Synergistic Effects of G-GANA and Calcium on Bioactive Compounds, Nutritional Quality, and Antioxidant Potential of Strawberry (Fragaria × ananassa Duch.) Fruits

Abstract

Strawberry fruits are recognized as an important dietary source of vitamin C, phenolic compounds, flavonoids, and anthocyanins, which contribute to their nutritional and functional value. This study evaluated the individual and combined effects of foliar-applied G-GANA, a commercial growth stimulant containing gibberellic acid, naphthalene acetic acid, and glycine, and organic calcium on the growth, yield, fruit quality, and bioactive compounds of strawberry (Fragaria × ananassa Duch.) cv. Rubygem under greenhouse conditions. Plants were treated with G-GANA at 0, 50, and 100 mg L⁻¹ and calcium at 0, 1.5, and 3 mL L⁻¹ in a factorial randomized complete block design with three replicates. The combined treatment of 100 mg L⁻¹ G-GANA and 3 mL L⁻¹ calcium produced the highest leaf area (952.1 cm² plant⁻¹), average fruit weight (13.57 g), total yield (204.48 g plant⁻¹), and marketable yield (92.32%). This treatment also produced the highest total soluble solids (9.13%), total sugars (6.90%), vitamin C (39.57 mg 100 mL⁻¹ juice), total phenolic compounds (91.82 mg 100 g⁻¹ FW), and total flavonoids (22.40 mg 100 g⁻¹ FW). The highest anthocyanin concentration (63.82 mg 100 g⁻¹ FW) was obtained with 100 mg L⁻¹ G-GANA combined with 1.5 mL L⁻¹ calcium. Overall, the combined application of G-GANA and calcium improved strawberry productivity and enhanced the accumulation of nutritionally important bioactive compounds. These findings indicate that integrated foliar application of G-GANA and calcium may be a promising agronomic approach for improving the nutritional and functional quality of strawberry fruits under greenhouse conditions.