutrient deficiencies can result. ALSO, as RH increases and transpiration decreases, leaf temperatures often increase, since transpiration is the plant’s way of cooling itself.
Optimum RH range for tomatoes (and most plants) = 55% - 95%. During hot, dry weather, fan and pad cooling adds moisture to the air. On hot, humid days, fan and pad cooling adds moisture but does not cool as well. During cool, damp weather, RH inside the greenhouse can approach 95%.

4) CARBON DIOXIDE: As mentioned earlier, carbon dioxide is critical for photosynthesis and enrichment is most important during the Winter on cold mornings. Outside ambient levels are around 330 ppm, part per million, (higher in cities due to industrial exhaust products). Enrichment = 800 to 1000 ppm.

5) AIR CIRCULATIONS: This avoids pockets of high or low temperature, humidity or carbon dioxide. This also reduces the BOUNDARY LAYER (the physical “still air” layer around
the leaf) so that proper gas exchange and transpiration can occur. When cooling fans are off use HAF (horizontal air flow) fans in the upper part of the greenhouse.

6) OXYGEN: All parts of the plant require oxygen for respiration. There is usually no problem supplying the top part of the plant with enough. But waterlogging and high temps. will inhibit oxygen movement to the roots.

AMALAN PENANAMAN UMUM - Faktor Keadaan Persekitaran / GENERAL CULTURAL PRACTICES - Environment Conditions Required

Faktor-faktor ini merangkumi 1) Cahaya 2) Suhu 3) Kelembapan Relatif (RH) 4) KarbonDioksida 5) Kitaran Udara dan 6) Oksigen
Kita akan mulakan dengan faktor Cahaya dahulu.

1) Cahaya: 2 faktor yang penting dan boleh dipengaruhi oleh struktur rumah berpelindung terhadap tanaman di dalamnya ialah:

• Kualiti: Ia merujuk kepada gelombang cahaya tersebut (sebagaiman yang disebutkan tentang cahaya spektrum di dalam matapelajaran Fizik iaitu faktor PAR ( Aktif radiasi untuk Fotosintesis ) iaitu biru, kuning, oren & merah.
• Kuantiti: Ia dipengaruhi oleh tempoh lamanya waktu siang dan juga sudut matahari (ia ketara di negara-negara bermusim).
  

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These factors includes 1) Light 2) Temperature 3) Relative Humidity (RH) 4) Carbon Dioxide 5) Air Circulation and 6) Oxygen. First we will cover - Light: Two factors are important and can be affected by greenhouse structures and coverings . NOTE: Both of these vary with plant species.

• Quality: Refers to wavelengths of light. (Remember in physics: light spectrum) Visible light = 390-760 nm: blue at the low end, red at the high end. PAR (photosynthetically active radiation) = between 400 and 700 nm (blue, yellow, orange and red… but not green)NOTE: This varies slightly for each plant species.
• Quantity: Is affected by both day length and sun angle (changes with season): Day Length & Sun Angle.
  

The quantity (amount) of light reaching the Earth’s surface is therefore higher in Summer than it is in Winter.
For tomatoes in the desert southwest or other high light areas:

1. During the Winter or times of low light the quantity of light available is enough to support 3 – 4 fruit/cluster.
2. During Spring/Summer/Fall the quantity of light may be too high and shading may be needed. 4 – 5 fruit/cluster is typical.
   

AMALAN PENANAMAN UMUM - Menyediakan Rumah Lindungan / GENERAL CULTURAL PRACTICES - Greenhouse Preparation

Perkara2 yang perlu dipertimbangkan sebelum menyediakan rumah lindungan hujan:

* Pilih kawasan atau lokasi yang bersesuaian dengan operasi (lihat post2 12 perkara yang perlu dipertimbangkan untuk memilih lokasi rumah lindungan)
* Pilih struktur rumah lindungan yang bersesuaian (lihat post2 struktur & bahan komponen rumah lindungan)
* Pastikan kesemua peralatan adalah bersih, diservis dan berfungsi secara optimum.
* Untuk kesemua jenis tanaman, perkara-perkara berikut haruslah dipertimbangkan sebelum menanam:

