Orientation, design and principles of polyhouse

Orientation, design and principles of polyhouse.pptx

1. ORIENTATION, Principles and design of STRUCTURE for Polyhouse JANAHARSHINI R

2. Introduction A polyhouse is a specially constructed st ructure for growing plants under controlled conditions. The most important function of the greenhouse structure and its covering is the protection of the crop against hostile weather conditions (low and high temperatures, snow, hail, rain and wind), diseases and pests. It is important to develop greenhouses with a maximum intensity of natural light inside. The structural parts that can cast shadows in the greenhouse should be minimized.

3. Why we go for protected cultivation? Higher yield Year round cultivation Better quality Off-season production Assured production Generate self employment for the educated rural youth in the farm sector Least pesticide residues Controlled pollination Vagaries of weather Easier plant protection Weed free cultivation Need of Protected Cultivation

4. ORIENTATION OF POLYHOUSE For maximum availability of Sunlight in greenhouse at latitudes less than 40⁰ in Northern hemisphere the ridge of the greenhouse has to be oriented in North South Direction. This avoids falling of shades on adjacent greenhouses and moving of the gutter shade across the greenhouse. However, the wind direction has also to be considered for proper ventilation. The wind direction perpendicular to ventilator/ridge gives better uniformity of temperature in the greenhouse. The wind parallel to the ventilators gives better stability to structure and safety of the glazing material. ORIENTATION Single Span – Any direction Multispan – North –South Direction Only

5. PRINCIPLES OF POLYHOUSE Under protected structure major fraction of incoming solar radiation is absorbed by plants and earthern objects. These objects inturn emit long wave thermal radiations for which cladding material has low transparency. Thus, long wave thermal radiations are trapped inside the structure, which raises the inside temperature.This is called GREENHOUSE EFFECT. Owing to this rise in temperature inside the structure, growing off season crops in cold climate becomes possible. During summer, temperature inside the structure is brought down by providing cooling device or appropriate ventilation.

6. DESIGN OF STRUCTURE The structure has to carry the following loads and is to be designed accordingly. a) Dead load:   weight of all permanent construction , cladding, heating and cooling equipment, water pipes and all fixed service equipments to the frame. b) Live load:   weights superimposed by use (include hanging baskets, shelves and persons working on roof). The greenhouse has to be designed for a maximum of 15 kg per square meter live load. Each member of roof should be capable of supporting 45 kg of concentrated load when applied at its centre. c) Wind load:  The structure should be able to withstand winds of 110 kilometer per hour and at least 50 kg per square meter of wind pressure. d) Snow load:  These are to be taken as per the average snowfall of the location The greenhouse should be able to take dead load plus live load or dead load plus wind load plus half the live load.

7. COMPONENTS OF POLYHOUSE Roof: transparent cover of a greenhouse. Gable: transparent wall of a green house. Cladding material: transparent material mounted on the walls and roof of a green house. Rigid cladding material: cladding material with such a degree of rigidity that any deformation of the structure may result in damage to it. Ex. Glass Flexible cladding material: cladding material with such a degree of flexibility that any deformation of the structure will not result in damage to it. Ex. Plastic film Gutter: collects and drains rain water and snow which is place at an elevated level between two spans. Column: vertical structure member carrying the green house structure Purlin : a member who connects cladding supporting bars to the columns Ridge: highest horizontal section in top of the roof Girder: horizontal structure member, connecting columns on gutter height Bracings: To support the structure against wind Arches: Member supporting covering materials Foundation pipe: Connection between the structure and ground

8. CLASSIFICATION OF POLYHOUSE

9. Based on shape

10. Lean-to greenhouse A lean-to greenhouse shares a wall with a building and relies on the building structure to provide some support for the greenhouse roof Advantages Useful where space is limited Least expensive, availability of water and electricity Disadvantages Temperature control is difficult Location of windows and doors on the supporting structure must be kept in mind

11. Ridge-and-furrow greenhouse A ridge-and-furrow greenhouse is composed of a number of greenhouses connected along the length of the house. The shared interior walls reduce energy costs and allow for large interior spaces. Ridge-and-furrow greenhouses are best oriented north and south to reduce permanent shadows on the crops created by the gutters.

