From theory to practice: Optimizing photosynthesis

Deep-Dive into Ventilation, Screening Strategy, and Steering on Plant Temperature

LetsGrow.com and MJ-Tech first worked together on a shared project in 2023, when we joined forces to conduct research to improve climate conditions by using high-pressure fogging and data-driven decision-making.

This collaboration comes naturally, as LetsGrow.com is a company specializing in Data-Driven Growing. Helping to grow efficiently and sustainably by making intelligent use of data and delivering analysis and advice that increases productivity. For over 30 years MJ-Tech has been installing A quality high-pressure fogging (also known as misting) solutions for the international horticultural sector and supporting to ensure the best usage and results.

The trials took place in a production company in Canada, where they produce bell-pepper in a 16-ha greenhouse. The company’s owner and grower recognized the benefits and possible impact on their production quality, yield, and operational expenses, which is why they decided to learn the system and understand how to use it as best as possible; when is the right time to fog, what impact will fogging have on the crop, should other aspects be adapted (e.g., ventilation, screening, etc.) when applying fogging, and more.

 To answer these questions, the team planned a multiple-year research divided into trials. Following from that, a 3-part whitepaper series has been written, discussing the trial’s background, goals, results, and future plans. This article announces the 2nd whitepaper that was recently released.

In the research, two identical compartments were studied under the same outdoor conditions and plant growth stages. The key difference was that compartment 3 was equipped with an MJ-Tech high-pressure fogging system, controlled by a Hoogendoorn climate computer. Both compartments implemented in December 2023 Intelligent Ventilation from the Intelligent Algorithms by Hoogendoorn Growth Management, to optimize climate conditions, enhance photosynthesis, and increase fruit weight and production/m² by supporting energy, water, and assimilate balance.

This trial used a high-pressure fogging system, which injects 3 to 5 micron droplets at 100 bars into the air, facilitating the transformation from liquid to gas and converting sensible energy into latent energy. This system increases humidity and lowers the temperature in greenhouses while maintaining the same enthalpy levels. By keeping plant stomata open, high-pressure fogging enhances photosynthesis and transpiration, improving water use efficiency and preventing water stress. Properly timed (start-stop) and controlled fogging ensures moisture evaporates before reaching plants, reducing the risk of diseases. Adjusting ventilation rates and using sensors to monitor various environmental factors can optimize greenhouse conditions, minimizing CO2 loss and maximizing photosynthesis.

Below are a few figures taken from the whitepaper that are discussed in depth in the report. Nevertheless, already without too many explanations, the figures talk for themselves about the positive impact data-driven growing combined with high-pressure fogging can have.

This whitepaper focuses on explaining the physics behind the control of misting in combination with showing the differences in ventilation, plant temperature, and screening between the misting and non-misting compartments. As discussed in the previous whitepaper, high-pressure misting can offer several beneficial results. To harvest those benefits and translate them to production and fruit quality increase, a combination with proper greenhouse equipment control (e.g., ventilation) needs to be made.

Figure K. Maximum plant temperature difference (°C) between compartments 1 (non-misting) and 3 (misting) during periods that the high-pressure misting system was active. Plant temperature in the misting zone is lower during the growing cycle.

Figure H. Average ventilation wind side (%) for 1 (non-misting, light blue bar) and 3 (misting, dark blue bar) during periods that the high-pressure misting system was active.

We are collaborating with growers, to find an individual strategy for them, to make sure they are able to correctly operate and maximize the benefits from Intelligent Algorithms such as Intelligent Ventilation and Temperature (Hoogendoorn Growth Management) in combination with the high-pressure fogging system, supported by data analysis from LetsGrow.com.

All in all, the whitepaper discussed many aspects around the theory, trial setup, analysis, and results, application setting, climate, and more.

Would you like to learn more about the results? Use the links to request the full 2nd whitepaper file on either the MJ-Tech website, or LetsGrow.com. 

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