polyhouse,hot bed and humidifier in horticulture under protected cultivation

polyhouse, hot bed and humidifier in horticulture is used in protected cultivation

1. HOT BED

2. DEFINITION One method of raising vegetable seedlings even in cold weather is called the Hot Bed The hot bed is a way or providing extra heat to the soil and growing seedlings in the cold season, so seedlings can be grown ahead of time. This means that vegetables can be grown off season, even in cold climates

3. MAKING Choose a good site for the nursery. This must be easy to protect and maintain, with plenty of sun Dig a trench. The trench should be 1 metre wide, 50cm deep, and as long as you need for the amount of plants to be grown Place a 3 inch thick layer of straw or leaf litter in the bottom of the trench

4. On top of this place a 3 inch layer of raw, fresh cow or horse dung, and wet well On top of the dung place another 3 inch layer of straw or leaf litter Then return a 3 inch layer of the soil dug from the trench Finally put a 3 inch layer of fine, fertile soil (which can be made by mixing compost with the dug out soil)

5. The seed will be sown into this layer of fine, fertile soil In the Hot Bed we can sow seeds direct into the soil, or into leaf pots filled with the same soil. After sowing the seed, cover the bed with a thin layer of finely chopped mulch Finally, the bed is covered with a sheet of plastic. First of all make a bamboo frame on which to hang the plastic Bury the edges of the plastic in the soil around the bed, so air cannot get in

6. INSIDE SHOWN THROUGH CROSS SECTION Heat from the dung helps seeds to germinate 2. The plastic helps to protect growing seedlings from frost plastic thin mulch heat heat seed soil+ compost soil straw cow dung 50cm sun sun seedling plastic

7. HEATING SYSTEMS Pit hot bed Fuel-heated hot bed Electric hot bed Steam/hot-water hot bed

8. MAINTENANCE • W hen the sun is out the plastic can be folded back to irrigate and weed the nursery as required •Replace the plastic in the evening, when the sun goes down • Heat from the dung warms the soil, and the plastic prevents it quickly escaping • When the danger of frost has passed the seedlings in the hot bed can be transplanted into the kitchen garden

9. Species to grow in the hot bed

10. ROLES In cold climates and at high altitudes, for several months over Winter and early Spring there is snow and frost, which prevents seeds germinating and can kill young plants. For this reason seedlings can't be grown until the time for frost has past and the weather warms up. By making a hot bed, seedlings can be grown even in the winter This means that vegetables can be produced 1 or 2 months earlier than usual. There are also economic benefits from this. If vegetables can be raised off season, i.e. ahead of time, they can be sent earlier to the market when prices will be higher

11. POLYHOUSE POLYHOUSE

12. DEFINITION A  polyhouse is a tunnel made of polyethylene, usually semi-circular, square or elongated in shape The interior heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building faster than heat can escape the structure Air warmed by the heat from hot interior surfaces is retained in the building by the roof and wall Temperature ,  humidity and  ventilation can be controlled by equipment fixed in the polytunnel

13. CONSTRUCTION The poly-houses are constructed with the help of ultraviolet plastic sheets, which last for more than five years The basic structure is prepared with bamboos or iron pipes. Iron pipe structure is costly but durable than bamboo The structure is covered with 1501-micron thick plastic sheet Generally the length of the polyhouse is 25-30 feet and width 4-5 feet The direction of the poly-house is always East to West, so that the maximum sunshine is available The house should not be constructed in shade

14. METHOD OF HEATING Heating is required in the winter season. Generally the solar energy is sufficient to maintain inner temperature of poly-house but some times a micro temperature is required to be supplied to some crops. For this a few methods may be followed: i) Constructing a tunnel below the earth of the poly-house ii) Covering the northern wall of the house by jute clothing iii) Covering the entire poly-house with jute cloth during night iv) Fitting a solar energy driven device in the poly-house

15. METHOD OF COOLING In summer season when the ambient temperature rises above 40°C during day time, cooling of poly-house is required, which may be achieved by the following methods: i) Removing the internal air of the polyhouse ii) Sucking external air by putting a fan on iii) Installation of coolers on eastern or western wall not only keeps temperature low but maintains proper humidity also iv) The temperature of the poly-house can be controlled

16. TECHNIQUE The Crops can be grown in pots or in the soil Before sowing the seeds, rotten manure is filled in polythene bags of 10 x15 cm size , along with equal quantity of soil and sand Water is sprinkled on the bags and seeds are sown in the bags Small holes are formed in the bags for easy aeration These bags are kept inside the poly-house till the plants grow to about 10-15 centimeters and are then transferred to pots or earth These plants should be given manure and water from time to time Generally disease does not spread, if at all, a little spray may be required For earning maximum profit through maximum production from the crops grown in the poly-house, their cleanliness and pruning is also very important Luxuriantly growing tomato crop requires sticking or otherwise their plants will fall on the ground and get spoiled

17. USES Polytunnels can be used to provide a higher temperature/humidity than that which is available in the environment but can also protect crops from intense heat, bright sunlight, strong winds, hailstones  and cold waves. This allows fruits and vegetables to be grown at times usually considered off season. Every factor influencing a crop can be controlled in a polytunnel Polytunnels are often used in floriculture and nurseries as the economic value of flowers can justify their expense

18. TEMPERATEREGIONS Polytunnels are mainly used in temperate regions Modern designs allow sowing and harvesting machines to move inside the structures so as to automate production Polytunnels have had a significant effect on the production of strawberries in the United Kingdom Other soft fruits such as raspberries and blackberries are also cultivated in the same way

19. TROPICAL REGIONS In a tropical climate, temperatures are prone to soar above all normal levels In such cases, foggers/misters are used to reduce the temperature This does not increase the humidity levels in the poly house as the evaporated droplets are almost immediately ventilated

20. EXAMPLE For example, in India, the inability to grow tomatoes generates price spikes during the monsoon season This is seen as an ideal time to grow tomatoes in polytunnels , since they providing the ideal climate for the crop In India, the Abhinav Farmers Club grows flowers and organic vegetables in polytunnels

21. HUMIDIFIER

22. IMPORTANCE Plants can't live without water & most plants are mostly composed out of water and the well-being of a plant, depends on the relative humidity of its surroundings Leaves lose water through evaporation through their stomata – small openings in special cells on the leaf surface where gaseous exchange takes place if the relative humidity is too low, a plant will start to give up some of its water into the surrounding air which will result in the plant drying out and  wilting

23. OBJECTIVES Eliminating the application of excess water Soaking and cooling of the propagation medium Temperature and humidity control reduces the stress on cuttings which occurs during intervals of high temperature or low humidity Needed only during daylight hours and are unusual hot night winds

24. REQUIRES THE CONSIDERATION OF FOUR FACTORS Ambient air temperature and relative humidity Humidification rate of incoming air Rate of air exchange Air exchange between cuttings

25. OPERATION Cuttings are maintained under controlled temperature and humidity Temperature is maintained at a determined point by controlling the amount of solar heated air that is exhausted Humidity is maintained as close to hundred percent as possible by humidifying all incoming air Misting by directly humidifying the air around the cutting 50- 70% shading reduces the amount of heat generated during the summer season to manageable levels and still allows ample light for the cuttings The minimum amount of light needed for propagation but reduction of rooting has not been observed with as much as 80% shading

26. REFERENCES https://en.wikipedia.org/wiki/Polytunnel  https ://hort.purdue.edu/ext/HO-053.pdf http://www.jaybird-mfg.com/applications/horticulture/aquafog-and-propagation / Aquafog and Propagation by Daniel C. Milbocker