12. Even-span greenhouse An even-span greenhouse is a single house that has a roof with an even pitch and an even width. A common even-span greenhouse that uses arching pipes for the framework is called a hoop house. Advantages Provides more usable space and can be lengthened Can accommodate two to three benches for growing crops. Better shape for air circulation Disadvantages Most costly option

13. Uneven-span greenhouse An uneven-span greenhouse has unequal pitches and widths. Use of this style is limited to hillsides. Modern greenhouses are built on level ground. Therefore, uneven-span greenhouses are rarely built

14. Quonset greenhouses Quonset greenhouses are also known as hoop houses or polyethylene tunnels, are constructed from pipe either PVC or metal, bent into hoops and draped with polyethylene films.

15. SAW-TOOTHED GREENHOUSE In these structures, the roof consists of a series of vertical surfaces separated by a series of sloping surfaces, all of which are pitched at a same angle and facing in the same direction. These are most efficient for ventilation. These are suitable for multi span structures

16. GOTHIC ARCH GREENHOUSE This style features the walls that are bent over the frame to make a pointed roof.

17. GABLE GREENHOUSE The most basic structure similar to the hut-like construction with glass or rigid transparent plastic panels as the covering material. It has sloping, flat roofs connected to vertical sidewalls

18. GAMBREL GREENHOUSE These structures are similar to gable but have high strength to withstand high windloads during storms . This system is more suitable where wood or bamboo are to be used for greenhouse construction

19. 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.

20. Greenhouse for Active Heating During the night time, air temperature inside greenhouse decreases. The requirements for heating greenhouse depend on the rate at which the heat is lost to the outside environment. Various methods are adopted to reduce the heat losses, viz., using 1. Double layer polyethylene, 2. Thermopane glasses (two layers of factory sealed glass with dead air space) or 3. Heating systems, such as unit heaters, central heat, radiant heat and solar heating system

21. Greenhouse for Active cooling During summer season, it is desirable to reduce the temperatures of greenhouse than the ambient temperatures, for effective crop growth. This type of greenhouse either consists of evaporative cooling pad with fan or fog cooling . This greenhouse is designed in such a way that it permits a roof opening of 40%-100%

22. BASED ON CLADDING MATERIALS Polythenes or other transparent material used for walls and roof of a greenhouse for protection as well as transparency, which simulates climatic conditions inside the greenhouse is called cladding material. 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: 1. Glass, 2. Plastic Film 3. Rigid Panel Greenhouses

23. The following factors are to be considered while selecting the greenhouse covering material Light transmission Weight Resistant to impact and Durability to outdoor weathering Thermal stability over wide range of temperatures.

24. Glass A clean, transparent provides the maximum light transmittance to 90% . It is brittle and breaks with minimum shock or vibrations resulting in high maintainance cost. Glass as covering material has the advantage of greater interior light intensity . These greenhouses have higher air infiltration rate which leads to lower interior humidity and better disease prevention. Lean-to type, even span, ridge and furrow type of designs are used for construction of glass greenhouse

25. Plastic film Flexible plastic films including polyethylene, polyester and polyvinyl chloride are used as covering material in this type of greenhouses. Plastics as covering material for greenhouses have become popular, as they are cheap and the cost of heating is less when compared to glass greenhouses. The main disadvantage with plastic films is its short life For example, the best quality ultraviolet (UV) stabilized film can last for 4 years only. Polycarbonate has a life span of 15-20 years. Polycarbonate is better than glass. Quonset design as well as gutter-connected design is suitable for using this covering material

26. Rigid panel Poly vinyl chloride rigid panels, fibre glass reinforced plastic, acrylic and polycarbonate rigid panels are employed as the covering material. This material is more resistant to breakage and the light intensity is uniform throughout the greenhouse when compared to glass or plastic. High grade panels have long life even up to 20 years . The main disadvantage is that these panels tend to collect dust as well as to harbor algae, which results in darkening of the panels and subsequent reduction in the light transmission

27. Covering material Life span Glass and acrylic sheet 20 years Polycarbonate and fiberglass-reinforced polyester sheet 5-12 years Polyethylene 2-6 months Polyethylene stabilized for UV rays 2-3 year

28. Materials used for frame The greenhouse frame can be constructed from different types of material. The most common material for greenhouse frameworks are Bamboo, wood, mild steel pipes, galvanized pipe and aluminium. Bamboo and wooden frames It is constructed for low cost polyhouse which is easy and affordable for the resource of farmers Pine woods or timbers are used But it has less life (3-5 years) It has to be re-build or carry out major repair (changing rotten components) along with change in polythene sheets. Permanent type of frame It is constructed using metallic material such as GI pipes which are stronger as well as corrosion resistant and has life more than 25 years . It remains protected against any damage by external forces like wind or snow .

