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.

GENERAL CULTURAL PRACTICES: CROP SCHEDULING

Plan ahead… When do you want to market your product for the best monetary return? For hydroponic tomato growers in seasonal countries, get a better price in Winter – no field competition and little from greenhouses in northern latitudes. Alternative: grow year around to maintain stable, consistent market/shelf space. Tomatoes: 2 examples of crop scheduling

• Example 1: Passively cooled greenhouses (vents): No Summer harvesting. Seed first crop in early July in 1" (or 1.5") Rockwool cubes. Transplant in mid-July into 3" (or 4" with 2 holes) Rockwool blocks. Plant 1-month-old seedlings onto Rockwool slabs in August. Harvest from October until March – Top the plants in February, remove when second crop begins producing in March. Seed a second crop in early December as above. Transplant in mid-December as above. Interplant new 1 month old seedlings onto Rockwool slabs in January. Harvest from this new crop from March until July. Remove plants. Clean.
• Example 2: Actively cooled greenhouses (fan and pad): Year around harvesting. Seed, transplant and plant first and second crops as above, removing first crop as above in March. Continue second crop, harvesting from March until the next October. Seed, transplant and plant the third crop, as the first, in July/August. When third crop is ready to harvest in October, remove second crop. Continue the process for up to 5 years.

Note: Concentrate on the production end (growing the plants, harvesting, marketing, etc.)
and purchase 1 month old seedlings from a TRANSPLANT GROWER.
NOTE: Why 2 crops/year? Fruit size and quality go down over time.

Amalan Penanaman Umum - Pemilihan Tanaman Dan Kepelbagaian Jenis Tanaman

Amalan penanaman umum merujuk kepada informasi, teknik & kemahiran yang diperlukan untuk memberikan kejayaan kepada penanaman & mengoptimakan hasil keuntungan - matlamat utama kepada semua para petani

Post kali ini akan menumpukan kepada tanaman Tomato jika dibandingkan dengan tanaman lain untuk menggambarkan kepelbagaian di dalam amalan pernanaman di antara jenis tanaman:

1) Tanaman Dan Pemilihan Kepelbagaian Tanaman - Ini adalah keputusan yang paling penting untuk setiap pengusaha dan ianya bergantung kepada 3 perkara iaitu Pasaran, Lokasi & Pengalaman

• Pasaran: 1) Kajian Persekitaran - Ketahui jika ada petani/pengusaha lain di kawasan tersebut - persaingan. Jika telah ada ramai pengusaha Tomato, cubalah Timun atan Lada benggala. 2) Ketahui pasaran, lokasi peraih, kedai runcit, kedai serbaguna, pasar-pasar peladang, restoran dan lain-lain. 3) Hidroponik/Fertigasi atau penanaman rumah hijau adalah mahal. Oleh itu, tanaman yang memberikan nilai margin keuntungan yang tinggi perlulah dipilih. Ini termasuklah tanaman Tomato, Lada benggala, Timun, Sayur Selada, Melon Wangi dan pelbagai jenis tanaman herba bernilai tinggi serta tanaman yang mempunyai nilai perubatan
• Lokasi: Dari segi ketinggian dari aras laut dan kesesuaian tanaman, suhu, angin, kadar kecerahan cahaya matahari untuk fotosintesis, topografi kawasan, cuaca, habitat serangga (perosak/pemangsa) dan sebagainya. Sila rujuk kepada post 12 Perkara yang Perlu Diambilkira Sebelum Memilih Kawasan/Lokasi Rumah Lindungan (Greenhouse)
• Pengalaman: Jika pengusaha mempunyai pengalaman pada sesuatu tanaman tertentu,..tetaplah pada tanaman tersebut. Jika tidak, dapatkan nasihat dari sesiapa sahaja yang berpengalaman dan sudah berjaya atau dapatkan khidmat pakar.

GENERAL CULTURAL PRACTICES (Crop & Cultivar Selection) – LOCATION

LOCATION: The selection of a crop will dictate the best location for the operation…
and visa versa.
Example: If a grower chooses tomatoes in Cameron Highlands, Malaysia, the optimum elevation is between 3,000 and 4,000 feet. Any lower and it is usually too hot to grow. Any higher and it is too cold to grow (especially during rainy days)…UNLESS SIGNIFICANT EXPENSE ($$) IS PUT TOWARD COOLING OR HEATING!
Example: If a grower has land at about 2500 feet in elevation in Cameron Highland, a crop
that can tolerate warmer temperatures than tomatoes, such as cucumbers could be selected. The selection of a “cultivar” or “variety” is also important when choosing a location. Seed companies are always coming out with new cultivars (or varieties) to suit different climates and tastes. With the move of many growing operations to higher light regions of the world
… remember photosynthesis… (Most of Asian & Middle East countries, Northern Africa, Northern Australia, Southwest USA, Mexico, Spain) AND the demand for good quality, good tasting tomatoes year around, many seed companies are introducing more HEAT TOLERANT varieties. Example (from one of the greenhouse cultivator company in Southwest USA) TRUST Tomato veriety were selected: a Dutch variety (DeRuiter Seed); optimum day temperature = 72 F. The first 10 acres (and next 30) of greenhouses were passively cooled (no fan and pad/evaporative cooling). They were not able to grow in the Summer and therefore started with transplants (1 month old seedlings started in Canada) in August and removed the crop the following July.

