India is blessed with a diverse agro-climatic environment which helps to grow wide kinds of horticultural crops almost throughout the year in one part of the country or the other. But the quality of produce under open field conditions particularly in case of high-value flowers and vegetables are not suitable for marketing in international as well as for standard domestic markets.? There is a change in occurrence of a number of natural environmental factors for consistent crop production from open agriculture. The need of the hour is to increase the productivity and quality of produce to meet the demand of quality conscious consumers.? A breakthrough in production technology that integrates market-driven quality parameters with the production system, besides ensuring a vertical growth for productivity is required. One such technology is “Protected cultivation” or generally called as greenhouse technology. It is the technique of providing favorable environmental or growth conditions to the crop.? It is the way to achieve maximum yield and best quality by protecting the plants from the adverse climatic conditions, which is by providing optimum conditions of light, temperature, humidity, carbon dioxide, etc, for the best growth and development. A greenhouse is an enclosed structure that protects plants from wind, precipitation, excess solar radiations, temperature extremes and considerable pest and disease attack. Greenhouses have existed for more than one and a half centuries in various parts of the world; they have not become popular in India as our emphasis so far had been on achieving self-sufficiency in food grain production.? There has been a demand for protected technology in recent years in view of the globalization of international market and tremendous boost that is being given for export of agricultural produce.? The location specific trials of greenhouse technology for adaptation in various parts of the country have been recommended by the National Committee for the use of Plastics in Agriculture. Cultivation of crops under greenhouse in the world at present is practiced in more than fifty countries. ? During Roman times, an idea of growing plants in environmentally controlled areas has existed, where Emperor Tiberius was recommended to eat Cucumber daily which was cultivated in artificial conditions. Cucumbers were planted in wheeled carts which were put in the sun daily, and then taken inside to keep them warm at night.? The concept of greenhouse was first used during the 13th century in Italy (exotic plants), 15th century in Korea (mandarin orange) and 17th century in Netherland and England. Today, we will observe several of the biggest greenhouses within the European nation (Netherlands). ? First practical modern greenhouse for growing medicinal plants was built during 1800 by Charles Lucien Bonaparte, a French scientist at Leiden, Holland. ? During Victorian era, largest greenhouses were constructed and this era is considered as the golden era of the greenhouse in England i.e., Kew garden. ? A British merchant, Samuel cocking built the first greenhouse in Japan for herbs during 1880. ? Greenhouses were first introduced in India during 1960’s for research purpose and off-season protection of planting materials. During early 1990’s China and India started protected cultivation, but today China is the world leader in vegetable production by adopting protected cultivation on an area of 2.5 million ha of which ninety per cent area is under vegetable cultivation. ? The availability of smaller land holdings and short growing seasons in the Netherlands and Japan has been the reasons for adopting greenhouse technology. ? Water conservation has been one of the reasons for greenhouse crop production in Israel and Middle-East countries. ? In recent times, the designs are being modified as per the requirements, crops and varieties are also being identified which can be raised well under protected conditions. ? But, even after concerted efforts, the coverage of the area in India under protected cultivation has only increased to 30,000 ha. In the country at present vegetable is being cultivated on an area of nine million ha.? A proper approach is required to convert maximum area under protected cultivation of vegetables and flowers in order to increase the national productivity.  The main principle for selection of crop to be cultivated in a greenhouse depends on the structure and economics of crop production. With this context, high-value horticultural crops, particularly cut flowers, and some vegetables are suitable for protected cultivation.? Some of the important crops grown in greenhouse are Rose, Chrysanthemum, Carnation, Gerbera, Anthurium, Orchid and ornamental plants; off-season vegetables like Tomato, Capsicum, Cucumber, Cabbage and Lettuce in India.? Recently farmers are also adapting low-cost greenhouse technology for production of high-quality fruits in hilly states like Jammu and Kashmir, Himachal Pradesh, Uttaranchal and North East states, where crops like Strawberry, Grapes, Cherry, Apricot, and Plum were growing.? In china, the protected cultivation for nectarine and peach is around eighty and twenty per cent respectively.? In addition, a raising of seedlings (mainly vegetables and flowers), production of plant material and hardening of tissue culture plants are some of the other important commercial applications of greenhouse technology.To increase productivity there are mainly two approaches i.e., first by improvement in the genetic base and second one by providing favorable environment conditions. In a given genetic material, the yield potential is fully exploited only when a favorable growing environment is available. Environment refers to light, temperature, air composition and nature of root medium. Traditionally it is possible to control only nature of root medium by way of tillage, nutrition, irrigation, etc. Under greenhouse conditions, productivity and quality of produce increases since near to optimum growing conditions will be maintained as per the requirement of the crops. Besides, productivity will also be enhanced due to the following reasons.  