• Kemasukan cahaya yang cukup - Pilihlah pelapik atap atau dinding (jika perlu) yang sesuai untuk membenarkan cahaya matahari menembusinya secara optimum. Namun begitu, jika merancang untuk penghasilan sepanjang tahun, gunakan jaring penapis sinaran cahaya (sunshade) pada musim panas terik.
• Sistem Penyejukan yang cukup - Samada penyejukan pasif (lubang/ruang udara) atau aktif (kipas) atau kedua-duanya sekali.
• Pembekalan gas Karbon Dioksida - Ini hanya selalu digunapakai di negara2 yang mengalami musim dingin.
• Pelapik/Pengalas tanah - Selalunya menggunakan bahan plastik putih atau berkilat (juga dipanggil Silvershine Weed Suppressor) digunakan. Ia memantulkan cahaya untuk meningkatkan kadar fotosintesis, memberikan perlindungan pada media tanaman dari patogen2 tanah dan mengawal pertumbuhan rumput./lalang.
• Mempermudahkan aktiviti2 pembersihan - Sampah2, daun2 kering dan air yang bertakung adalah habitat yang sesuai untuk serangga perosak & penyakit
• Sistem Pengairan/Irigasi Ini termasuklah 1) Alat pengatur masa (Timer) atau 'controller' untuk menetapkan jadual 'fertigasi'. 2) Bekas/takungan/tangki menyimpan air bersih atau larutan baja 3) Injektor 4) Tiub-tiub penyambung/penitis/pengitar larutan baja 5) Alat-alat penyukat pH, EC atau TDS 6) Dawai2 trelis -yang cukup kuat untuk menampung berat pokok untuk membuat ruang-ruang melintang bagi poko di dalam kawasan rumah lindungan.
  

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Factors To Consider For The Greenhouse Preparation:

*Select a site for the greenhouse that is appropriate for the operation (see posts 12 Things To Consider When Selecting A Greenhouse Site).
*Select a greenhouse structure that is appropriate for the operation (see posts on Greenhouse Structure).
*Make sure all equipment is cleaned, serviced and working at optimum efficiency.
*For any crop, incl. tomatoes, the following items must be considered prior to planting:

• Good light transmission: Choose the proper greenhouse covering and structure. If year-around production is planned, shading must be used in Summer.
• Adequate cooling: Either passive (vents), active (fan and pad), or both. Heating is necessary in Winter: NATURAL GAS is the most economical way. (Other, more expensive, methods of heating: propane, oil, electric, solar.)
• Carbon dioxide generation: This is especially important for Winter mornings. The sun rises, but it’s cold. So if fans come on, it’s only for a short time. Plants begin to photosynthesize, using up the ambient carbon dioxide to the point where photosynthesis is effected and even reduced.. If photosynthesis is reduced, fruit set is reduced – and that’s $$!
• Ground cover: Usually white plastic or a white woven material is put down first. Reflects light back up into the crop increasing photosynthesis. Provides a barrier between the plants and pathogens in the soil. Helps to control weeds.
• Allows for ease of cleaning: CLEANLINESS IS PARAMOUNT! Trash, leaf litter, etc. is a perfect habitat for bugs/disease.

• Irrigation system: (see posts on Irrigation System for details and diagram) This inlcudes: 1)Timer/controller to regulate the “fertigation” (water + fertilizer) schedule. This will be hard-wired to solenoid valves that open for watering. 2) Reservoirs to contain the nutrient solution (full strength or concentrate). 3) Injectors (if concentrates are used) to dilute the nutrient solution. 4) Distribution tubing/emitters/drainage and/or recycling system. 5)Possibly integrated pH (acid/base) and EC (electrical conductivity) probes. 6) Overhead support wires: These need to be strong enough to support the crop and high enough (8-14 feet) to make use of the vertical space provided.

Environment Control System In A Greenhouse

Control systems can be very simple or very complex. Examples include:

1) The "original" environmental control systems were manual:

• Manually rolling up a side vent.
• Manually opening a roof vent or door.
• Manually turning on a heater or cooler.

2) Simple controllers operate from a thermostat in the greenhouse and:

• Automatically set day and night temperature ranges.
• Automatically open and close vents (side, roof, etc.).
• Automatically turn on or off heaters and coolers.

3) Step controllers operate from a thermostat in the greenhouse and:

• Automatically set day and night temperature ranges.
• Automatically control 1 or 2 heating stages (depends on # of heaters).
• Automatically control several cooling stages using cooling fans and
  pump(s) to wet the pads.