GENERAL CULTURAL PRACTICES: CROP AND CULTIVAR SELECTION – Experience

EXPERIENCE: If a grower has experience with a particular crop… stick with it. Example: A family with experience in growing long cucumbers in British Columbia, Canada, moved south of Willcox, AZ and is growing cucumbers… not tomatoes. If a grower does not have experience with a particular crop… Work for someone who is successful with that crop to gain experience.
Hire someone who is experienced… an expert!

GENERAL CULTURAL PRACTICES - (Crop & Cultivar Selection ) – MARKET

INTRODUCTION
General cultural practices include all information, techniques and skills required to successfully produce a crop and optimize yields – the main goal of any grower! We will concentrate on tomatoes with reference to other crops to illustrate the variability in cultural practices between crops.
CROP AND CULTIVAR SELECTION
This is one of the most important decisions a grower will make and depends on:
MARKET… LOCATION… EXPERIENCE

1) MARKET:

• Research the region. Know if there are other growers in the area = competition. If there are too many tomato growers… try cucumbers, peppers, basil, melon, chillies/capsicum etc.
• Know the market. Brokerage houses, grocery vs specialty stores, farmer’s markets, restaurants, etc.
• Hydroponics/greenhouse culture is expensive. Therefore, a high cash-value crop must be chosen. These include: 1)Tomatoes: Indeterminant (vining) varieties to take advantage of the vertical space in the greenhouse that has been paid for! Beefsteak: large fruit, harvested individually. Cluster, truss or TOV (tomato on the vine): medium to large fruit, harvested as an entire truss. Cherry: small fruit, harvested individually or as an entire truss. 2)Peppers/Capsicums: Colored bells only, primarily yellows – require sun protection. 3)Cucumbers: Long (European, seedless, parthenocarpic, burpless). They are thin-skinned and must be wrapped in plastic after harvest. 4)Lettuce: Head, leaf or cos; specialty or bred for hydroponics/CEA (Controlled Environment Agriculture). Summer Bibb or “Limestone” lettuce. 5)Melons: Many types of Melons (Musks, Signal, Cupid, Rock, Sweet etc) 6)Specialty Greens, Herbs and Medicinals: Several types and varieties.
  

NOTE: Consult seed companies for suitable crops/varieties.

2 Perkara Yang Perlu Diambilkira Ketika Memilih Lokasi Rumah Lindungan

Memilih lokasi yang sesuai untuk rumah lindungan adalah sangat mustahak. Tetapi apakah yang dimaksudkan kawasan atau lokasi yang baik? Ada beberapa perkara yang perlu diambilkira ketika memilih lokasi kawasan untuk mendirikan rumah lindungan hujan bagi projek tanaman secara Fertigasi, Aeroponik atau kaedah penanaman hidroponik yang lain:

1. Radiasi Solar (sinar Matahari) - Kadar kecerahan sinaran Matahari yang cukup sepanjang tahun adalah sangat mustahak untuk pertumbuhan tanaman kerana ia menentukan kadar fotosintesis pokok.
2. Bekalan Air - Air diperlukan untuk sistem irigasi/pengairan tanaman. Lokasi yang dipilih perlulah mudah mendapat bekalan air yang bersih dan sesuai dari segi pH & TDS
3. Ketinggian - Ketinggian lokasi dari paras laut juga menentukan jenis tanaman yang paling sesuai ditanam. Contohnya, tanaman Strawberry tidak sesuai ditanam di tanah rendah di Asia Tenggara tetapi hanya sesuai di tanah tinggi.
4. Microclimate - Ia berkaitan faktor-faktor berikut --> * Latitude - aras laut *Persekitaran yang berhampiran kawasan air yang luas (laut, tasik dll) akan mengurangkan suhu terutamanya di waktu malam *Pokok-pokok, bukit bukau & halangan lain *Awan dan kabus *Kawasan angin lintang yang tinggi - ia boleh menyedut haba *Habuk/pasir yang berterbangan * Salji
5. Habitat atau kehadiran populasi serangga - Pemerhatian bukan sahaja terhadap kehadiran serangga perosak, tetapi juga serangga pemangsa yang bermanafaat untuk tanaman untuk kawalan biologi
   
6. Keadaan Potografi kawasan - Tapak lokasi haruslah rata dan tidak melandai terutamanya jika hendak menggunakan setup pengairan automatik.
7. Kemudahan asas - Bekalan elektrik, telefon, dan perparitan
8. Kemudahan jalanraya - Untuk transportasi bahan-bahan pertanian, binaan & hasil tanaman
9. Orientasi Utara-Selatan - Kedudukan orientasi sudut kompas ini adalah penting dari segi *untuk mengelakkan struktur binaan rumah lindungan itu sendiri menjadi bayang-bayang dan menghalang sinaran matahari kepada tanaman *Baris-baris tanaman akan menerima kadar cahaya yang sama untuk mendapatkan hasil yang sekata (uniform)
10. Keupayaan untuk pembesaran - kawasan tapak mestilah cukup besar untuk menampung kemungkinan melakukan pembesaran dengan membina lebih banyak rumah lindungan
11. Kemudahan bekalan buruh/pekerja
12. Pengurusan penempatan - Penempatan/rumah untuk pengurus ladang atau pekerja haruslah berdekatan dengan kawasan yang hendak dipilih
    

12 Thing To Consider When Selecting Greenhouse Site - Expansion, Labour & Management Residence

10. Capability of Expansion – Purchase more land than you anticipate using in the beginning so that you have the ability to expand your operation. Locate the initial greenhouses such that future expansion will utilize the land area most efficiently.

