Genotype × Environment Interactions Govern the Biochemical Composition and FTIR Spectral Fingerprint of Fig (Ficus carica L.) Seed Oil

Background/Objectives: Fig (Ficus carica L.) seed oil is an emerging by-product with promising nutraceutical properties, yet the influence of genotype × environment (G × E) interactions on its biochemical composition remains poorly understood. This study aimed to evaluate compositional variability among fig genotypes, identify metabolic trade-offs affecting oil quality, and assess the potential of FTIR-ATR spectroscopy as a rapid tool for varietal authentication and discrimination.

Methods: Thirty-seven fig genotypes cultivated in Morocco were investigated over two consecutive harvest years (2023–2024). Oil yield, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities (DPPH and ABTS assays) were determined using conventional analytical methods. FTIR-ATR spectroscopy was employed to characterize spectral fingerprints, while analysis of variance (ANOVA) and principal component analysis (PCA) were used to evaluate the effects of genotype, year, and G × E interactions.

Results: Significant variability was observed among genotypes and between years for all measured traits (p < 0.001). TPC ranged from 16.5 to 115.1 mg GAE/100 g oil and decreased by approximately 36% from 2023 to 2024, while TFC followed a similar trend. In contrast, DPPH radical-scavenging activity increased by 34% in 2024, whereas ABTS activity declined by 18.6%. Mean oil yield decreased from 26.7% to 21.2% between years and showed a significant negative correlation with phenolic accumulation (r = −0.49, p < 0.001), suggesting a trade-off between lipid biosynthesis and secondary metabolism. FTIR-ATR analysis revealed diagnostic spectral markers, with significant G × E effects detected across key absorption bands. PCA explained 75.4–84.5% of the total variance and successfully discriminated both harvest years and genotypes. ‘Dottato Perguerolles’, ‘VCR 276/49’, and ‘Ferqouch Jmel’ emerged as the most stable and promising cultivars.

Conclusions: Fig seed oil composition is strongly influenced by both genetic background and environmental conditions. The integration of biochemical analyses with FTIR-ATR spectroscopy provides an efficient approach for cultivar discrimination and supports the selection of stable, high-value genotypes for nutraceutical applications.