Diversity of phenolic compounds, antioxidant capacity, and mineral element content in four fig cultivars (Ficus carica L.) and their correlation with the rooting of hardwood cuttings

Abstract

We investigated the phenolic compound profile, antioxidant capacity, rooting of cutting and fruit mineral concentration on 15-year-old trees of four Iranian figs (Ficus carica cvs. “Siyah”, “Kashki”, “Shahanjir” and “Sabz”) planted under rain-fed conditions with different fruit skin color, as well as the correlation between these traits. The range of TSS and antioxidant capacity of fruit (without significant differences) was 75.3–76.7°Brix and 87.9–90.3 DPPHsc %, respectively. “Kashki” had the highest total phenolic (TP) (mg GAE/100 g dw) in both the fruit (1964) and the stem bark (1702) and “Sabz” had the lowest flavonoid content (µg CE mg−1 dw) in the fruit (652.3), leaf (1274.5), and stem bark (1501.9). Although the rooting percentage of cuttings was similar in “Siyah”, “Shahanjir”, and “Sabz”, the lowest rooting percentage (62.7%) and the lowest polyphenol oxidase enzyme (PPO) activity (42.5 U.mL−1) were in “Kashki”. Rooting of the cuttings had a direct correlation with PPO activity and catechin and a negative correlation with the TP, vanillin and trans-ferulic acid concentration in cutting bark. These results showed that the fresh cultivar such as “Shahanjir” with outstanding characteristics, such as high potassium and antioxidant content of fruits and good rooting of the cuttings (97.2%) can be recommended for the development programs of light-colored fresh figs. On the other hand, there were two cultivars, “Siyah” and “Kashki” with dark fruit color; due to their content of TP, total flavonoid, quercetin, trans-ferulic acid and high calcium content in the fruit, these should also be considered.