11. Availability of Labor – The grower needs people who will want to work as laborers and who are “trainable” to become a retainable workforce.
*Such skills included pruning/training the plants and harvesting/packing the fruit.
*SPECIALTY LABOR will include people with additional training in such fields as plant production, plant nutrition, plant protection (insects and diseases) computers, labor management, marketing, etc. These may or may not be part of the regular workers, but could be call on as consultants as needed.

12. Management residence – The grower/manager residences should be close to the
greenhouse so that they can get to the greenhouse quickly in case of emergencies.

12 Things To Consider When Selecting Greenhouse Site - Utilities, Roads & North-South Orientation

7. Utilities – Availability of utilities should include telephone service, three-phase electricity and fuel for heating and carbon dioxide generation.*Note that, when compared to propane, electricity or fuel oil, natural gas is the most economical heating energy source.

8. Roads – Need access to good roads to transport the “product”. Good roads close to a large population center, or to a brokerage center aids wholesale and retail marketing.

9. North-South Orientation – The greenhouse should be oriented north-south, AND the
plant rows within the greenhouse should be oriented north-south. *If oriented north-south, the greenhouse structure itself will not cast consistent shadows on any one area of the plants throughout the day. *If oriented north-south, the plant rows will receive equal light throughout the day. If oriented east-west the south most rows (in the northern hemisphere) will shade the rows to the north.

12 Things To Consider When Selecting Greenhouse Site - Pest Pressure & Level and Stable Ground

5. Pest Pressure – Choose a site away from existing agriculture production areas which could harbor insect pests in the fields. Insect pests of concern include white flies, aphids, spider mites and thrips (see here for pests and control methods).

6. Level and Stable Ground – The ground upon which the greenhouse will sit must be

• Graded for routing surface water to a drainage system or a holding pond. (Typical grade = ½ % or a 6 inch drop over a distance of 100 feet.)
• Compacted such that there will be no settling of the site after the greenhouse has been constructed.

12 Thing To Consider When Selecting Greenhouse Site - Elevation & Microclimate

3. Elevation – will effect the summer maximum and the winter minimum temperatures.
Choosing an appropriate elevation will minimize heating costs in the winter and cooling costs in the summer. Example: In Arizona tomato production is most economical between 4000 and
5000 feet (1220m-1520m). Below 4000 feet cooling costs in summer will be more whereas above 5000 feet heating costs in the winter will be more. Lower elevations might be suitable for peppers or cucumbers.

4. Microclimate - Factors which falls in microclimate considerations:

• Latitude – Unless the global climate changes drastically, sea level at the poles will be colder than sea level in the tropics… latitude makes a difference!
• Large bodies of water – will tend to moderate the temperature (e.g., coastal areas tend to have smaller day/night temperature differences than inland areas)
• Trees, mountains or other obstructions – may cast shadows on the greenhouse, especially in the morning or afternoon hours. Mountains can also effect wind and/or storm patterns.
• Clouds and fog – Note that certain areas (e.g., on the lee side of certain mountain ranges, or near coastal regions) may develop clouds or fog during certain times of the day or year that will reduce potential sunlight.
• High Wind Areas – High winds can “suck” heat away from the greenhouse structure and therefore increase the heating energy demands.
• Blowing dust/sand – High winds can “kick up dust or sand”, especially in desert regions, which can damage some greenhouse glazings.
• Snow – The weight of heavy, wet snow on a greenhouse could crush it. However, high winds in snow areas can also blow snow up against the greenhouse structure (snow drifts) and cause damage to it. This danger can be reduced by using windbreaks (trees, snow fences, etc.).

Things To Consider When Selecting A Greenhouse Site - Solar Radiation & Water Supply

Selecting a “good” site for the location of a greenhouse is crucial. But what constitutes a “good” site? There are several things that should and must be considered in order to increase the
chances of a successful operation and business.
12 THINGS TO CONSIDER WHEN SELECTING A GREENHOUSE SITE:
1) Solar Radiation – Plants require sunlight in order to perform photosynthesis. When plants experience cloudy days their photosynthetic rates, and therefore their ability to grow and yield a product, such as tomatoes, cucumbers, peppers, etc., will be reduced. Therefore, a region and location with high light intensity year-round is desired.

2) Water – Water quantity and quality is crucial. Water will be needed for irrigation (maximum of 1 gal/plant/day for tomatoes). Water will be needed for the evaporative cooling system and can equal or exceed the irrigation water amounts (10,000 – 15,000 gal/acre/day). In the past, excess irrigation and bleed-off water from the evaporative cooling system was allowed to “run off” onto the ground adjacent to the greenhouse (with a rec. minimum percolation rate into the soil of 1”/hr.).
*HOWEVER, due to more strict regulations and a desire to avoid ground water contamination with high concentrations of salts, large greenhouses are now recirculating the nutrient solution.
*THEREFORE, excess nutrient solution should be recycled and/or mixed with the cooler bleed-off water and redirected onto designated areas, such as grass, shrubs, trees/windbreaks, etc.
*No matter what the source of the water, a water analysis should be done.
*Note: Sea water = 32,000 ppm (mg/l) VS Tucson water = 200-400 ppm.
Note: 640 ppm TDS (total dissolved solids) = 1 mmhos/cm or 1 mS/cm.

