The aim of greenhouse farming is to create controlled environments for optimum plant development and growth without being limited to external climatic conditions and seasonal constraints.
Plants rely heavily on the right temperature, CO2 concentration, light intensity and humidity to perform vital processes like photosynthesis, respiration and transpiration for optimal growth. It then goes without saying that maintaining a consistent, controlled environment will lead to significantly higher, and better quality crop yields, while having a major positive effect on the profits of your growing business.
Greenhouse screens are one of the more affordable elements of your entire greenhouse solution but they play a massive role in creating controlled environments which result in greater productivity:
Greenhouse screens can be used to control the intensity or radiation levels of sunlight through shading which means that temperatures remain at optimum levels for photosynthesis as discussed next.
Plants use CO2, water and sunlight to manufacture carbohydrates during photosynthesis. During respiration, plants convert these carbohydrates into plant tissue and also use them to maintain plant health.
If temperatures are too high, photosynthesis slows down which means that more emphasis is placed on using carbohydrates for maintaining plant health and therefore tissue formation is sacrificed.
Recent studies show that the screens can reduce the plant temperature by 2-3 °C lower than the internal greenhouse temperature. Studies have also been done comparing the use of shade screen vs white-wash of the greenhouse roof. The greenhouse equipped with a shading screen yielded 25% more marketable tomato product
Another benefit of greenhouse screens is that heat can be trapped at night to stimulate further plant growth while protecting the plants from damage caused by frost.
Humidity levels that are too high or too low inside a greenhouse can affect plant health by causing nutrient deficiencies (transpiration is affected negatively) and increasing plant susceptibility to fungal infections.
Plants radiate heat causing warm air to rise containing water vapor. Even though greenhouse screens/curtains are used to control temperature of the greenhouse, they allow water vapour caused by plant radiation to pass through which means that condensation can occur on the cold roof of the greenhouse allowing the drainage system to remove excess water. This prevents the buildup of moisture in the greenhouse avoiding dangerous levels of humidity.
Even if optimum CO2 levels are reached, successful greenhouse farming is limited to the degree at which other climatic conditions are favorable such as optimum light, temperature and humidity. Using screens in greenhouses helps to produce the desired controlled environments, maximizing the effect of CO2 in the greenhouse.
Depending on the conditions outside your greenhouse, you may need to invest significantly in energy for heating or cooling your greenhouse. However, the good news is that greenhouse screens can hugely mitigate these greenhouse energy costs.
For example, greenhouse screens can be used to trap heat when closing them at night. Therefore, less energy is needed to raise the temperature of the environment. This is especially good news for South African farmers who are at the mercy of rising coal and energy prices.
With all the variables for optimum plant growth being challenged by fluctuating environmental conditions on an ongoing basis, it can be difficult to keep your finger on the pulse and implement manual adaptations on the fly to control the climate inside your greenhouse.
Using technology to detect changes in climatic variables settings on your greenhouse curtains can be adjusted through automation to provide peace of mind that your environment is being controlled with precision.
As you can see, greenhouse screens or curtains are super useful and effective for creating the ideal growing conditions for your crop of choice, no matter what external conditions you are facing. If you need more guidance, feel free to reach out to us at info@bosmanvanzaal.co.za. With almost a century of experience internationally, we are recognised as South Africa’s market-leading commercial greenhouse engineers with the in-house knowledge and expertise to bring your vision to life in every crop and protected horticulture need.
Bosman Van Zaal has 90 years of experience in the development and construction of greenhouses and over 40 years' experience with technical systems for international horticulture.
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