Root-zone cooling technology doubles lettuce yields, speeds growth

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Root-zone cooling technology doubles lettuce yields, speeds growth

An Australian company says its root-zone cooling technology has resulted in a huge increase in greenhouse lettuce yields and faster growing times.

Roots Sustainable Agricultural Technologies Limited (ASX: ROO) carried out a pilot trial of its proprietary RZTO cooling technology at its research site in central Israel over the summer.

It found that cooled lettuces had an average fresh weight of 502g compared to an average weight of 216g for non-cooled plants - marking a 132% increase.

It also said this was achieved in 27 days, compared to seed manufacturer data showing a normal growing cycle range of 30-50 days.

Using the hybrid ground source heat exchange version of Roots’ RZTO system, lettuce roots were cooled to remain relatively stable around 24ºC despite air temperatures in the greenhouse frequently topping 34ºC. In comparison, roots of control plantings fluctuated between 28ºC - 34ºC.

The technology involves a closed-loop system of pipes. The lower part are coils installed at a depth where soil temperature is stable and not affected by weather extremes, and the upper part in the target crop’s root zone just below the soil surface.

Water flowing through the lower pipes is charged by the soil’s stable temperature. The heated (or cooled) water is pumped through the pipes installed in the root zone, where the heat (or cold) is discharged.

"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," said Dr Sharon Devir, Roots CEO.

"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."

He said this latest pilot complements a previous trial reported in July where the 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, he said.

"Our RZTO systems are versatile and can be used to cool the roots of crops in open fields, grow bags, hydroponic and in soil," he said, adding the technology has so far been also effective in stabilizing the plant roots of basil, apricots 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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