Methyl jasmonate (MeJA) is a plant signaling compound known to influence secondary metabolite production, including phenolic compounds and antioxidants. While many studies have shown MeJA’s effects applied to fruit post-harvest, this study aimed to evaluate its effects applied to the foliage and fruit of strawberries (Fragaria × ananassa ‘Seascape’ and Fragaria × ananassa ‘Ft. Laramie’) before harvest, which has been studied to a lesser extent. The effects were measured by evaluating harvest metrics (number of fruits produced and the total mass of fruit per plant) as well as assays quantifying bioactive compounds related to human health. Strawberries were grown using a deep-water culture (DWC) hydroponics system in a controlled greenhouse environment located in Fargo, North Dakota. Plants were treated with MeJA at varying concentrations (0 mM, 0.25 mM, 0.5 mM, 1 mM) as an aqueous solution, with approximately 15 ml sprayed onto the leaves and developing fruit bi-weekly. Fruit extractions in water and 12% ethanol were analyzed for total soluble phenolics and antioxidant capacity using spectrophotometric assays, while enzyme inhibitory activities were assessed using in vitro biochemical inhibition assays. Results were inconsistent across cultivars with 1 mM MeJA increasing the average mass per fruit by nearly 25% for ‘Ft. Laramie’ plants, with little response and no differences for ‘Seascape’ plants. Bioactive assays produced complicated results, with total soluble phenolics peaking at 0.5 mM MeJA for ‘Seascape’ plants while ‘Ft. Laramie’ plants showed a slightly negative trend of TSP in relation to MeJA concentration for first year plants. Results of antioxidant assays, including ABTS radical inhibition and DPPH radical inhibition will be discussed, as will inhibition of enzymes relating to the management of hypertension and diabetes, including α-amylase, α-glucosidase, and angiotensin-converting enzyme.