*Desired salt levels in the source water:
SO4 <>

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.

Model Set-up Asas Sistem Fertigasi Terbuka Di Malaysia

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.

Hydroponic/Fertigation Different Type Of Media & Its Characteristics

Media,One of the most obvious decisions a hydroponicist has to make is which medium they should use. Different media are appropriate for different growing techniques:

1. Diahydro - Natural sedimentary rock medium. Diahydro consists of the fossilized shells of algae (diatoms) that lived millions of years ago. Diahydro is extremely high in Silica (87-94%), an essential component for the growth of plants and strengthening of cell walls.
2. Expanded Clay - Also known as 'hydroton' or 'leca' (light expanded clay aggregate), trademarked names, these small, round baked spheres of clay are inert and are suitable for hydroponic systems in which all the nutrients are carefully controlled in the water. Clay pebbles are best not reused as even when they are cleaned. This does not remove roots that actually grow into clay beads. Breaking open a clay pebble after a crop has been grown in it will reveal this. Baked clay pebbles are porous,and can be irregularly shaped or uniform depending on brand and manufacturing process.
3. Rockwool - Rockwool is probably the most widely used medium in Hydroponics. Made from basalt rock it is heat-treated at high temperatures then spun back together like candy floss. It comes in lots of different forms including cubes, blocks, slabs and granulated or flock. When this medium is dry, care needs to be taken so as not to inhale any particles — inhaling such particles may carry a health risk. Rockwool will cause a higher pH level. You must adjust the pH level of the nutrient solution to counteract this. A pH level of 5.5-6.5 should suffice to create a suitable pH.
4. Coir or Coco-peat - from coconut husk fiber, can be used as a compressed medium. Coir comes also in bags and in slabs. Some types of coir are very high in sodium (salt) due to the nature of coconut palms growing on island environments and being processed in the salt air.
5. Perlite - Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in potting soil mixes to decrease soil density. Perlite has similar properties and uses to vermiculite but generally holds more air and less water. If not contained, it can float if flood and drain feeding is used.
6. Vermiculite - Like perlite, vermiculite is another mineral that has been superheated until it has expanded into light pebbles. Vermiculite holds more water than perlite and has a natural "wicking" property that can draw water and nutrients in a passive hydroponic system. If too much water and not enough air surrounds the plants roots, it's possible to gradually lower the medium's water-retention capability by mixing in increasing quantities of perlite.
7. Sand - Sand is cheap and easily available. However, it is heavy, it does not always drain well, and it must be sterilized between use.
8. Gravel - The same type that's used in aquariums, though any small gravel can be used, provided it's washed first. It's inexpensive, easy to keep clean, drains well and won't become waterlogged. However, it's also heavy, and if your system doesn't provide continuous water, the roots may dry out.
9. Brick Shards - Broken up brick has been used in the place of gravel, works just like it, the disadvantage being that it may alter the pH and if recycled, has to be cleaned first.
10. Polystyrene Packing Peanuts - Very lightweight. Cheap, readily available and they drain well. They can be too light, and are mainly used in closed tube systems. Only polystyrene peanuts can be used: the biodegradable ones, of course, will become a sludge.

*Also refer to post Basic Needs For Fertigation 6 - Media Substrates

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

Bagaimana Hendak Memulakan Model Fertigasi Cili?

Post kali ini ditujukan khas buat kawan baik saya, Hafiz (dan adik-adiknya) dari Bandar Baru Uda, Johor Bahru yang sekarang ini sedang 'kemaruk' nak mengusahakan tanaman cili secara fertigasi di kampungnya tetapi bercadang hendak memulakan dengan sebuah model kecil dulu (dalam saiz rumah lindungan 6' X 8' dengan menggunakan atap arcylic atau polycarbornat). Mungkin yang dia maksudkan seperti gambar di atas tetapi saiz yang dia cadangkan terlalu kecil. Dengan saiz 6'X8' hanya boleh menempatkan 8 pokok sahaja, itupun akan menjadi sukar untuk lalu lalang terutama jika enclosed dengan netting. Net yang hendak dipasang mestilah dari jenis greenhouse Vege Net dgn lubang bersaiz 32 mesh dan berwarna putih seperti ini ------->

Saiz 32 mesh adalah saiz rongga yang paling kecil untuk jaring kalis serangga.

