In order to overcome the adverse climatic impacts and open-air pest infestations, CSIR-CMERI Extension Centre, Ludhiana has indigenously developed a ‘Retractable Roof Polyhouse Technology’. Dr. Nachiket Kotwaliwale, Director, ICAR-Central Institute of Post-Harvest Engineering & Technology (CIPHET), Ludhiana inaugurated the polyhouse technology on Wednesday at the centre in Ludhiana and dedicated it to the Indian farmers.
Briefing about the technology, Prof. (Dr). Harish Hirani, Director, CSIR-Central Mechanical Engineering Research Institute (ICAR-CMERI) said, “This all-weather structure will have an automatic retractable roof which will be operated based on weather conditions and crop requirements from the conditional database using PLC software. This developed technology will help farmers to cultivate both seasonal and off-season crops which can fetch higher yield, firmer and high shelf-life produce by creating optimal indoor micro-climate conditions compared to conventional open field tunnels and naturally ventilated polyhouses, and also it reduces irrigation and disease problems, low labour requirement, environmentally friendly as it eliminates weedicides use, promote organic food production as it is a viable technology for organic cultivation with reduced cultivation cost.”
Indian farmers face a number of problems such as excessive or insufficient cold, heat, rain, wind, and other factors associated with insufficient transpiration, and also crop losses due to insect pests is about 15 per cent at present and this loss may increase as climate change lowers the plant defence system against insects and pests. To some extent, these problems can be overcome by conventional polyhouse. Conventional Polyhouse has a stationary roof to reduce the effect of weather anomalies and pests. However, there are still disadvantages due to roof covering which sometimes lead to excessive heat, and insufficient light (early morning). Besides this, they are also prone to insufficient levels of CO2, transpiration and water stress. A combination of open field conditions and conventional polyhouse conditions is a more robust way to deal with climate change and associated problems in the future.
Speaking on the occasion, Jagdish Manikrao, a senior scientist who has led the research team on the development of this technology explained that the retractable roof used to manipulate sunlight quantity, quality and duration, water stress, humidity, carbon dioxide levels, and crop and soil temperatures. The cropping area in the retractable roof polyhouse is about 384 Sq. m.
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Highlighting the technology, Director CSIR-CMERI said, “As the scientific experimental data on the advantages of this newly developed polyhouse system are lacking, therefore the cultivation of horticultural crops under both naturally ventilated polyhouse and retractable roof polyhouse for comparing the crop production and produce quality is under progress. With the installation of naturally ventilated polyhouse and retractable roof polyhouse side by side, we can get the required scientific data and by analysing the results we can enhance productivity and the developed facility will be used as a demonstration farm to the farmers.”
Salient features of retractable roof polyhouse technology
The developed retractable-roof polyhouse is an improvement to the current polyhouse design with a retractable roof feature suitable for protecting crops from adverse climatic conditions. It combines the benefit of both the natural outdoor environment and a controlled greenhouse environment to allow growers to extend harvest seasons in order to realise the higher prices, increasing yields which reduce the fixed costs per case and eliminating the supply disruptions due to erratic weather so that growers never lose a customer. It helps in growing organically or chemical-free crops in order to achieve higher revenues and lower production costs
A retractable-roof polyhouse have a roof that can be opened and closed, partially or fully. The grower can open the roof when weather conditions are favourable to plant growth and the roof can be closed when the crops need protection. When the roof is open, a polyhouse of this type provides plants with increased light levels and fresh air.
Crops grown in retractable-roof polyhouse
Vegetables that can be grown include cucumber, cherry tomato, cabbage, capsicum, broccoli, lettuce, bitter gourd, cauliflower, coriander, spinach among other greens along with high-value floriculture – carnation, gerbera and orchids.
Advantages compared to the conventional polyhouse
- Higher yield, firmer, high self-life produce compared to a conventional open field, tunnels and naturally ventilated polyhouses
- Prevents crop overheating by cutting infrared radiation, since the crops are more photosynthetically active than conventional growing methods, the plants tend to better yield and quality
- Trap more heat or can able to heat up the soil and use it as a sink when night temperatures are low
- Better and uniform control on indoor humidity by adjusting the vents
- Uniform air and CO2 exchange from the atmosphere throughout the polyhouse
- Better plant vegetative by manipulating humidity and light
- More viable technology for organic cultivation
- As the plants can able to access direct sunlight can increase the plant density than other conventional systems
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In conventional poly house roof is stationery. The roof is always in the closed position and there are disadvantages due to the covers of polyhouse
- In polyhouse increase in temperature
- Early morning and late afternoon insufficient light
- Insufficient levels of carbon dioxide, insufficient transpiration, water stress and crops are more susceptible to pests and diseases
How does it benefit farmers?
- Farmers can cultivate both seasonal and non-seasonal crops throughout the year which can fetch higher value and income
- Less requirement of pesticide use as the crop is less susceptible to pests and diseases.
- Increase in harvesting period
- Reduced cost of crop cultivation
- Farmers get higher yield and quality of produce throughout the year
- Nursery can be grown before transplanting into the open field
Cost to build a retractable-roof polyhouse
Rs. 1500 to Rs. 3000 per square meter depending on the level of automation from basic to fully automatic depending upon crop requirements and weather changes.
- Resilient to climate changes.
- Automatic control system based on crop requirements and weather conditions.
(All features are based on the claims made by the developers of the technology. Agriculture Post doesn’t assume any responsibility or liability for the same.)