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Saturday, June 26, 2010


Me and Idrus from Sabah visit Greenhouse Structures at Cameroon Highland recently.

What is Greenhouse?

The simple definition said that “A greenhouse is a structure with a glass or plastic roof and frequently glass or plastic walls it heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building”. Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall. These structures range in size from small sheds to very large buildings. There was a significant different between a greenhouse function between the temperate region and tropical region.

The temperate greenhouse main objective is to maintain the temperature inside the structure during cold or hot season and produce any selected crops. The structure also provided by heat control equipment to ensure the suitable temperature for the crops. The tropical greenhouse mainly built for protection of crops inside the structure from heavy rain and direct sunlight effect. Heavy rain especially monsoon season able to damage leafy vegetables and certain food crops. The structure mostly covered with 32 mesh netting to inhibit any pests to enter inside structure. The trend of greenhouse technology is more accepted my many farmers in Malaysia.

Greenhouses can be divided into glass greenhouses and plastic greenhouses. Plastics Greenhouse mostly used are Polyethylene Film and multiwall sheet in PC or PMMA. Commercial glass greenhouses are often high tech production facilities for vegetables or flowers with glass. The glass greenhouses are filled with equipment like screening installations, heating, cooling, and lighting and may be automatically controlled by a computer. It is more expensive then plastic greenhouse and last longer and effective.

The glass used for a greenhouse works as a selective transmission medium for different spectral frequencies, and its effect is to trap energy within the greenhouse, which heats both the plants and the ground inside it. This warms the air near the ground and this air is prevented from rising and flowing away. This can be demonstrated by opening a small window near the roof of a greenhouse. The temperature drops considerably. This principle is the basis of the autovent automatic cooling system. Greenhouses thus work by trapping electromagnetic radiation and preventing convection. A miniature greenhouse is known as a cold frame.

Greenhouses are often used for growing flowers, vegetables, fruits and food crop plants. Bumblebees are the pollinators of choice for most greenhouse pollination, although other types of bees have been used, as well as artificial pollination. This helps the plants to produce more offspring for future plantations. Many vegetables and flowers are grown in greenhouses in late winter and early spring, and then transplanted outside as the weather warms. Started plants are usually available for gardeners in farmers' markets at transplanting time.

The closed environment of a greenhouse has its own unique requirements, compared with outdoor production. Pests and diseases, and extremes of heat and humidity, have to be controlled, and irrigation is necessary to provide water. Significant inputs of heat and light may be required, particularly with winter production of warm-weather vegetables. Special greenhouse varieties of certain crops, like tomatoes, are generally used for commercial production.

Greenhouses are increasingly important in the food supply of high latitude countries. One of the largest greenhouse complexes in the world is in Almeria, Spain where Greenhouses cover almost 50,000 acres (200 km2) and where almost 5% of Spain's salad vegetables are grown. Cameroon Highland in Pahang using plastic shed and many types of green house for many years. The design, post, structures material keeps changes every year to adapt the greenhouse technology. For lowland design it has to suit the heat so the height of the roof designed higher.
Greenhouses protect crops from too much heat or cold, shield plants from dust storms and blizzards, and help to keep out pests. Light and temperature control allows greenhouses to turn inarable land into arable land. Greenhouses can feed starving nations where crops can't survive in the harsh deserts and Arctic wastes. Hydroponics can be used in greenhouses as well to make the most use of the interior space.

I managed to involve in TKPM Project which provide Greenhouse Structures to commercial farmers. The greenhouse was designed by expert in DOA using plastic roof and galvanized iron with various shape of the roof. There is “Dome shape roof”, “Flat Roof”, “Standard roof” and many other roof design to suit the locality and capital. The height of the post about 10 feet with 30 meter x 8 meter size giving about 500 point to 1,800 points of crop depending on planting system used. There is a pump house and pumping system where the fertilizer mixing activity prepared and sent to the crops. From my estimates the cost of one unit Struktur Pelindung Hujan (SPH) in Malaysia ranging from RM 16,000 – RM 20,000 per unit. I estimate and calculate for one farmer to earn nett income about RM 3,000 per month, he has to manage about 8 unit SPH (Standard size) to grow selected vegetables or fruits. He has to hire 2-3 assistant to manage his farms.

The most popular crops in the greenhouse system in Malaysia were Cherry Tomato, Capsicum, Japanese Cucumber, Melon, Brinjal, Tomato, selected leafy vegetables and watermelon. The roof structure maintainance for at least for five years for the plastic and longer if using glass for roofing. The green algae on the roof have to be clean in 1.5 – 2 years time to encourage sunlight penetration. Greenhouse will be the new trend in future agriculture farming in Malaysia. The greenhouse technology in Malaysia has to be improved and lowered the investment cost to encourage more farmers to adapt the technology!


Related articles :
1. Drip Irrigation (Click here)

2. Rainshelter Technology in Malaysia (Click Technology)
3. NFT Technology for SALAD (Click here)
4. Status of Malaysian Agriculture (Click here)
5. Popular Durian Clones in Malaysia (Click here)

Anem ,

Air Keroh, Melaka,

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