This research was aimed at evaluating the production of leaves' phytomass, the content and quality of Mentha x gracilis Sole essential oil with four potassium (K) levels (276, 414, 552 e 690mg L-1) under hydroponics, on "NFT" system (Nutrient Film Technique). A completely randomized design was used with five replications. Stakes of matrix plants were rooted in phenolic foam for 20 days in a nursery, being then transferred to final production benches. Harvesting occurred at 49 days after transplanting. Leaves were separeted and weighted to determine fresch phytomass, and utilized for oil extraction in a Clevenger apparatus. The analyses of oil chemical constitution were performed in Gas Chromatography connected to a Mass Spectrometer. The K concentrations affected leaves fresh phytomass, content and quality of the essential oil. The K level maximum showed increase of essential oil yield, but decreased the fresch phytomass accumulation, decreasing the oil yield by plant and linalool quantity, the main constituent of this chemotype. The K concentration suggested for the greatest yield of M. x gracilis, under hydroponics, doesn't surpass 276mg L-1 in nutritive solution.
Mentha x gracilis; Lamiaceae; linalool; volatile oil
