Phenolic Compounds and AOX Activities in Chard (Beta vulgaris L. var. Cicla) Elicitated With Hydrogen Peroxide In Open Field

Objective: The main objective of this study was to enhance the functional food properties of Swiss chard (Beta vulgaris var. cicla L.) through controlled elicitation using hydrogen peroxide (H₂O₂). Theoretical Framework: Chard is a highly demanded leafy vegetable due to its low cost, ease of production, and high nutritional value, containing minerals, soluble sugars, fatty acids, vitamins, and phenolic compounds. Plants respond to these stressors leading to the production of antioxidant (AOX) compounds that mitigate stress-induced damage. Hydrogen peroxide (H₂O₂) exogenous application can stimulate specialized metabolite production and enhance antioxidant capacity in plant tissues. Method: Swiss chard plants were subjected to seven H₂O₂ concentrations. It was evaluated DPPH• and ABTS•+, Catalase (CAT), Superoxide dismutase (SOD), Phenylalanine ammonia-lyase (PAL) enzymatic activity, total phenolic content and concentration, and Nitrate concentration. Results and Discussion: The 75 mM H₂O₂ treatment acted as a bio-stimulant, significantly increasing antioxidant activity and the synthesis of phenolic compounds without negatively affecting nitrate concentration. Enzymatic activity of PAL was enhanced, indicating an upregulation of secondary metabolism, leading to higher levels of phenolic compounds and antioxidants in the plant. Research Implications: This study provides an alternative approach to improving leafy vegetable quality using a non-toxic, cost-effective elicitor (H₂O₂). The results suggest that controlled H₂O₂ application could be implemented in agriculture to enhance plant metabolic responses, leading to higher antioxidant content and better functional properties in crops. Originality/Value: This study demonstrates a novel bio-stimulation approach that does not compromise nitrate concentrations, addressing concerns related to excess nitrate accumulation in leafy greens.