4) Sophisticated computers operate from a temperature sensor in the greenhouse and:

• Automatically set day and night temperature ranges.
• Automatically control heating equipment including boilers, root zone
  heating, heat retention curtains, etc.
• Automatically control other equipment including HAF fans, exhaust
  fans, vents, pad pumps, fogger systems, etc.
• Automatically control relative humidity.
• Automatically control shade curtains and artificial lighting depending on
  light requirements.
• Sophisticated computers can also monitor an external weather station and use
  data from that station to control internal conditions in the greenhouse.
• Data monitored includes: outside light, temperature, RH, rain and wind.
  Sophisticated computers can also operate the fertigator system
• Automatically using light quantity (e.g., X ml of solution/Y amt. of light)
• Automatically controlling timing of watering, duration of watering,
  nutrient solution pH and EC, misting, watering booms, etc.
  

Sistem Kawalan Rumah lindungan - Pengudaraan / Greenhouse Control System - Air Circulation

Kepentingan: Salah satu sebab untuk membina rumah lindungan ialah untuk mewujudkan 'persekitaran terkawal' untuk tanaman dan setiap tanaman di dalamnya harus menerima keadaan yang sama. Walaubagaimanapun, apabila tiba keadaan di mana sistem pemanasan atau penyejukan tidak berfungsi, suhu yang tinggi atau rendah akan terperangkap dan kelembapan serta kandungan Karbon Dioksida yang tidak sesuai akan berlaku. ianya akan menyekat pertumbuhan tanaman dan pembungaan/penghasilan buah.

Cara-cara meningkatkan pengudaraan: Konsep HAF (Horizontal Air Flow) atau Aliran Udara Mendatar membantu meningkatkan pengudaraan di dalam rumah lindungan. Ianya boleh mengurangkan penyakit dari kelembapan yang tinggi. Udara yang bergerak mengeluarkan kelembapan dan menyediakn persekiratan yang kering. Ia juga boleh meningkatkan kadar Karbon dioksida yang diperlukan oleh tanaman di siang hari. serta boleh menghalang berlakunya keadaan suhu panas/sejuk yang terperangkap di dalam persekitaran rumah lindungan yang tertutup dengan menyalurkan udara segar di dalam persekitaran kawasan tanaman.

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Importance: One reason for having a greenhouse is to create a "controlled environment" for
all of the plants. And each plant within the greenhouse should receive the same conditions. However, especially during times when the heating and cooling systems are not in operation, pockets of high or low temperature, relative humidity or carbon dioxide may develop which can be less than optimal for plant growth or flower/fruit development.
Ways of improving air circulation:
The Horizontal air flow (HAF) concept utilizes the principle that air that moves in a coherent horizontal pattern in a building like a greenhouse needs only enough energy to overcome turbulence and friction loss to keep it moving. Besides the obvious advantage of more uniform temperature within the greenhouse, HAF systems can reduce the incidence of foliar diseases. The moving air removes moisture from the plant canopy resulting in a drier microclimate. When leaf temperatures are allowed to cool much below the air temperature, the dew point is reached and condensation occurs harboring disease organisms. Radiant cooling on clear nights,, especially in non-infrared poly covered houses will cool plant leaves several degrees below air temperature. HAF will reduce this difference.
During daylight hours, photosynthesis depletes the carbon dioxide that is in the boundary layer of air next to the leaf. Moving air will replace this depleted air with fresh air having a higher carbon dioxide content. If carbon dioxide is being added, a lower level is usually adequate to get the same plant responses, for instance, 800 - 1000 ppm rather than 1200 - 1500 ppm. Horizontal air flow fans can be placed in the rafters of the greenhouse to circulate air above the crop. This helps to minimize pockets of warm or cold air and high or low humidity or carbon dioxide within the greenhouse. HAF fans can be used in conjunction with hot air heating systems to circulate warm air throughout the greenhouse. HAF fans can also be used at anytime to enhance air mixing in the greenhouse.

