Hormetic Effect of Wood Distillate on Hydroponically Grown Lettuce

The addition of biostimulants to nutrient solutions of hydroponically grown crops to speed up plant growth and improve plant yield and quality has been attracting more and more attention. This study investigated the effects of wood distillate (WD) addition to hydroponically grown lettuce (Lactuca sativa L.) plants. Two concentrations of WD, 0.2% and 0.5%, were added to the nutrient solution, and biometric (i.e., leaf fresh weight, root fresh weight, root length and root surface area), photosynthetic (i.e., chlorophyll a, chlorophyll b, and carotenoid content) and biochemical (i.e., electrolyte leakage, total polyphenols, total flavonoids, and total antioxidant power content) parameters were evaluated. The effects of WD were hormetic, as the 0.2% concentration stimulated biometric and biochemical parameters, while the 0.5% concentration inhibited plant growth. Based on these results, it can be suggested that the addition of 0.2% WD to the nutrient solution has a stimulating effect on the growth of lettuce plants, and could be a successful strategy to boost the yield of crops grown hydroponically.