Greenhouses allow farmers to control the growing environment for plants. They protect plants from extreme weather conditions like cold, heat, wind and precipitation. Different greenhouse structures and covering materials have been developed over time. Greenhouses allow year-round planting and higher crop yields. They control temperature, moisture, light exposure and other factors to optimize plant growth. Greenhouse technology continues to advance with new materials, automated controls and specialized structures.

1. Green House
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3. What is Greenhouse Technology?
 Today about 92% of plants, raised by man, are grown in the open field. Since the beginning of
agriculture, farmers have had to cope with the growing conditions given to them by Mother Nature.
 In some of the temperate regions where the climatic conditions are extremely adverse and no crops can
be grown, man has developed technological methods of growing some high value crops by providing
protection from the excessive cold and excessive heat. This is called Greenhouse Technology.
 “Greenhouse Technology is the science of providing favourable environment conditions to the
plants”.
 It also protects the plants from the adverse climatic conditions such as wind, cold, precipitation,
excessive radiation, extreme temperature, insects and diseases. An ideal micro climate can be created
around the plants.
 Greenhouses are framed or inflated structures covered with transparent or translucent material large
enough to grow crops under partial or full controlled environmental conditions to get optimum growth
and productivity.

6. HISTORICAL BACKGROUND OF
GREENHOUSES
 Before the 20th century - Agriculture production inside protected structures was
initiated in France and Netherlands in the 19th century. This method was applied in
simple, low, glass structures, which provided climate protection, and were used mainly
for the growth of ornamental plants.
 Modern Times - By the beginning of the 20th century, mostly after the end of 2nd world
war, the technology of greenhouse construction accelerated its development, especially in
Western Europe cold countries, Netherlands leading the course. Agro-technical systems,
aeration solutions and accompanying accessories were gradually added to the structures,
while the structure foundations improved to the known, traditional heavy steel
constructions covered by rigid glass boards.

7.  New Materials - By the end of the fifties of the 20th century the greenhouses technology flowed to the
north and center of Europe, extending its influence and benefits to Israel, where a wave of experiments and
research in the field had begun. The sixties revealed a new kind of structure covering sheets. They were the
flexible, low priced polyethylene sheets, which caused a conceptual revolution in the field of greenhouses.
Simultaneously appeared other types of good light transition coverings, such as polycarbonate (a kind of
covering made of plastic polymers) leaving behind the traditional glass covering.
 New Technologies - The method of modular structures (Lego-like method) leads to the development of
growth technologies suitable for most types of crops, thus creating customized structure projects, customer-
tailored according to specific needs. This new trend caused the breakdown of the traditional, conservative
Dutch hegemony ruling until then in the field of greenhouses. Nowadays, light-weighted structures with
covering made of flexible polyethylene or stiff-flexible polycarbonate are more common and widespread
than the mythological rigid glass greenhouses.

8. Plant needs
 Temperature :- 18-30℃
Moisture:- 50-70%
 Co2 :- 300-800ppm(Parts per Milion)
 Sun light:- 400-700 nn(nano meter)
Micro organisms.

10. Advantages of Greenhouses :
 1. Throughout the year four to five crops can be grown in a green house due to availability of
required plant environmental conditions.
 2. The productivity of the crop is increased considerably.
 3. Superior quality produce can be obtained as they are grown under suitably controlled
environment.
 4. Gadgets for efficient use of various inputs like water, fertilizers, seeds and plant protection
chemicals can be well maintained in a green house.
 5. Effective control of pests and diseases is possible as the growing area is enclosed.
 6. Percentage of germination of seeds is high in greenhouses.
 7. The acclimatization of plantlets of tissue culture technique can be carried out in a green house.

11.  8. Agricultural and horticultural crop production schedules can be planned to take
advantage of the market needs.
 9. Different types of growing medium like peat mass, vermiculate, rice hulls and compost
that are used in intensive agriculture can be effectively utilized in the greenhouse.
 10. Export quality produce of international standards can be produced in a green house.
 11. When the crops are not grown, drying and related operations of the harvested produce
can be taken up utilizing the entrapped heat.
 12. Greenhouses are suitable for automation of irrigation, application of other inputs and
environmental controls by using computers and artificial intelligence techniques.
 13. Self-employment for educated youth on farm can be increased.

12. Disadvantages :-
1. CONSTRICTION COST IS HIGH
2) TECHNICAL STAFF NEEDED
3) SUTABLE FOR COMMERCIAL CROPS
4) MAINTENANCE COST IS HIGH

13. TYPES OF
GREENHOUSES
 Greenhouse structures of various types are used for crop production. Although there are
advantages in each type for a particular application, in general there is no single type of
greenhouse, which can be constituted as the best.
 Different types of greenhouses are designed to meet the specific needs.
 The different types of greenhouses based on shape, utility, material and construction are
briefly given below:

14. Greenhouse Type Based On Shape:
 For the purpose of classification, the uniqueness of cross section of the greenhouses can be
considered as a factor. The commonly followed types of greenhouses based on shape are:
1. Lean to type greenhouse.
2. Even span type greenhouse.
3. Uneven span type greenhouse.
4. Ridge and furrow type.
5. Saw tooth type.
6. Quonset greenhouse.
7. Interlocking ridges and furrow type Quonset greenhouse.
8. Ground to ground greenhouse.