Ini adalah mustahak kerana serangga yang harus dielakkan bagi pengusaha cili adalah bersaiz kecil terutamanya whitefly (lalat putih) yang saiznya 3 kali lebih kecil dari nyamuk dewasa. Kos untuk vege net berjejaring 30' (8X6X8X6) adalah dalam RM100+ sahaja.
Tetapi di sini, saya nak mencadangkan pada Hafiz, tak perlu bina model yang terlalu kukuh dan guna kos yang tinggi (terutama untuk atap arcylic yang mana 3 keping dah mencecah RM120). Saya ingin mencadangkan agar membina model rumah lindungan yang dipanggil 'lean-to greenhouse' (seperti pada gambar) yang mana struktur rangkanya dibina bersambung dengan dinding rumah (dengan syarat ia mendapat sinaran matahari terutama pada waktu fotosintesis iaitu dari pukul 9.30 ke 11am). Struktur rangkanya boleh dibuat dari paip PVC yang disambung-sambung menyerupai struktur rumah (oh ya, sebelum itu, masukkan pasir atau rangka besi ke dalamnya dan padatkan-supaya ia tahan lama & tidak melengkung kerana faktor suhu & cuaca). Kos penggunaan net/jaring kalis serangga juga adalah kurang dari struktur yang berdiri sendiri (single built). Plastik greenhouse film boleh digunakan sebagai penutup atap menggantikan kepingan arcylic yang mahal. Guna bahan PVC sebagai struktur rangka jauh lebih murah dari menggunakan kayu dan dengan itu, kos keseluruhan dapat dijimatkan. PVC bersaiz tebal dan berdiameter 15" hanyalah berharga RM0.70/kaki atau mungkin lebih murah. Joint/penyambung 'L' & 'T' hanyalah dalam 60sen ke 70sen seunit. Gambar2 berikut saya sediakan sebagai contoh rujukan model rumah lindungan yang boleh difikirkan. Amacam Hafiz, ok tak? Struktur2 rangka PVC

Seperkara lagi, saya tidak bersetuju dengan cadangannya untuk membuat siraman manual kerana sangat tidak praktikal serta membazirkan baja. Mungkin dia bernggapan bahawa dengan melakukan siraman manual dapat menjimatkan kos lagi. pada hakikatnya tidak begitu. Saya cadangkan agar dia menggunakan set up pengairan titis asas fertigasi yang secara totalnya sangat murah (untuk set kecil sebagai model). Mari kita estimate nilai keseluruhan kos untuk set pengairan automatik 8 point pokok cili tersebut:

1. Timer digital (lihat gambar) : RM32


2. Set Penitis/microtube/nipple : RM12 (RM1.50/set)


3. Pam akuarium (20w) submisable : RM25


4. 16" lateral tubing/hose : sekitar RM5


5. 1 tong bekas baja :RM8 (tong sampah hitam yang saya beli di hypermarket)
   

Jumlah = RM 82 sahaja yang sangat praktikal daripada kaedah manual (walaupun tidak perlu membayar upah). Bayangkan-bagaimana nak appoint orang untuk membuat siraman manual 5 ke 6 kali sehari bermula seawal 6.30 pagi setiap hari selama lebih dari 3 bulan? Mmm.. jenuh, jenuh. Silap-silap, ter..miss siram, pokok pula boleh layu. Banyak baja akan terbazir berbanding pengairan titis yang lebih efisyen. Seperkara lagi, jika terlalu kerap kita keluar masuk ke dalam rumah lindungan yang bertutup sepenuhnya juga tidak digalakkan. Ini adalah kerana kita mungkin akan membawa masuk serangga kecil yang melekat pada badan kita. Oleh itu, siraman secara automatik adalah alternatif yang paling efektif untuk sistem fertigasi.

Untuk jumlah yang sangat sedikit, sebagai model, saya cadangkan menggunakan kaedah semaian anak benih cili menggunakan kapas atau kertas tisu lembut sahaja seperti gambar di sebelah.
Apabila telah mula keluar dua daun primer, bolehlah dipindahkan ke bekas berisi media (jika tiada dulang semaian, boleh juga guna bekas telur-langsung tak melibatkan kos)

Tempoh semaian hingga anak benih sedia untuk dipindah ke 'ladang' ialah di antara 25-30 hari. Apabila sudah mula menghasilkan dalam 6 daun dan pangkal batangnya menunjukkan warna perang-coklat, bolehlah dipindahkan ke point/polybeg yang siap diisi media aggrerat seperti arang sekam & coco-peat.

Benih yang digunakan sebaiknya menggunakan benih terpilih dari jenis Precision Seed atau Hybrid seperti contoh benih di bawah. Veriety yang biasa digunakan di Malaysia ialah DRH 911, Kulai, Long Chili, Hot Chili, Kulai Susu dll. Boleh juga menyemai cili padi dan gunakan sistem pembajaan yang sama dengan cili biasa keperluan baja & kadar pertumbuhan untuk semua jenis 'keluarga' cili adalah sama (tak silap saya, Capsicum atau lada benggala pun boleh).

Kepekatan larutan baja ialah sekitar 1.5 - 1.6mS/cm untuk minggu 1 - 3 dengan jumlah larutan baja/siraman 1 - 1.5L, 1.6 - 1.8mS/cm untuk minggu 4 - 7 dengan jumlah baja 1.5 - 2.0L. Pada minggu ke 8 pula, kepekatannya adalah 1.8 - 3.0 mS/cm dengan jumlah 1.5 - 2.5L. Jumlah larutan baja bagi tanaman cili berubah mengikut umur, peringkat pertumbuhan, cahaya, suhu, kelembapan dan juga jenis media yang digunakan. Siraman hanyalah pada waktu siang sahaja dan bermula pada awal pagi ( siraman selalunya dibuat sebanyak 5 - 6 kali/hari iaitu bermula 6.30am, 8.30am, 10.30am, 12.30am, 3pm dengan sela masa antara 5 - 10 min bergantung pada jumlah keperluan siraman baja yang diperlukan).

