Foliar Application of Wood Distillate Protects Basil Plants against Ozone Damage by Preserving Membrane Integrity and Triggering Antioxidant Mechanisms

Ozone (O3) pollution is a critical issue for human health, crop yield, vegetation growth biodiversity, and food safety. Several protection strategies from O3-induced injuries have been proposed for crops. Here, we investigated if the foliar application of wood distillate (WD), a plant-based biostimulant applied once a week (0.2%, v/v) for four consecutive weeks, could have a protective effect against the damage caused by chronic O3 concentrations (80 ppb O3, 5 h day−1 for 28 days) in basil plants (chosen as model horticultural plant). The results revealed that plants exposed to O3 showed severe chlorotic spots localized in the interveinal adaxial surface, chlorophyll loss (−25% compared to controls maintained in filtered air), and membrane impairment as indicated by the significant increase in malondialdehyde content (+62%). Conversely, plants exposed to O3 and treated with WD exhibited a reduction in visible injuries, preservation of membrane integrity, and production of antioxidant compounds such as abscisic and salicylic acids (+21 and +62%, respectively), suggesting a protective effect of WD. This research highlights new results regarding the efficacy of WD in mitigating the negative effects of O3-induced oxidative pressure in basil plants.