Evaluating Seawater and Wood Distillate for Sustainable Hydroponic Cultivation: Implications for Crop Growth and Nutritional Quality

The adoption of innovative cultivation methods, such as hydroponics and aeroponics, is gaining attention due to the unprecedented demand for food that an increasing population is posing on agricultural systems, exacerbating the pressure on already limited arable land. Seeking sustainable and circular economy solutions is imperative, aiming to optimize water consumption and enhance crop yields and quality without resorting to synthetic chemical fertilizers. This study investigated the use of seawater at various concentrations as a base for nutrient solutions, with and without the addition of a natural biostimulant, wood distillate (WD). Four seawater (SW) concentrations (0, 3, 6, and 12%) and two wood distillate concentrations (0 and 0.2%) were applied to assess their impacts on lettuce growth. Findings reveal that seawater at low concentrations (< 6%) serves as an effective water-saving strategy, despite the reduction in the plant ascorbic acid contents. The addition of WD did not inflate growth; in fact, the results obtained are comparable to that of the controls for each concentration of seawater, except at the highest concentration (12% SW), resulting in reduced fresh leaf weights and root areas. Significantly, there was a notable increase in the ascorbic acid contents in all plants grown with WD. Moreover, the WD increased the leaf concentrations in Ca, Mg, P, and K, indicating the higher nutritional value of the crop. This research highlights the potential of combining seawater and WD for sustainable and efficient plant cultivation, suggesting new strategies for exploration across diverse plant species and hydroponic applications.