Pada peringkat awal lagi haruslah mengawasi kehadiran kutu daun, teritip, lalat putih atau benah yang merosakkan pokok dan memindahkan penyakit bawaan Virus yang sukar dikawal. Satu petua yang saya dapati dari Dr. Mahmud Shahid dari Mardi, Serdang ialah dengan menyembur bahan campuran air & jus bawang putih kepada pokok terutama sekali setelah dipindahkan ke polybeg dan seterusnya setiap 4 hari berikutnya. Untuk lebih mudah lagi, belilah supliment garlic oil di dalam bentuk softgel/kapsul dari mana-mana farmasi. Larutkan 1 kapsul/softgel tersebut dengan 1L air dan semburkan secara merata peda tanaman terutama di bawah daun. Ini merupakan kawalan organik yang ampuh untuk mengelakkan pokok dari deserang serangga yang membawa Virus. Kalau terjumpa kumbang ladybird di mana2, ambil beberapa ekor dan masukkan ke dalam rumah lindungan ini sebagai kawalan biologi kerana ia adalah pemangsa yang terbik untuk mengawal kawasan tanaman dari menjadi habitat teritip, aphid dan lalat putih.

Tempoh memungut hasil pertama adalah pada umur 75 - 80 hari (dari tarikh semaian) dengan warna coklat kemerahan (jangan tunggu ia berwarna merah tua baru nak dipetik). Target hasil sekurang-kurangnya 3.0 kg atau lebih/pokok semusim (2 - 3 bulan pungut hasil)
Salam buat Hafiz, semoga berjaya.

Constructing A Model Greenhouse Video (Fast Forward)

Extreme How To Build Your Own Small Greenhouse Guideline Video

SISTEM KAWALAN DI RUMAH LINDUNGAN - Pencahayaan / GREENHOUSE CONTROL SYSTEMS – LIGHT

PENGENALAN: Apabila struktur rumah lindungan telah dibina, teknik, alat-alatan dan sebagainya mestilah ditambah untuk mengawal faktor persekitaran. Sistem kawalan termasuklah untuk Pencahayaan, Pemanasan, Penyejukan, Kelembapan relatif dan Penambahan unsur Karbon Dioksida.
PENCAHAYAAN: Kepentingan - Memastikan kemasukan cahaya pada kadar & jumlah yang cukup (Radiasi aktif untuk membolehkan Fotosintesis tanaman ialah 400-700nm) melalui struktur rumah lindungan adalah sangat penting bagi menghasilkan fotosintesis yang optimum serta kadar pertumbuhan & hasil yang tinggi.

• Mengenalpasti struktur - Kawasan litupan lapisan penutup yang luas dan tidak dihadang oleh struktur2 lain yang boleh menghalang cahaya seperti alat pemanas, generator, kipas dan sebagainya.
• Terlalu banyak cahaya: Masalah ini lebih tertumpu di negara-negara bermusim yang mengalami musim panas yang melampau dengan kadar cahaya yang terlalu tinggi. Biasanya tanaman yang ditanam di negara-negara ini tidak dapat menampung tahap ini. Ia dapat dikawal dengan menyembur sejenis cat putih khas yang meneduhi ruangan rumah lindungan. Ia akan hilang di penghujung musim panas. Lapisan jaring peneduh juga boleh dihamparkan untuk mengurangkan jumlah cahaya yang terlalu tinggi.
• Terlalu kurang cahaya: Ia berlaku di negara bermusim (terutamanya pada musim dingin) aerta di negara-negara Tropika yang mengalami musim tengkujuh di mana terlalu kerap mengalami hujan serta langit yang terlalu mendung. Ini akan mengurangkan pendedahan cahaya matahari untuk tanaman. Kaedah yang boleh digunapakai untuk mengatasi masalah ini ialah dengan menggunakan pelapik putih di bawah tanaman untuk memantulkan sebanyak cahaya yang mungkin. Cara ini sering digunakan oleh pengusaha berskala besar. Cahaya lampu berpendaflour, lampu wap merkuri atau juga boleh digunakan lampu sodium bertekanan tinggi juga boleh digunakan sebagai pencahayaan tambahan. Namun ia mengakibatkan kos meningkat. Oleh yang demikian, pemilihan kawasan tanaman adalah sangat penting sebelum struktur rumah lindungan dibina

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INTRODUCTION: Once a greenhouse structure is built various techniques, devices, etc. must be added in order to control the environment. Control systems include those for lighting, heating, cooling, relative humidity and carbon dioxide enrichment.
LIGHT: Importance - Maximum light transmission, of the appropriate quantity and quality
(photosynthetically active radiation, 400-700 nm), through the greenhouse structure to the plants is crucial for optimum photosynthesis, growth and yield.

• Structural considerations: Large sections of glazing material (glass, polyethylene, polycarbonate, etc.), held in place by few supports, results in higher light levels and less shading. Minimize other opaque structures above the crop that would cause shading such as heaters, carbon dioxide generators, opaque vents, etc.
• Too much light: Occurs in high light regions such as the desert southwest USA (including Arizona), Mexico, Spain, Middle East etc. during the summer months. Shade paint/white wash: A mixture sprayed on the outside of the greenhouse. This will either wear off by the end of the summer or it can be washed off. External shade cloth: Fabric cloth, placed on the outside of the greenhouse, made of varying degrees of mesh size to exclude specific amounts of light (ex.: 30%, 40%, 50% shade). Internal shade cloth: Fabric cloth, as above, hung inside the greenhouse.
  