29. Aluminium / steel combination frames In northern latitudes it is important that the framework be strong enough to withstand heavy snow loads. Aluminum and aluminum/steel-combination frameworks are popular because they are long lasting and considered low maintenance. However, they are more expensive than other frameworks, such as wood, galvanized steel, and angle iron.

30. Wooden framed structure Pipe framed structure Truss framed structure

31. Low cost polyhouse It is fabricated mainly using local and low-cost available material like wooden logs or bamboos . The protection of wooden structures from insects and termites is a major challenge. These structures are small in size and have a short life-span . Since the height of the structure is lesser as compared to those with steel frames, maintaining proper temperatures in summer becomes difficult. Therefore, they are recommended mostly in cold climatic zones and low wind speed regions. The approximate cost of establishing such greenhouse units ranges between Rs. 450–620 per sq m. BASED ON cost

32. Medium cost polyhouse It is generally fabricated using galvanised iron (GI) square or rectangular or round pipes or lipped channel or their combinations. The whole structure is firmly fixed in the ground to withstand high speed wind up to 140 km/hr. Such greenhouses are suitable for dry and composite climatic zones. The normal height of these structures ranges between 6.5–7 m and these are mostly naturally ventilated. The climate inside the structure is regulated by opening and closing of side curtains (which are rolled above permanently fixed insect-proof net on windows). Thus, air circulation can be regulated. Humidity is maintained through operation of foggers/ misters . Light intensity can be controlled with the use of internal collapsible shading nets. The approximate cost of establishing such naturally ventilated polyhouse unit ranges between Rs. 900–1000 per sq m depending upon the size of the structure

33. High cost polyhouse For the production of sensitive, off-season, exotic or quality crops, sometimes medium-cost greenhouses cannot deliver the requisite quality. Therefore, high-cost greenhouse structures, which can precisely regulate climatic and nutritional needs of the plants, are required. The greenhouse climate parameters are regulated through passive cooling by operating fan and pad systems and sensor-based controlled systems . The approximate cost of establishing such greenhouse units ranges between Rs.1500– 2500 per sq m depending upon the size of the structure

34. Satish kumar , alok kumar , sardar sunil singh , rajkishore prasad and RB verma . Effect of plastic low tunnel on flowering and fruiting behaviour during off season of summer squash. J pharmacogn phytochem 2018;7(4S):72-75. MATERIALS AND METHODS The field experiment was conducted in winter season during 2009-10 & 2010-11 at vegetable research farm of the Bihar Agricultural College, Sabour , Bhagalpur, Bihar. The experiment was conducted in randomized block design in three replications with seven treatments. The treatments comprised the seven dates of sowings i.e., 30th November under open field, 15th December under open field, 30th December under tunnel, 15th January under tunnel, 30th January under tunnel, 15th February under open field and 28th February under open field. Summer Squash – Australian Green For making plastic low tunnel, 60 cm width, 50 cm high and 50 micron transparent plastic were used, immature bamboo stick were pegged on the both sides of water channel. The tunnels were made in north-south direction and vents were made in tunnel on east side. Plastic of the tunnel was removed from the bed in the 2nd week of February in each year. The data were recorded on vine length (cm), primary branches, first female flower appearance, first picking, fruit length (cm), fruit girth (cm) and fruits per plant. Seedlings were raised by sowing seeds in plastic protrays which were filled with growing media prepared by mixing coco peat: vermiculite: perlite in the ratio of 3:1:1 (V/V). Seedlings were ready in about 20-25days. Vine length was measured from the base of each plant to the growing point of a main vine.Primary branches per plant are the total number of fruiting branches emerging from the main stem was counted at the time of last picking. The fruits selected for recording fruit length were used for measuring fruit diameter in centimetres at middle periphery of fruits with the help of Verneer Callipers .

