Akademik Veri Yönetim Sistemi
South African Journal of Botany, cilt.184, ss.580-587, 2025 (SCI-Expanded, Scopus)
Nitrogen (N) is essential for plant growth, while cytokinin (BAP) plays a vital role in cell division. Understanding their effects on thyme helps optimize essential oil production, particularly thymol and carvacrol. This three-year study (2018–2020) evaluated the impact of N and BAP on thyme essential oil yield and composition. The study was conducted as a factorial using a randomized complete blocks design with three replications. The factors included N fertilizer amounts (0, 50, and 100 kg N ha-1) and BAP concentrations (0, 100, 200, and 400 μM). The application of N and BAP significantly increased the essential oil content. The highest essential oil percentage (2.45 %) was achieved with 50 kg N ha-1 and 400 μM BAP, 25 % higher than the control. The highest essential oil yield (77.6 kg ha-1) was obtained with 100 kg N ha-1 and 200 μM BAP, a 39 % increase over the control. In the qualitative analysis of essential oil, 28 secondary compounds were identified. The most important identified compounds were thymol, p-cymene, γ-terpinene, carvacrol, α-terpinene and α-phellandrene. The effects of year, N, BAP and their interaction on the percentage of different essential oil compounds were significant. The highest α-flandrene (2.17 %) was obtained with 200 μM BAP in the third year, and the highest α-terpinene (3.17 %) with 100 kg N ha-1 × 400 μM BAP. BAP increased p-cymene. The highest thymol (65.96 %) was obtained by 400 μM BAP in the second year, while the maximum carvacrol (4.63 %) by 100 kg N ha-1 in the second year. The yield of important essential oil compounds was different among different years. The highest yields of α-flandrene, p-cymene, γ-terpinene, thymol and carvacrol were obtained with 100 kg N ha-1 × 200 μM BAP interaction. The application of 100 kg N ha-1, 400 μM BAP and their interaction significantly influenced on the expression of genes encoding the main compounds of thyme essential oil. These treatments increased the expression of genes encoding α-flandrene (PHS1), γ-terpinene (TPS2) and p-cymene (bphA1), while decreased expression of genes encoding thymol (TPS) and carvacrol (aflD). These findings highlight the complex interplay between N and BAP, indicating that appropriate amounts of these treatments can improve the composition of thyme essential oils.