Greenhouses/nethouses are designed based on environmental factors such as temperature, sunlight, relative humidity, carbon dioxide, wind speed and direction, rainfall properties and availability of local materials, including plastic used as cover, ultraviolet stabilized polythene film with long-lasting resistance to the sun’s ultraviolet rays. That is 0.2 mm. thickness and width of 7 meters available in the market are used. Apart from this, its frame is made of iron, wood, bamboo, cement pillars, KPVC. Made from pipe. Iron is mostly used now.
In addition, they are fitted with other climate control equipment such as heaters for heating and cooling systems for cooling, usually evaporative. By increasing such humidity to cool the indoor environment, exhaust fans are arranged in front of the cooling pad which, when turned on, cool and humid air enters inside and cools the environment.
Sodium, halogen and mercury lamps are often used to provide artificial light to plants. Indoor plants are usually watered using modern and economical methods such as drip or fountain systems.
Can be used properly. By fitting a thermostat, the temperature can be automatically maintained at a comfortable level. All these things are kept in view of the value and importance of the crops grown inside. The minimum height of the greenhouse/nethouse should be such that a person can easily move around in it.
Suitable crops:
(1) Nursery: Vegetable seedlings, pickled cucumber, cherry tomato etc
(2) Vegetables : Tomato, Capsicum, Spinach etc
(3) Flower plants: rose, shewanti, gerbera, carnation, anthurium, orchid etc.
Method of cooling the greenhouse:
Cooling of greenhouses/nethouses by evaporation is a commonly used method. In this method, the heat in the greenhouse is used to evaporate the moisture entering inside, thereby reducing the temperature inside, for which the following two methods are used.
(1) Fan and pad cooling method : In this method, one wall (pad) of the greenhouse / nethouse is made of poppy straw or similar prepared walls. while on the opposite side, The hot air coming from outside the greenhouse will cool and the hot air around this pad in the greenhouse will also cool. So gradually the cooled air inside from the pad will spread towards the fan and the warm air from the fan will be blown out by the fan.
(2) Fogging method: Very small droplets of water are dispersed in the form of a shower by means of a very high pressure pump with nozzles at different places inside. Due to which the air in the greenhouse gets cold and the temperature comes down.
Adding carbon dioxide to greenhouses:
Crops grown in greenhouses require carbon dioxide for sufficient photosynthesis. If the amount of carbon dioxide is artificially increased in the interior than the carbon dioxide in the air, the production can be increased due to the increase in the process of making food through photosynthesis in the plants, so the recommended amount of carbon dioxide should be supplied to the greenhouse as per the requirement of that crop.
(1) Growing plants directly in soil: In this method Plants are grown directly in the soil. Keeping minimum distance between two rows and between two plants in a row can accommodate more plants and make the greenhouse easier to work with is Generally, two rows are planted with a short distance between them and the next two rows are planted at a slightly greater distance. So that the plants can be irrigated by drip method in two rows simultaneously and in the space between such twin rows it is easy to harvest vegetables and fruits and do other operations. The method commonly adopted is tomato, capsicum, chilli, rose and gerbera.
(2) Growing plants in soilless medium: In this method, boxes of specific length, width and height are arranged in a straight line on the ground. Then plants are grown in it keeping one or two rows at certain distance. As these boxes store all the water, they are supplied with drip irrigation along with all the necessary fertilizers and nutrients. This method is being used especially for growing long duration crops like tomato, capsicum chilli, rose and gerbera and it gives very good yield.
(3) Hydroponics method: In this method, a solution is prepared by dissolving fertilizers and necessary nutrients in water. This solution is used by different methods by growing plants directly in it. As this method is expensive and labor intensive, it is rarely used.
Important factors for conservation agriculture:
Compared to other crops, vegetable crops are more sensitive, yielding results in terms of quantity and quality as far as crop factors can be controlled. Factors affecting seed germination, growth and flower and fruit development of such crops are as follows:
- Temperature
- Sun light
- Relative humidity