Biochemical Quality of Garlic Differs by Accession Provenance and Growing Season Rather than Morphotype

Preservation of plant genetic resources has become crucial for agricultural sustainability, particularly for vegetatively propagated crops like garlic. Modern agricultural practices, monoculture farming, environmental degradation, and climate change have led to genetic erosion, and there is growing interest in traditional garlic varieties, which may harbor superior traits. Despite being an asexually propagated crop, garlic exhibits a diverse range of ecotypes in phenotypic and agronomic characteristics. This study analyzed 77 garlic accessions from Istria and Kvarner, Dalmatia, Continental Croatia, and other countries, examining morphological traits alongside biochemical properties, namely allicin content, total phenolic content (TPC), and antioxidant capacity (with ferric reducing antioxidant power (FRAP) assay, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay). Morphological analysis categorized the accessions into two distinct morphotypes, which did not differ significantly in any biochemical parameter. In contrast, accession provenance was associated with differences in TPC and FRAP, with the highest values in accessions from Istria and Kvarner; in 2018/2019, these reached 820.8 mg GAE/100 g DW (TPC) and 354.6 µmol TE/100 g DW (FRAP), significantly exceeding Continental Croatia (494.1 and 180.4, respectively). This regional pattern varied between the two vegetation years. DPPH and allicin content instead differed between the two vegetation years, with DPPH increasing markedly from 2018/2019 to 2019/2020 (from 358.1 to 892.2 µmol TE/100 g DW in QlG1 and from 380.6 to 836.3 µmol TE/100 g DW in QlG2). These results indicate that, in this collection, morphotype was not a reliable predictor of biochemical quality in garlic and underscore the importance of combining morphological and biochemical assessment in germplasm conservation and breeding programs.