Roots Sustainable Agricultural Technologies has just released results from a successful pilot on Romaine lettuce — these show a 132% increase in lettuce leaf fresh weight using the company’s proprietary Root Zone Temperature Optimisation (RZTO) cooling technology.
The lettuce growing cycle was reduced by almost half, with the crop ready for harvesting in 27 days.
This follows on from successful RZTO cooling proof of concepts on lettuce using Nutrient Film Technique (NFT) technologies and interim results in medicinal cannabis.
The Romaine lettuce pilot was conducted during the Israeli summer over 27 days between July and August this year, at ROO’s research site in central Israel. Using the hybrid ground source heat exchange version of the RZTO system, lettuce roots were cooled to remain relatively stable around 24 degrees centigrade, despite air temperatures in the greenhouse regularly topping 34 degrees. In comparison, roots of control plantings fluctuated between 28 and 34 degrees.
Cooled lettuce plants had an average fresh weight of 502 grams, compared to an average weight of 216 grams for non-cooled plants. On top of that, marketing weight was achieved in 27 days – compared to seed manufacturer data showing a normal growing cycle range of 30-50 days.