35. TABLES

36. RESULTS AND DISCUSSION – Flower Attributing Parameters Days taken to first female flower appearance and first harvest were significantly influenced by the sowing date and growing conditions. Minimum number of days taken to first female flower and first harvest was observed when the sowing was done on 30th December under low tunnel (T3) over other date of sowing under low tunnel. Early flowering force to early fruiting. Data related to first flowering and first harvest of fruits was due to air temperature inside the tunnels was always recorded higher as compared to outside. The maximum temperature different of about 10 oC between inside and outside. The favourable effect of low tunnel on flowering and harvesting might be due to the conducive microclimate condition through which crop had reached to early flowering and fruiting by increasing the temperature at that time. Ogden and van Iersel (2009)have also indicated that low tunnels modify climatic conditions, promoting earlier flowering and fruit ripening as well as fruit precocity production. Obshato and Shabalina (1984) opined that the time of fruiting was related to early temperature condition which favour to low tunnel structure. In similar study conducted by Ibarra et al. 2001 observed that muskmelon crop grown under plastic cover flowered 24 days earlier than uncovered plants.

37. Maximum fruit length, fruit girth, fruit weight, yield per plant, fruit per plant and yield per hectare were found when the sowing was done on 30th December under low tunnel (T3) over other date of sowing under low tunnel. It might be due to better growth and development of all yield contributing parameters under low tunnel which increases the net photosynthesis and production of more assimilates available for individual to grow. Singh and Kumar (2009) found that out of the five varieties of summer squash evaluated for their off season cultivation under plastic low tunnel during winter period, variety Australian Green took minimum days (58) to fist harvest after transplanting along with maximum fruit yield per plastic (5.90kg/plant) and highest total fruit yield (696.0q/ha),Similar results were also given by Singh el al (1989) . Vegetative growth was greatest in plants in the tunnel where the the thermal condition were best early and total marketable yield were highest under the poly tunnel ( Siwek and Capecka1999)\. It is important to note that no significant differences were observed in fruit weight in both condition i.e., grown in tunnels and in open field. Net income and cost benefit ratio was maximum when sowing the crop on 30th December under tunnel. This might be due to high market value in off-season RESULTS AND DISCUSSION – Fruit Attributing Parameters

38. An experiment was conducted to assess the effect of different planting time, viz. 15 August, 1 September and 15 September and NPK fertilizer doses, viz. @15:7:16, 20:12:21, 25:17:26 and 30:22:31 kg/ 1000 sq m on bitter gourd ( var.Pusa Rasdar ) with the help of hand cum honey bees pollination under protected condition. The results revealed that the yield attributing traits and fruit nutrients accumulation were significantly influenced by different planting time and level of NPK nutrients. Among dates of planting, 15 August exhibited significant higher values for number of fruits/plant (8.57), fruit diameter (5.96 cm), fruit weight (210.60 g), yield/plant (1.81kg), yield/1000 sqm (72.55 q), accumulation of nitrogen (155.09 mg/100 g), phosphorus (36.58 mg/100 g), potassium (329.17 mg/100 g) , besides accumulation of calcium (14.92 mg/100 g), iron (0.26 mg/100 g) and zinc (0.58 mg/100 g) were found more by content but showing no significant difference statistically in fruits over different planting times. On other hand by the higher dose of NPK @30:22:31 kg/1000 sq m results were found statistically significantly higher values for fruit weight (224.05 g), yield/plant (1.88kg), yield/1000 sq m (75.34 q), nitrogen (231.14 mg/100 g), phosphorus (39.33 mg/100 g), potassium (343.56 mg/100 g), calcium (19.33 mg/100 g), iron (0.31 mg/100 g), but zinc (0.59 mg/100 g) content was found more but sown statistically non significant deference as compared to lower dose of fertilizers. Among the interactions, 15 August planting with NPK dose @ 30:22:31 kg/1000 sq m resulted in significant effects on better yield and its attributes. However, accumulation of nutrients, viz. N, P, K, Ca, Fe and Zn, though recorded higher in this variety of bitter gourd but statistically showed a non-significant difference. The result indicated that the crop sown on 15 August with higher dose of NPK (30:22:31 kg/1000 sq m) deserves being the most promising treatment for bitter gourd cultivation under polyhouse cum protected condition.

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