Fruit compositional differences in ‘Albion and ‘San Andreas’ strawberries grown in a hydroponic system

Day-neutral strawberry cultivars ‘Albion’ and ‘San Andreas’ were cultivated hydroponically in a climate-controlled greenhouse (temperature and light regulated) to assess fruit quality and anthocyanin composition, which are important attributes for flavor and color (visual appeal), respectively. Fruits were collected from February 6, 2023, until May 18, 2023, at Auburn University, Alabama. Soluble solids content (SSC), titratable acidity (Tacid), pH, total phenolics (TPC), and anthocyanins [total anthocyanins (TAC), cyanidin-3-glucoside (C3G), pelargonidin-3-glucoside (P3G), pelargonidin-3-rutinoside (P3R), pelargonidin-3-malonylglucoside (P3M)] were determined from the juice of thawed frozen fruits. Average fruit mass (FM) (kg harvest-1) was similar between cultivars. Cultivars were similar for SSC, Tacid, TPC, TAC, and the major pigment (P3G) when averaged across DAT. Pelargonidin-based pigments predominantly characterized the anthocyanin profile.  Minor pigments differed, with more C3G (mg 100 g fresh weight-1) in ‘Albion’ than in ‘San Andreas’ (0.39 and 0.18, respectively), whilst ‘San Andreas’ had more P3R (mg 100 g fresh weight-1) than ‘Albion’ (2.26 and 1.81, respectively). Plant age [expressed as days after transplanting (DAT), non-replicated] influenced SSC, Tacid, and most of the anthocyanins. Fruit mass, Tacid, and SSC were higher in plants at 140 DAT (early spring), but lower in plants at 180 DAT (late spring), indicating a potential plant age effect on fruit productivity and quality. Principal component analysis (PCA) indicated robust positive correlations between TAC, C3G, pelargonidin anthocyanins (P3G, P3R, P3M), and FM, whereas phenolic content exhibited weaker or negative interactions with pelargonidin pigments. Our results indicate that anthocyanin profile differences with these day neutral strawberry cultivars persisted in hydroponic production over an extended harvest season.