• Too little light: Occurs above/below 300 north/south latitudes during the “winter”or for those Tropical countries which having a monsoon season or raining season which limit the sun ray. White reflective ground covers: These are now in common use in commercial greenhouses in all locations and can significantly increase light levels to the plant canopy. Artificial lights: Used above 300 north/south latitudes to extend the winter growing season. Provide day length control (photoperiod) that can initiate plant processes. Provide proper timing of light to control growth (photomorphogenesis). Typical lamp types include incandescent, fluorescent, mercury vapor, high pressure sodium and low pressure sodium. Artificial lighting COSTS MONEY! Therefore, choosing a location that minimizes the use of lights increases profits. Artificial lighting is most cost effective for “transplants” since they require less space.

Bahan Lapisan Bumbung Rumah Lindungan Tanaman

Bahan-bahan tang digunakan sebagai penutup/bumbung struktur rumah lindungan/rumah hijau boleh jadi tetap atau boleh diubah-ubah, 2 lapis atau selapis, licin atau beralun. Kebanyakan bahan pengilat yang dihasilkan sekarang ini menggunapakai bahan yang menghalang kesan buruk dari sinaran UV. Walaubagaimanapun, kesan bahan pengilat ini akan semakin haus dan diukur dari kadar jumlah tahun ia digunakan untuk membenarkan jumlah sinaran cahaya melepasinya. Antara bahan-bahan yang boleh digunakan termasuklah:

1. Kaca - Ia telah lama digunakan (1 abad) di Eropah Utara. 'Rumah Kaca' memerlukan jumlah kayu yang cukup banyak untuk menampung berat kepingan-kepingan kaca. Ia lebih tahan lama (25 tahun) dan menyalurkan cahaya dengan lebih berkesan. Kadar PAR (Penembusan Cahaya) ialah 71% - 92%. Namun ia sangat mahal, berat dan mudah pecah. Kebanyakkan pengusaha sekarang ini lebih memilih bahan Polimer (plastik).



2. Polyethylene: Ia dihasilkan di England pada 1938. Ia lebih fleksibel & ringan serta sering digunakan di rumah hijau yang berbentuk separuh bulat, melengkung dan berbentuk pintu gerbang. Kadar PAR ialah 85% - 87%. Namun begitu, jangka hayatnya hanya 2-4 tahun bergantung kepada lokasi & kualitinya.



3. PVC: Satu lagi lapisan yang mudah diurus dan mempunyai kadar PAR yang sama dengan kaca. Ia sering digunakan di Jepun. Berbanding lapisan Polyethylene yang boleh dibentuk lebar, PVC lebih kecil dan tidak berapa sesuai untuk menutup rumah hijau.



4. Gentian Kaca beralun (Corrugated fiberglass): Ini adalah bahan pelapis yang agak biasa bagi rumah lindungan. Kadar PAR 60 - 88%. Ia murah, kuat dan mudah diurus. Walaubagaimanapun, ia mudah dipengaruhi oleh sinar UV, habuk dan bahan cemar ( harus sering dibersihkan dan dicuci). lama kelamaan, ia akan menjadi kekuningandan mudah terbakar. Jangka hayat 7 - 15 tahun



5. Acrylic: Ia ringan, mudah diurus & tahan pada sinar UV & cuaca. Nilai PAR ialah 83% (2 lapis) dan 93% (1 lapis). Jangka hayat 20 tahun atau lebih. Namun ia mudah tercalar, mudah mengembang dan lama-kelaan menjadi rapuh. Ia murah dan mudah terbakar.



6. Polycarbornat: Ia ringan, murah dan tahan dengan tekanan/hentakan yang kuat. Nilai kadar PAR ialah 79% (2 lapis) & 87% (1 lapis). Penemuan terbaru telah menghasilkan bahan Polycarbornat yang lebih baik (contohnya 'Dynaglass' yang mempunyai nilai PAR yang menyamai atau lebih baik dari kaca). Ketahanan 5 - 10 tahun bergantung pada jenisnya. Ia mudah tercalar, kurang tahan pada perubahan cuaca tetapi tahan dari sinar UV. Namun, baru-baru ini, ia dapat diatasi dengan menyaluti bahagaian bahan ini dengan acrylic.

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The materials used to cover greenhouse structures can be rigid or flexible, double-walled or single-walled, smooth or corrugated. Most “glazing” materials made today incorporate compounds that inhibit rapid degradation by ultraviolet (UV) radiation. However, all glazing material will age and they are therefore rated by the number of years they will maintain a certain level of light transmission capability. (Mica sheets were used in the 1st century A.D. as a glazing on Roman greenhouses. However, this material is no longer used, except perhaps as a demonstration of “ancient technology”.):

1. Glass: This has been in use for at least a century in Northern Europe (Holland, England, etc.). Early glasshouses required significant wood and later metal structures to hold small but relatively heavy panes of glass. This reduced incoming light. Modern glasshouses have large panes of glass with reduced framing of stronger materials to increase light levels. Light transmission (PAR) is between 71 and 92 % depending on the type of glass and the estimated lifetime is 25 years or more. However, glass is inflexible, heavy, easily broken (unless tempered) and expensive and many growers are now opting for plastic materials.