16. Greenhouse Type Based on Utility
Classification can be made depending on the functions or
utilities. Of the different utilities, artificial cooling and heating
are more expensive and elaborate. Hence based on this, they are
classified in to two types.
1. Greenhouses for active heating.
2. Greenhouses for active cooling.

19. Greenhouse Type Based on Construction
 The type of construction predominantly is influenced by structural material, though the
covering material also influences the type. Higher the span, stronger should be the
material and more structural members are used to make sturdy tissues. For smaller spans,
simple designs like hoops can be followed. So based on construction, greenhouses can be
classified as
1. Wooden framed structure.
2. Pipe framed structure.
3. Truss framed structure.

21. Greenhouse Type Based on Covering Material
 Covering materials are the major and important component of the greenhouse structure.
Covering materials have direct influence on the greenhouse effect inside the structure and
they alter the air temperature inside the house. The types of frames and method of fixing
also varies with the covering material. Based on the type of covering materials, the
greenhouses are classified as glass, plastic film and rigid panel greenhouses.
1. Glass greenhouses
2. Plastic film greenhouses
3. Rigid panel greenhouses

26. Greenhouse Type Based on Cost of Construction
Based on the cost of construction involved :
1. High cost Green House
2. Medium cost Green House
3. Low cost Green House

27. Low cost
 Naturally control
atmosphere

28. Medium Cost
 FAN, EVAPORATIVE
COLOLING control
atmosphere

29. High Cost
 Air conditioning, Computer
Control atmosphere

30. Construction Material
 In greenhouses, the choice of structural materials is linked to:
 (i) their availability and cost;
 (ii) their technical characteristics depending on the greenhouse to be built (use of wood, steel);
 (iii) the performance required by the greenhouse depending on the crops to be grown;
 (iv) the local climate; and
 (v) the local conditions in terms of experience and creativity.
 The materials commonly used to build frames for greenhouse are Wood, Bamboo, Steel,
Galvanized iron pipe, Aluminum and Reinforced concrete (RCC). The selection of above
materials is based on their specific physical properties, requirements of design strength, life
expectancy and cost of construction materials.

32. In securing the cover: galvanized wire
or profiles galvanized steel or aluminum,
depending on the type of greenhouses.
Canals: galvanized steel or aluminum.
Crop wire: galvanized steel or
aluminum and galvanized wire.

33. Covers are usually made of the
following materials:
Plastic Films: polyethylene
copolímeto ethylene vinyl acetate and
polyvinyl chloride plastics and
multilayer
Rigid plastics: of methyl
polymethacrylate, polycarbonate and
polyester.
Glass: glass patterned glass.

34. Green House Atmosphere Conditions
 The northern parts of our country experience cold winters, where heating system need to be
employed in the greenhouses along with cooling systems for summer.
 Whereas the southern region greenhouses need only cooling systems since the winter cold effect is
not that severe. Greenhouse heating is required in cold weather conditions, if the entrapped heat is
not sufficient during the nights. The heat is always lost from the greenhouse when the
surroundings are relatively cooler. Heat must be supplied to a greenhouse at the same rate with
which it is lost in order to maintain a desired temperature: Heat losses can occur in three different
modes of heat transfer, namely conduction, convection, and radiation.
 Maintenance of desired higher temperature, compared with the surroundings needs heating
systems and heat distribution systems. For the purpose of greenhouse heating, apart from
conventional systems, solar energy can also be used and the heat can be stored using water and
rock storage. Different heat conservation practices are available to effectively utilize the heat
energy.
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35. Plant needs
 Temperature :- 18-30℃
Moisture:- 50-70%
 Co2 :- 300-800ppm(Parts per Milion)
 Sun light:- 400-700 nn(nano meter)
Micro organisms.

36. Green house Atmosphere Control
1. Human control
2. Thermostat
3. Active Summer Cooling System
4. Active Winter Cooling System

38. 5. CO2 Enrichment Method
6. Ventilation
7. Step Controller dedicated Microprocessor Computer
8. Heating

40. HEATING OF GREENHOUSE
A Greenhouse is developed with a motto of getting optimum crop production
or maximum profit. This includes an environment for work efficiency as well
as for crop growth. There are many methods and equipment which are used
for controlling or maintaining desired temperature and other environmental
conditions inside a greenhouse. While selecting a heating system one needs
to consider types of plants produced, level of quality of production strived
for, types of greenhouses used and management procedures followed.

41. Cooling, Shedding and Ventilation Systems of
Greenhouse
Environmental control for heating and cooling uniformity is a very important
design consideration to maintain desired environmental set point conditions
inside a greenhouse.
However, the distribution of heat or cooling is difficult, and a uniformly
controlled environment may not result. Non uniform environments cause
differential plant growth rates, potential disease problems, unpredictable
results with nutrition or hormonal application, and generally a more difficult
plant production system to manage.

42.  For the most effective and uniform cooling and heating, the rows of plants should be
arranged in the direction parallel with the ridge or gutters of the greenhouse structure.
 For ventilation, this assumes that the ventilation system (fans and air inlets) would be
located on the end walls (perpendicular to the direction of the gutters). If airflow is
restricted and non-uniform, then the ventilation system cannot effectively cool the plant,
nor provide the sufficient air exchange for humidity reduction (disease control) and
replenishing carbon dioxide.
 Evaporative cooling systems, whether fan and pad, or high-pressure fog, are highly
dependent upon effective and uniform ventilation, as well.