Non-Thermal Plasma and Soilless Nutrient Solution Application: Effects on Nutrient Film Technique Lettuce Cultivation

Soilless cultivation is one of the best examples of the sustainable intensification concept due to the high use efficiency of its inputs. Managing the nutrient solution through a closed cycle system represents a crucial objective to be pursued, but the recovery of the nutrient solution requires chemical correction and sanitization. The application of non-thermal plasma (NTP) in agriculture promotes the safety of the nutrient solution, decreasing the use of chemicals. The aim of this study was to evaluate the effects of cold plasma on the nutrient depletion, yield, and qualitative traits of lettuce. A closed soilless system (nutrient film technique) was used to compare different NTP treatments: control, low ionization (LI), and high ionization (HI) in two successive lettuce cycles. No significant differences within the nutrient depletion trends were observed. The treated lettuce's yield was 12% higher than that of the control, characterized by a higher total soluble solid content and a significantly higher electrical conductivity and titratable acidity than the control. The ion content was higher in HI plants, as were the contents of nitrogen, phosphorous, and potassium. In HI plants, the leaf pigments were higher, but no significant changes were observed for the antioxidant content. Cold plasma is a promising strategy that brings benefits to the crop.