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  • 27 September 2018 11:54

Root zone cooling technology increases lettuce growth in greenhouse by 132 percent, nearly halves growing time

Australian ag-tech company Roots Sustainable Agricultural Technologies has released results from a successful greenhouse pilot on romaine lettuce showing a 132 percent increase in lettuce leaf fresh weight using its proprietary Root Zone Temperature Optimisation (RZTO) cooling technology.

Australian ag-tech company Roots Sustainable Agricultural Technologies has released results from a successful greenhouse pilot on romaine lettuce showing a 132 percent increase in lettuce leaf fresh weight using its proprietary Root Zone Temperature Optimisation (RZTO) cooling technology. Cooled lettuce plants had an average fresh weight of 502g, compared to an average weight of 216g for non-cooled plants.

In addition, marketing weight was achieved in 27 days – compared to seed manufacturer data showing a normal growing cycle range of 30-50 days.

The pilot was conducted during the Israeli summer over 27 days between July and August 2018, at Roots’ research site in central Israel. Roots’ RZTO system optimises plant physiology for increased growth, productivity and quality by stabilising the plant’s root zone temperature. The technology has received a lot of interest internationally for its ability to help farmers address environmental challenges brought on by ecosystem degradation and pollution, reduced access to water, more severe weather conditions and higher energy prices.

RZTO leverages ground source heat exchange through a closed-loop system of pipes. The lower coils are inserted at a depth where soil temperature is stable and not affected by weather extremes while the upper part of the system is installed at the crop’s root zone just below the soil surface. Cooled water is pumped and discharged through the pipes at the root zone, which stabilises the root zone temperature and mitigates extreme heat.

During the pilot, lettuce roots were cooled to remain relatively stable around 24 degrees centigrade despite air temperatures in the greenhouse frequently topping 34 degrees. In comparison, roots of control plantings fluctuated between 28 and 34 degrees.

Roots’ cloud-based monitoring software enables growers to remotely access online data in real-time from a PC or smart device and analyse system performance using various parameters across the centrifugal pump, heat/cooling pump and header as well as monitor crop performance and root system, air and ground temperatures.

Roots CEO, Dr Sharon Devir said, “These results highlight the many benefits of root zone cooling in modern agriculture including enhanced plant growth, improved quality, shorter growing cycles, greater growth uniformity as well as energy savings compared with traditional greenhouse cooling systems.”

“Cooling the roots of lettuce plants in summer not only significantly increases crop yield but also reduces the growing cycle duration and increase yield uniformity. These benefits together could help farmers plan for increased annual crop production and, therefore, increased income.”

“This latest pilot complements an earlier pilot where Roots’ RZTO technology was used in collaboration with NFT technologies created by Teshuva Agricultural Projects to cool the nutrient temperature of hydroponically grown lettuce. The results are consistent with previous open field lettuce cooling experiments.”

“Our RZTO systems are versatile and can be used to cool the roots of crops in open fields, grow bags, hydroponic and in soil.”

Devir said the company’s unique cooling systems had already been effective in stabilising the plant roots of basil, cucumbers, apricots, cherry tomatoes and medicinal cannabis.

“We are the only company in the world with a commercial root cooling technology. We are therefore optimistic about our ability to generate increased sales, as the results of these pilots conducted in areas that experience weather extremes are analysed by farmers in various markets.”

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