Physiological and Biochemical Responses of Cucumber and Maize Seedlings to Acetylsalicylic Acid: The Protective Role of Exogenous Ascorbic Acid

The aim of this study was to assess the effects of acetylsalicylic acid (ASA) on the early development of cucumber (Cucumis sativus L.) and maize (Zea mays L.) and to determine whether exogenous ascorbic acid (AsA) could modify their responses. In a 14-day pot experiment, ASA was applied at nominal doses of 0, 1, 10, 100, 500, and 1000 mg kg−1 of soil dry weight (DW), and AsA was applied at concentrations of 0, 1, and 2 mM. Germination, growth, biomass, photosynthetic pigments, chlorophyll fluorescence, and selected oxidative stress markers were assessed. Plant responses varied depending on the species and exposure treatment. ASA had no statistically significant effect on seed germination rate (GR). Only the highest ASA dose (1000 mg kg−1 of soil DW) resulted in a 6% reduction in cucumber fresh biomass and a 13% increase in dry matter content. At this dose, total chlorophyll content in cucumber decreased by approximately 24% relative to the control. The addition of 2 mM AsA helped maintain chlorophyll content at a level close to that of the control and increased cucumber shoot length from 8.2–8.8 cm in treatments with ASA alone to 9.7–10.0 cm in selected combined treatments. In most treatments, Fv/Fm remained close to 0.80. Exogenous AsA was also associated with reduced H2O2 and MDA accumulation and increased the content of reduced AsA in leaf tissues in selected treatments, although its effects differed between the two species. These findings indicate that AsA can both stimulate seedling growth and alleviate selected physiological disturbances associated with ASA exposure; however, the observed effects cannot be unequivocally attributed to a specific detoxification mechanism.