In hydroponic cultivation nitrogen is delivered to plants as a fertilizer in the form of water-soluble nitrate (NO3). When nitrate uptake exceeds assimilation by the plant, accumulation of nitrate in the plant tissues occurs, in leafy vegetables in the leaves. As a consequence, nitrate content in edible leafy plants often exceeds maximum limits set for example by the EU Commission Regulation No 1258/2011 in Europe.


Natural Resources Institute Finland (LUKE) in collaboration with the University of Helsinki has developed a unique method for reducing nitrate content in leafy salad crops cultivated in greenhouses or plant factories. The method utilizes betaine compounds. Experimental studies have been carried out with three commercially significant lettuce plants; iceberg lettuce, frisee type of lettuce and rocket.


The patented method can significantly reduce the nitrate content of lettuce leaves (up to 40-50%), increase the dry matter content of lettuce plants and to slow down the aging of the leaves, leading to improved product quality.

IPR status

Luke has applied patent rights for the invention. The patent has been granted in Finland (FI128830). International patent rights have been applied using PCT application procedure and national patent application in US. Luke is looking for development partner and offers licensing and sales opportunities.