The diffused light coming inside the greenhouse through transparent cladding materials, plants tend to grow upwards and utilize the vertical space inside the structure. Because of this number of plants per unit area (plant density) could be increased to get more productivity.  By covering the ventilators during night time, there will be an increase in the concentration of CO2 inside the greenhouse due to respiration of plants inside. This increased concentration of CO2 will be utilized efficiently for the photosynthesis in the morning hours and will help to increase dry matter content in plants and ultimately yield will be increased.   The crops under greenhouses are grown under optimum growing conditions. This helps to maintain good health of the plants and extend the duration of the crop and ultimately productivity will be enhanced.  The photorespiration is regarded as a wasteful process as it normally reduces twenty five per cent yields in plants. Under fully controlled greenhouses, and there will be facilities for an enrichment of CO2 concentration inside. The increased concentration of CO2 will reduce the rate of photorespiration and ultimately yield will be increased. Salient Featuresa. Commercial cultivation of flowers, vegetables, and fruits under cover  High-value flowers like Orchid and Anthurium were grown under partial environment controlled greenhouses.  Bird of Paradise and Heliconia were cultivated under shade houses.   Naturally ventilated polyhouses were used for raising Gerbera, Carnation, and Rose crops.  Vegetables like colour Capsicum, Tomato, Cucumber and exotic vegetables under both polyhouse and shade house.  Fruits like Strawberry, Grapes, Cherry, Apricot, Peach and Plums are grown under low-cost polyhouses.b. Adoption of Micro- irrigation, Fertigation and Mulching technology   Plasticulture application in agriculture and horticulture has brought significant changes.  Especially, savings in water and fertilizer, besides, obtaining a higher yield of superior quality produce.  Computerized micro- irrigation and fertigation are adopted for protected structures to obtain quality and quantity output.  Plastic mulching for some crops and also drip irrigation for outdoor cultivation of high-value fruits, flowers and vegetables is adopted.  c. Mass multiplication of plant materials under cover   Genuine and healthy plant material supply to the farmers is a great service to the farming community. Hence, Hi-Tech ground nursery and facility for mass multiplication of fruits and flower plants are established with the assistance of National Horticulture Mission (NHM) at different districts.  Planting material produced will be supplied to the farmers.   Hi-Tech production of vegetable seedlings under cover is also part of the plant material production. d. Greenhouse Roof-Top Water Harvesting  Water from greenhouse roof-top is harvested and collected in irrigation/fertigation tank at Hi-Tech Horticulture unit during rainy days and utilized for irrigation of greenhouse crops.  Otherwise, water has to be collect from the source to the irrigation tank.  Water collected is sufficient for all the protected structures and also for some outdoor crops.   This technology saves water and more importantly the electricity which is a scarce commodity.Chapter-2Greenhouse Planning, Design and ConstructionTraditional agriculture seeks to essentially control only the nature of the growth medium by way of tillage, manure and fertilizer application, irrigation, etc., and there is no control on light, temperature and air composition under open field conditions.• In this context, structures for protected cultivation have a remarkable role, where greenhouses are frames or inflated structures covered with a transparent material in which crops may be grown under the conditions of at least partially controlled environment and which are large enough to allow working and carry out cultural operations. • There are innumerable studies quantifying the effect of the environmental parameters individually as well as collectively on crop growth and yield. Selection of the siteSelection of the location should be near to market, well connected with roads to market for input supplies and sale of produce. o Adequate communication means – telephone, fax, internet, etc should be available. The site should not be located in the vicinity of an industry on its down side because of possible pollution effects on greenhouse crops.o The location should be fairly shadow free and at the same time, the area should have sufficient wind breaks on all sides to minimize the wind damage to the proposed structures.o