The effect of environmental and genotypic factors on essential oil rate, composition, and compliance with standards in clones of Istanbul oregano ( Origanum vulgare subsp. hirtum )

OpenAlex İngilizce

Origanum vulgare subsp. hirtum (Istanbul oregano) is one of the most economically important oregano species, widely used in the spice, pharmaceutical, and cosmetic industries due to its high essential oil content, particularly rich in carvacrol. This study aimed to evaluate the essential oil traits and quality characteristics of 20 Istanbul oregano C clones and two registered cultivars developed through clone selection. Field trials were conducted under Mediterranean climate conditions (Aydın and İzmir, Türkiye) during 2021-2022 using a RCBD with three replications. Essential oil rate (EOR) was measured by water distillation, while essential oil composition (EOC) was analyzed by GC- MS and compared with ISO 13171 (2016) standards. The results highlighted a significant influence of genotype × environment (G × E) interactions on EOR and EOC. EOR values ranged from 4.1% to 11.73% across environments, with C-417 and D-343 consistently exceeding the population average. Carvacrol was the dominant compound (62.26-87.24%), while thymol, p-cymene, and γ-terpinene also showed considerable variation across genotypes and environments. Notably, A-419 displayed the highest carvacrol levels in both sites, whereas several genotypes (D-343, C-417, A-419, A-420) successfully combined high EOR with stable oil profiles. Almost all genotypes complied with ISO 13171 (2016) standards, underlining their industrial potential. In conclusion, the findings demonstrate that both environmental and genetic factors, as well as their interaction, play a decisive role in shaping yield stability and EOC in Istanbul oregano. Superior genotypes identified through clone selection emerged as promising variety candidates for future breeding programs, sustainable cultivation practices, and commercial exploitation.