KAWALAN RUMAH LINDUNGAN - PEMBEKALAN CO2 / GREENHOUSE CONTROL SYSTEMS - CARBON DIOXIDE ENRICHMENT

Importance: The rate of photosynthesis is dependent upon the availability of carbon dioxide.
Carbon dioxide enrichment is most important during the winter months in the morning. The sun has risen and photosynthesis has begun. The plants can reduce the levels of carbon dioxide from the ambient level of about 330 ppm (higher in cities due to industry and vehicles) to around 220 ppm. Lowered carbon dioxide levels will reduce growth and can cause flower and
fruit drop reducing overall yields.
*Ways of controlling carbon dioxide levels in the greenhouse:

1. Ventilating (bringing air in from the outside) may provide sufficient carbon dioxide during the Spring, Summer and Fall months.
2. Ventilating during the Winter months, or anytime in cold climates, will, however, result in cold outside air being brought into the greenhouse. Heating will then be needed to maintain the proper temperature which may become uneconomical. Therefore, carbon dioxide generation is a typical and effective way to increase levels in the greenhouse during the Winter or in cold climates.
   
3. Carbon dioxide generators can burn various types of fuel including natural gas (most economical)or propane. Carbon dioxide levels above 800 ppm, even as high as 1200 ppm, have been shown to be beneficial to plant growth.

SISTEM KAWALAN DI RUMAH LINDUNGAN - Penyejukan / GREENHOUSE CONTROL SYSTEMS – Cooling

Kepentingan: Suhu yang terlalu tinggi boleh menjejaskan pertumbuhan tanaman. Ia boleh mengakibatkan masalah2 berikut:

• Batang yang kurus teutamanya pada pangkal tangkai tanaman tomato
• Mengurangkan saiz bunga terutamanya pada tanaman tomato yang menghasilkan bunga bercantum & pembentukan bengkak
• Melambatkan proses pembungaan dan/atau pendebungaan yang tidak berkesan untuk menghasilkan buah.
• Kemusnahan bunga/putik buah

Keperluan Penyejukan & Pengiraannya - 8 kaki persegi untuk setiap minit/kaki persegi bagi keluasan lantai rumah atau jumlah 1 lot rumah dibanding dengan kepanasan cuaca setiap minit.
CFM = (tinggi X lebar X panjang)
Contoh, Jumlah kawasan bawah + jumlah ruang persegi atap,
(8 X 24 X 48) + (6/2 X 24 X 48) = 9216 + 3456 = 12,672 kaki persegi/min (saiz kipas mengikut ruang kawasan ini).

Pengudaraan Pasif:

1. Teduhan - Jaring peneduh atau cat putih khas mengawal kadar kecerahan sinaran cahaya (light intensity) yang terlalu terik dan mengurangkan kepanasan
2. Ruang Rabung Terbuka - Rabung atap yang terbuka bertujuan untuk melepaskan kepanasan/angin panas dari dalam. Kawasannya mestilah 25% dari ruang lantai.
3. Dinding yang digulung ke dalam - Ia bertujuan untuk melepaskan udara panas dari arah tepi
4. Menara penyejuk - Lapik basah yang dingin di bahagian atas menara menyejukkan udara sekitar
5. Atap boleh buka - Rekabentuk terbaru membolehkan atap dibuka sepenuhnya untuk membolehkan pengudaraan semulajadi

Sistem Penyejukan Aktif:

1. Kipas & pelapik basah - 'Penyejukan Sejatan' di mana udara dari luar disedut melalui lapik basah yang mudah menyerap (selalunya kertas selulosa). Kepanasan dari udara akan menyejatkan air dari pelapik itu dan meningkatkan kelembapan relatif di rumah lindungan.
2. Sistem Semburan Kabus - Menggunakan penyejukan sejat/sedut tetapi menggunapakai titisan air halus yang menyejat dan menyedut kepanasan dari udara. Sistem ini lebih merata kerana kabus air dilepaskan di sekitar rumah dan bukannya dilepaskan berhampiran dengan pelapik basah dengan kipas. Lebih kecil saiz titisan air, lebih cepat ia tersejat dan lebih cepat proses penyejukkan. Ukurlilit titisan kabus air yang efektif = 1000 miro-meter
3. Alat Hawa Dingin - Terlalu mahal untuk rumah lindungan secara komersial
   
   
   

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Importance: High temperatures can be detrimental to plant growth. High temperatures can cause such problems as

• Thin, weak stems or, as in tomatoes, stick trusses (thin, weak truss stems)
• Reduced flower size or, as in tomatoes, flower fusion and boat formation
• Delayed flowering and/or poor pollination/fertilization and fruit set
• Flower and bud/fruit abortion
  

