The changes of carvacrol content and essential oil yield of Satureja khuzestanica Jamzad in response to different fertilizer sources

This research aimed to evaluate the combined effects of chemical, biological and organic fertilizers on several features of Satureja khuzistanica. As an aromatic plant with medicinal properties, endemic to Iran, S. khuzistanica was studied for essential oil (EO%) and composition. Spanning for two growing seasons (2017–2019), the experiments involved 13 nutritional treatments, ie, (a) control (C), (b) nitrogen, phosphorus and potassium (NPK; 50-25-25 Kg ha⁻¹), (c) cattle manure (CM₃₀; 30 ton ha⁻¹), (d) CM₆₀ (60 ton ha⁻¹), (e) CM₃₀ + NPK, (f) CM₆₀ + NPK, (g) vermicompost (V₅, 5 ton ha⁻¹), (h) V₅ + NPK, (i) Glomus mosseae (GM), (j) Glomus Intra (GI), (k) sulphur (S₀; 0 Kg ha⁻¹) + thiobacillus (T), (l) S₂₅₀ + T (sulphur: 250 Kg ha⁻¹, ) and (m) V₅ + T. At full flowering stage, samples were taken from aerial segments of plants in all treatment groups. After shade-drying, the samples were hydro-distillated to obtain essential oil (EO) and were then evaluated by gas chromatography–mass spectrometry (GC–MS). The interaction between year and fertilizer, as two treatments, had a significant effect (P ≤ 0.01) on the oil percentage, oil constituents and essential oil yield (EO.Y) of S. khuzistanica. GM and S₀ + T caused the highest oil percentage in the first (3.7%) and second year (3.9%), respectively. V₅ + NPK and V₅ + T resulted in a substantial rise in EO.Y in the first (30.4 kg ha⁻¹) and second year (64.3 kg ha⁻¹), respectively. Carvacrol was highest in the first (92.1%) and second year (95.2%), as a result of using V₅ + T and NPK treatments, respectively. Biological and vermicompost fertilizers not only improved the amount of EO but also enhanced its quality and aroma, as reflected in the constituents of the EO. The GI treatment and the V₅ + NPK treatment led to high amounts of K in the branches. Meanwhile, high S contents were measured in the branches in response to the V₅ and the S₂₅₀ + T treatments. These findings suggested that biofertilizers and organic fertilizers can benefit the cultivation of S. khuzistanica because, when combined together, they can enhance the percentage and phenolic compounds in the EO.