The site should be well drained with a land slope of two-three per cent.o There should be sufficient space for future expansion. o In areas where snow is expected, wind break trees should be at least thirty meters away from the greenhouse for checking the snow drifts. o Availability of laborers is around six-seven per acre throughout the year.Factors deciding the area under greenhouse• Interest of the farmer• Economic condition of person• Availability of water and electricity• Crop type• Market – Domestic and Overseas• Availability of skilled labour• Sufficient area for future expansionThe orientation of the GreenhouseThere is a lot of information which is confusing. There are two main criteria relevant to greenhouse orientation.a) The light levels in the greenhouse should be adequate and uniform for crop growth.b) The prevailing wind should not adversely affect either the structure or the operation of the facility.On the basis of these two criteria, researchers from different parts of the world have made recommendations which appear contradictory.There are two types of orientations1. East-West orientation: Gutter should be in East-West direction, where the availability of sunlight is more during the winter season.  ? The advantage is keeping on increasing as we go away from the equator and reduces winter heating costs and this type of orientation is applicable for single span structures.? However, in multi-span structures shade of gutter falls on crops of particular place affecting adversely the crop growth. This type is generally suitable for temperate regions like Holland, Jammu and Kashmir, Netherlands and so on. ? The only disadvantage is the pre-monsoon winds may affect the structure.2. North-South orientation: Gutter should be in the North-South direction. Generally, it is recommended for tropical countries like Israel, India, etc.  ? In multi-span structures shadow of gutter moves during the day and therefore, the crop growth in a specific area is not affected. Moreover, agricultural scientists have recommended the same orientation for crops grown under open cultivation.? While considering the orientation, wind direction should be taken into account. ? In the naturally ventilated greenhouse, the ventilators should open on the leeward side and opposite to wind direction.The layout of GreenhouseThe various facilities required are store house, cold storage, packing and grading hall, office, pump house, security cabins, residential quarters, etc. A general layout i.e., the master plan should be prepared based on the following factors. 1. Buildings should be located to the north of greenhouse to avoid shading. 2. Separate roads to be there for the cold storage and store. 3. Entry of people or customer to greenhouse should be restricted.4. The wind breaks should be at least thirty meters height on the north and west from the greenhouse.5. There should be sufficient space for expansion. Utilities The requirements of water and electricity are the important utilities. Water ? An adequate supply of good quality water is necessary.? The water requirement depends on the area under production, crop type, and climate.? A general rule is to make a provision for about 1.0 lakh L/ha/day. Quality of water is important for good production. General recommendations are as below   pH of the media should be around 7  EC±1 ds/m2,    Salts like Fe, Mg, Mn, carbonates, bicarbonates, and chlorides should be less.  Electrical supply should be uninterrupted for irrigation motors, fans, pre-cooling and cold storage, spraying, etc.  There should be a provision of suitable capacity generator.Types of GreenhousesThere are many types of greenhouses developed for different applications.I. Based on the types accepted by Governmenta. GH-I (Naturally ventilated): Partially controlled, open ventilator type, cooling is affected through ventilation i.e., a difference of temperature gradient inside and outside.  b. GH-2 (Fan and pad): Completely controlled, no ventilators, the temperature is controlled with exhaust fans and cooling pad. For better performance, the suitable technical design should be done. c. GH-3 (Completely control1ed): Completely automatic with sensors, double inflated poly film. To keep two layers of poly films away from each other, blower and motor should be provided. There should be the provision of CO2 apparatus, computer, exhaust fans and cooling pads.II. Based on the glazing material a. Glass – Before the Second World War, most of the greenhouses were constructed using glass as the glazing (cladding/covering) material. b. Plastic film – i. Poly ethylene (PE), ii. Poly vinyl chloride (PVC), iii. Poly vinyl acetate (PVA), iv. Acrylic, polycarbonates, v. Fibre reinforced polyethylene (FRP), vi. Polyester, and vii. Poly vinyl fluoride (PVF) III. Based on the shapeA number of greenhouses on the basis of shape are available.a. Hoop styleb. Trussed roofc. Gable framed. Circulare. Quonsetf. Tri-pentah. Dome IV. Based on the Spana. Single span structure: When only one span is used as described in shape, and then they are called as single span structures. – Many single span structures can be erected. It permits convenient expansion / contraction of business. – It permits the production of a different plant material by maintaining different micro-climate in different units. – Flexibility can be seen with this type and gutter is not