Physiological traits, fruit morphology and biochemical performance of six old fig genotypes grown in warm climates “Gafsa oasis” in Tunisia

The study assessed the physiological parameters in leaves and the morphological/pomological traits in fruits of six fig cultivars (Ficus carica L.) – Sawoudi, Bayoudhi, Mlouki, Assal, Zidi, and Mozai – which grow in the arid climate of the Gafsa oasis (in the center of Tunisia). These cultivars are distinguished by different peel colors ranging from greenish, yellowish-brown, up to dark purple. Experiments measured chlorophyll and gas exchange in the plant leaves and various morphological, pomological, and chemical parameters, including phenolic compounds and antioxidant enzyme activities of the peel and pulp. The results showed that the Mlouki and Assal cultivars had the highest rates of photosynthesis (Pn) (10.17 and 10.44 μmol CO2 m−2 s−1, respectively). In addition, the fruits of these cultivars showed the highest concentration of sugar in the peel and flesh, as well as the highest values of solid soluble content (22.23 and 20.83 °Bx, respectively). Mlouki had the highest fruit weight (66 g) compared to the other cultivars studied. As for the acidity of the fruit, Bayoudhi showed the highest values (6.56 g MAE 100 mL−1), while the fruits of Assal and Zidi had the lowest acidity values. Biochemical determinations showed that Sawoudi had important enzymatic activity assessed by catalase (10.64 and 12.08 U min−1 g−1 in flesh and peel, respectively) and peroxidase, while Mlouki and Assal fruits showed the lowest values. The results also confirmed that the fig peel had higher antioxidant enzyme activity than the flesh. It can be concluded that the Mlouki cultivar exhibits superior overall quality with the highest weight and sugar content, while the dark-peeled cultivars (Sawoudi and Zidi) show the highest concentrations of phenolic compounds and antioxidant enzyme activities. The characteristics of these cultivars are in line with consumer demands, and therefore farmers can be encouraged to devote themselves to multiplying their cultivation.