2. Polyethylene: First developed in England in 1938, this flexible, lightweight material is used extensively on hoop or arch style greenhouses because it is easy to work with and inexpensive. A single layer can be used or two layers can be applied with an air layer (maintained by a small fan) in between. This air layer adds insulation from heat and cold and adds structural strength with the double layer polyethylene houses being more stable in areas of high winds or typhoons. Light transmission (PAR) is around 85-87 %. Unfortunately, the estimated lifetime is only 2-4 years, depending on location and quality of the polyethylene.



3. Polyvinyl chloride (PVC): Another flexible film that has light transmission qualities similar to glass. This material has been used extensively in Japan. While polyethylene sheets can be wide, PVC is narrow which is a disadvantage in covering greenhouses.



4. Corrugated Fiberglass (also known as fiber reinforced polyester): This is a common greenhouse glazing. It is inexpensive, strong and easy to work with. Light transmission (PAR) is between 60 (double walled) and 88 %. However, it is susceptible to UV light, dust and pollution (hose down or wash periodically), yellows with age and is extremely flammable. The estimated lifetime is 7-15 years, depending on type of fiberglass . .



5. Acrylic: This glazing material is lightweight, easy to work with and resistant to UV radiation and weather. Light transmission (PAR) is 83 % for double wall and 93 % for single wall. The estimated lifetime is 20 years or more. However, it is easily scratched, has a high expansion and contraction rate, becomes brittle with age, is expensive, and is flammable.



6. Polycarbonate: This glazing material is lightweight, easy to work with and is resistant to high impacts. Typical light transmission (PAR) is 79 % for double wall and 87 % for single wall. However, recent advances have produced polycarbonates (e.g., “Dynaglas”, a single walled, corrugated material) with light transmission properties equal to or even exceeding glass. The estimated lifetime is 5-10 years, or more, depending on type.Previously, polycarbonate was known to scratch easily and have poor weatherability and UV resistance. However, recent advances in material properties have alleviated some of these earlier problems by coating the outer layer with acrylic.

GREENHOUSE STRUCTURES - GREENHOUSE FRAMING MATERIALS

1. Wood: Due to increasing cost and availability of more suitable materials, wood is no longer generally used in large commercial greenhouse construction. If used for smaller greenhouses or in areas where other types of framing materials are not available, wood must be treated for protection against decay, especially the sections that come in contact with the soil. Treatments must be non-toxic to plants and animals (Ex: do not use creosote or pentachlorophenol). Chromated copper arsenate (CCA), ammonical copper arsenate (ACA) or other preservatives containing combinations of copper, chromium and/or arsenic are safe to use around plants. Also treat woods with “natural decay properties” such as redwood or cypress, especially in desert or tropical regions.

2. Reinforced concrete: Usually used for the greenhouse foundation and low walls.
3. Reinforced concrete and bamboo: In the People’s Republic of China, the concrete has been used as support posts for a frame of bamboo.
4. PVC (polyvinyl chloride): Hollow tubes of this plastic material (typical inside diameter of ½ inch) can be used for small scale hoop or arch style greenhouses. These are not necessarily considered “permanent” structures
5. Electrical conduit: This can also be used, like PVC pipe, for small scale hoop or arch style greenhouses. These are not necessarily considered “permanent” structures.
6. Air or air tubes: The structures of some greenhouses of the hoop or arch style (covered with flexible polyethylene film) can be maintained solely by air pressure either by inflating the entire greenhouse or by inflating air tubes that act as structural members. This requires air handling equipment, and if the power fails the greenhouse will collapse.
7. Steel (galvanized): Almost all steel used in greenhouses today is single or double dip galvanized to protect against corrosion. It may be used in conjunction with aluminum. It is usually protected from direct contact with the ground (and subsequent corrosion) by being encased in concrete

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8. Aluminium: It may be used alone or in conjunction with galvanized steel. It is much lighter than steel but is only about one half the strength of an equally sized steel member. It is usually protected from direct contact with the ground (and subsequent corrosion) by being encased in concrete.

Rear wall window installation on the greenhouse video

Contoh Struktur Rumah Lindungan Hujan Rangka Besi G.I di Malaysia

TYPES OF GREENHOUSE DESIGN STRUCTURES

Typical structures include:

• Hoop House or Quonset: A semi-circle design usually covered with a single layer of polyethylene film or with a double layer of film separated by an air layer maintained by asmall fan for insulation. Used for low crops: potted plants, lettuce, etc


• The Arch: A semi-circle design elevated by side walls. Can grow higher crops: taller potted plants, vining tomatoes, cucumbers, peppers, etc.


• Gothic Arch: A variation on the Arch with more rounded side walls.
  


• Ridge and Furrow or Gutter-Connected: Several gable (or arch style) greenhouses connected together usually with no internal separations between the bays. Used for high crops such as vining tomatoes, peppers and cucumbers
  


• The Gable: A structure with side walls and a peaked roof. Optimum for high crops including vining tomatoes, cucumbers, peppers, etc.Several gable (or arch style) greenhouses connected together usually with no internal separations between the bays. Used for high crops such as vining tomatoes, peppers and cucumbers.


• Sawtooth Design: A variation of the gutter-connected style with tall vents on the vertical sections of the roof to allow for natural ventilation. Used for high crops such as vining tomatoes, peppers and cucumbers.


• Geodesic Design : This shape is another type of alternative greenhouse shape. But its not suitable for the large scale, commercial grower.