Elicitor-Driven Changes in Harvest Quality of ‘Calabacita’ Figs Under High-Density Production

Fresh figs are characterised by high perishability, leading to a limited postharvest shelf life. Consequently, preharvest elicitor application strategies have been explored to enhance their quality and storability. During the 2022 and 2023 seasons, figs (cv. Calabacita) grown under high-density conditions were treated with oxalic acid (OA; 1 and 2 mM), melatonin (MEL; 0.1 and 0.5 mM), and γ-aminobutyric acid (GABA; 10 and 50 mM) through foliar sprays applied two or three times. Fruits were harvested at commercial maturity and analysed immediately after harvest. Physicochemical and bioactive parameters were determined. Analysis of variance was used to assess treatment effects, and t-tests were used to evaluate differences in the number of applications and between seasons. Significant seasonal effects were observed, whereas no cumulative effect from repeated applications was detected. OA at 2 mM increased fruit weight (37.9 g) and size (42.5 mm) and delayed ripening. MEL treatments enhanced sugar accumulation (100.1 g kg−1 and 96 g kg−1 of glucose and fructose, respectively), while GABA treatments were associated with a more advanced maturity stage. Notably, OA (2 mM), MEL (0.5 mM), and GABA (50 mM) significantly increased enzymatic antioxidant activity by an average of 24% and non-enzymatic antioxidant capacity by around 17% in general terms. These results indicate that preharvest elicitor application is a promising and eco-friendly approach to improve the nutritional value and overall quality of fresh figs.