Phytotoxicity assessment of sodium for lettuce grown in NEREA®-based hydroponics


A preliminary trial was carried out to evaluate the sodium content and solubility of NEREA®, and eventual uptake by the plant, when used as a media substitute for lettuce grown in a greenhouse using a hydroponic Nutrient Film Technique (NFT) system.


In a previous trial with AETIC, the NEREA® product demonstrated capacity to be used successfully as a hydroponic medium to grow lettuce. From that trial, very high levels of sodium were noted in the NEREA® product, and thus may lead to toxicities within produce grown in NEREA®.


The Horticultural & Environmental Sciences Innovation Centre team at Niagara College trialed parallel crops of lettuce seedlings grown in the Niagara College (NC) greenhouse located in Niagara-on-the-Lake (NOTL), Ontario, comparing sodium concentration in both the nutrient solutions and lettuce leaves grown in standard Oasis® cubes, with those grown in NEREA® as a substrate. The results of this study have shown that NEREA®, both in raw form and the leachate from NEREA®, is higher in sodium content compared to the amount measured in a standard hydroponic fertilizer recipe. Sodium uptake into the leaves of lettuce, Lactuca sativa ‘Salanova’, was higher in those grown in NEREA® than in the standard Oasis® rockwool. While the sodium level within the nutrient solution and within the leaves at harvest were considered higher than recommended, there were no visual negative effects of this excess. In fact overall, the lettuce grown in NEREA® was more advanced in size, leaf count, and root mass than the lettuce grown in Oasis®.

Funding: The project is being funded in part by the Niagara College-led Greenhouse Technology Network (GTN), through the Federal Economic Development Agency for Southern Ontario (FedDev Ontario).