Phenolic and Physiological Characterization of Turkish Garlic (Allium sativum L.) Genotypes across Diverse Agro-Ecological Regions

This work aimed to evaluate the biological and biochemical variability of 11 Turkish garlic (Allium sativum L.) varieties from various agro-ecological regions of Türkiye and emphasized their potential as useful genetic resources. 28 phenolic compounds were studied by high-performance liquid chromatography (HPLC), exhibiting significant variation in total phenolic content and compound-specific accumulation. A few major stress-related compounds, including salicylic acid, trans-ferulic acid, rutin, caffeic acid, and syringic acid, showed high accumulation in specific genotypes, reflecting genotypic divergence and environmental adaptation. Except for secondary metabolites, other important photosynthetic and antioxidant traits like chlorophyll a, chlorophyll b, total chlorophyll, total carotenoid, phenolic content, and antioxidant activity were also quantified. These parameters provided further details on the concerned landraces’ physiological vigor and tolerance to abiotic pressure. For instance, genotypes R10, R9, and R8 had high pigment content and antioxidant activity and hence provided a well-orchestrated defense and photosynthesis response against fluctuating climatic pressures. Multivariate analyses including PCA, HCA, radar chart mapping, and TOPSIS separated top garlic genotypes based on integrated biochemical and physiological traits as R10 (Şanlıurfa, Southeastern Anatolia), followed by R9 (Konya, Central Anatolia) and R8 (Balıkesir, Marmara). These landraces exhibited metabolite profiles indicative of efficient stress adaptation to their native agro-climatic regions. Correlation analysis revealed significant co-regulation between phenylpropanoid and flavonoid pathways, suggesting coordinated physiological responses to environmental factors. Overall, integrative assessment of phenolic composition, chlorophyll and carotenoid pigments, and antioxidant capacity offers a comprehensive understanding of intraspecific variation, supporting genotype selection and breeding for enhanced nutritional quality and climate resilience.