*Cooling requirements and calculations: The National Greenhouse Manufacturer’s Association 1993 standards = 8 cubic feet per minute/square feet of greenhouse floor area OR…
1 full greenhouse volume exchanged per minute in warm climates. CFM = height x width x length (i.e., volume)
Example: Using the greenhouse dimensions in the heat calculation example:
CFM = volume lower section + volume triangular top
= (8 x 24 x 48) + (6/2 x 24 x 48)
= 9216 + 3456
= 12,672 cubic feet per minute => size fans/pads accordingly

*Passive ventilation systems:

1. Shading: Shade cloth or shade paint/white wash, besides regulating the light intensity, can also help cool the greenhouse.
2. Ridge Vents: Vents in the roof of a greenhouse that allow hot, interior air to escape. The area of the vents should be 25% of the floor area.
3. Roll-up Side Walls: Can be used in flexible glazing (polyethelene film) single bay greenhouses where the side walls can be rolled up several feet allowing a natural horizontal flow of air over the plants. As with ridge vents, the area of the side wall vents should be 25% of the floor area.
4. Cooling Towers: Water cooled pads at the top part of tall towers cool the surrounding air which then drops displacing warmer air below.
5. Removable Roof: Recent greenhouse designs can include a roof that retracts completely for natural ventilation. This would allow for adaptation of greenhouse grown plants to outside conditions prior to movement outside.
   

*Active cooling systems:

1. Fan and Pad: “Evaporative cooling” where air from the outside is pulled through porous, wet pads (usually cellulose paper). Heat from the incoming air evaporates water from the pads, thereby cooling the air. Evaporative cooling will also help to increase the relative humidity in the greenhouse.
2. Fogging Systems: Uses evaporative cooling like the fan and pad but incorporates a dispersion of water droplets that evaporate and extract heat from the air. This system gives better uniformity since the fogging is distributed throughout the greenhouse and not just near one a pad end as with the fan and pad system. The smaller the droplet size, the faster each droplet evaporates and therefore the faster the cooling. Mist droplets = 1000 microns in diameter.
3. Air Conditioning: Too expensive for most greenhouses

GREENHOUSE CONTROL SYSTEMS – Heating

• Importance: Each plant species has an optimum temperature range. Heating devices
  will maintain the temperature within that range during periods of cold weather.
  *Types of heat loss from a greenhouse:
• Conduction = Heat transfer either through an object or between objects in contact. Conduction depends on area, path length, temperature differential and physical properties of the object(s). Example: Heat loss through the glazing material on the greenhouse.
• Convection = Heat transfer by the movement of warm gas or liquid to a colder location. Convection depends on temperature differential. Example: Movement of warm air near the plants upward toward the roof.
• Radiation = Heat transfer between separated objects. Radiation occurs from all objects and depends on the areas, temperatures and surface characteristics of the objects involved. Example: Heat transfer from all objects in the greenhouse.
  

It is important to be able to estimate the heat loss from the greenhouse in order to choose the correct size of heater to replace that heat. Although radiation and convection transfer heat around the greenhouse, the main type of heat loss from a greenhouse is through conduction, i.e., the heat loss through the glazing material.
*The basic system: Consists of a fuel burner, heat exchanger, distribution system and controls. Heat delivery to the crop is by convection and radiation. The fuel = usually burn natural gas, but can also use oil, coal, wood, etc.

• Heating by hot water or steam: Hot water or steam can be produced using boilers fired by natural gas, etc. The hot water or steam is then transported throughout the greenhouse in pipes. The pipes can end in a heat exchanger where a fan distributes heated air. The pipes can run along the floor and also be used as cart rails between aisles. Heat will then rise upward through the crop by convection. Heat pipes can also be positioned within the crop to steer plant growth . Heated tubes can create “bottom heat” for propagation or growing.
• Heating by hot air: Fuel is burned to heat air that is then distributed by fans around the greenhouse. Horizontal air flow (HAF) fans circulate warm air above the crop. Fan jet systems, with unit heaters or heat exchangers and perforated polyethylene tubes, distribute warm air and improve air movement and ventilation throughout the greenhouse.
• Moveable nighttime insulation: Insulating material (cloth or film curtains) can be positioned above the crop or near the roof to retain heat near the crop. The insulating material used during the night can be the same material used for shading during the day.

Those are called dual fin heating tubes. The hot water from the boilers enters into these tubes, which radiate the heat out towards the plants