required. b. Multi spans structureIt is an economy in construction, for cooling and heating operations and cultural operations. There is no flexibility and different crops cannot be grown in one structure. The gutter is required.Constructional material for the greenhouses A greenhouse maintains the favorable climate suitable for growing crops.? This objective needs to be achieved at an affordable cost. ? The greenhouse structure should be light yet it should be strong enough to withstand certain forces/loads.? The greenhouse is considered to be semi-permanent structure and should be designed for service life of twenty-twenty five years.? The greenhouse must resist a load of its own weight, Wind load, Snow load and Crop load.Minimum values of GH designs loads       Load Minimum value (kg/m2) Dead: a. Pipe frame 10b. Bass frame, lapped glass, 25c. Hanging baskets 20Live: a. Snow    75 b. Wind To be estimated based on area ? Maximum recommended a live load of 68 kg/m2 of covered ground area. ? A greenhouse should be designed to resist a wind velocity of 100 km/hr. ? Wind load is affected by the direction of the wind, shape of greenhouse, wind breaks and the opening of the greenhouse.? Snow load depends upon the roof slope, snow fall, single span or multi-span and whether heated or unheated.  Method of constructiona. Foundation? Foundation should be strong enough to support the super structure against various forces. ? Pit or pile foundation is common because columns are widely spaced and the depth should be at least 60 cm reaching too hard strata with a width of 60 cm. ? The foundation may be Reinforced Cement Concrete (RCC), CC or telescopic, whereas the telescopic foundations are easier and cheaper than RCC or CC. b. FloorsGreenhouse crop may be grown in soil or soilless. The floor of the greenhouse should have drainage. For soilless cultivation, sometimes porous concrete floors having the depth of 10 cm are prepared.c. Frame? The common materials of frame construction are steel, wood, bamboo, aluminum and RCC. ? The frame includes columns, bottom cord, truss members, purlins, knee bracing, wind bracing, fitting members, etc. ? Wood should be treated for protection from high moisture and termites and painted for better light conditions in the greenhouse. ? Coal tar is a good preservative for underground portion of wood.? Steel components to be used in greenhouse frames should be hot dipped galvanized to avoid rusting. ? Sometimes to reduce the cost, mild steel is used for the frame. Mild steel should be painted with two coats of red oxide and two coats of oil paint to avoid rusting.? Painting should be carried out at least once in two years. ? Steel or aluminum frames transmit more light as compared to wooden ones. ? The frame members should be smooth to avoid damage to the covering material.d. Glazing material fixing? Commonly used glazing materials are glass, poly film, poly carbonate sheets, acrylic sheets and FRP sheets. ? Except for poly film, all other materials are rigid and comparatively heavy in weight.? However, the material used for fixing/fitting the glazing material remains more or less same. They are fitted with any of the following materials. i. Wooden battens: Generally 2.5-3.5 cm battens of suitable length are used. However, if the length is less, then work of fitting increases. For poly-film, length of batten may be 3 m or more to have convenient working. Battens may be salwood, teak, mango, season or silver oak. Covering materials are fitted in the battens with nut and bolts.  ii. Plastic grippers: The gripper made in ‘U’ shape from plastic is used. They are available in coils of 100, 200, 300 m. This type of gripper has a protruding surface for ensuring grip. Nevertheless, for additional firmness, spring clamps are also used. Over the period, due to properties of plastic gripper may be degraded.iii. Aluminum profiles: Aluminum profiles are shaped in ‘C’. The film is fixed in ‘C’ profile with hammering the PVC pipe. Sometimes the film is also fixed with ‘Z’ shaped continuous GI wire.Glazing Materials for greenhouses The covering of a greenhouse or any structure with the transparent material is known as glazing or cladding. The glazing material includes glass, poly film, poly carbonate, FRP, PVA, acrylic, polyester, PVF. Except for poly film and PVC, all other materials are rigid panels/ sheets.Radiation properties of glazing material When a beam of radiation is incident on a material, a part of it may be reflected back, apart may be absorbed by the material and remaining portion will be transmitted. ? Depending upon the material composition and surface properties, the radiation absorbing ability, reflectivity and transmissivity values are determined.? For a given material, the values of three coefficients must add to 1.0 with reference to a particular radiation beam. ? A transparent material transmits a large portion of light through it, whereas, an opaque material either reflects or absorbs the incident radiation. ? A translucent material may transmit a large portion of radiation but the transmitted light is diffused in nature. ? In case of greenhouses, the transmissivity of radiation property is important. The values of transmissivity for various glazing material are given below (Table 2.1).Table 2.1: Transmittance values for various glazing material              Glazing material Solar transmittance (%)  a. G