Ascorbic Acid Mitigates Aluminum Stress Through Improved Antioxidant Mechanism in Highbush Blueberry (Vaccinium corymbosum L.)

Ascorbic acid (ASC) is a molecule naturally synthesized in plant cells, protecting against abiotic stresses by reducing reactive oxygen species (ROS), which cause oxidative damage. Aluminum (Al) toxicity is the major limiting factor on crop productivity in acidic soils, increasing ROS within cells and impairing the growth and development of plants. Exogenous antioxidant applications are an effective strategy to promote tolerance to abiotic stress. The objective was to evaluate the effect of foliar ASC applications (0, 50, 100, 200, and 400 mg L⁻¹ ASC) and their interaction with Al toxicity (0, 400 µM Al) in Star, an Al-sensitive cultivar of highbush blueberry. Significant increases of 1.6-fold in growth were observed in roots and leaves under treatment with 200 mg L⁻¹ ASC. In the same treatment, increased pigments and antioxidant activity (~1.2- to 2.3-fold) were observed concomitant with reduced lipid peroxidation. Positive correlations between organic acid exudation, the ASC/DHA ratio, and calcium levels were observed, whereas a negative correlation between lipid peroxidation and dehydroascorbate (DHA) was observed. Foliar ASC application also increased the ASC/DHA ratio in leaves and enhanced 2.2-fold organic acid exudation in the 200 mg L⁻¹ ASC treatment. The results suggest that foliar ASC applications improved redox balance and underscore the potential of ASC as a practical solution to enhance resilience in Al-sensitive plants.