Effects of different planting densities and feeding with organic fertilizers on percentage, yield, and essential oil chemical composition in Satureja mutica Fisch. & C. A. Mey. under rainfed conditions

Satureja mutica Fisch. & C. A. Mey. is one of the native savory species of Iran that has received much attention due to its high essential oil content and phenolic compound of thymol. Determination the most suitable and best planting density as well as soil fertility is very important in increasing the quantitative and qualitative yield of medicinal plants. In this study, to investigate the effects of plant density and feeding with organic fertilizers on quantitative and qualitative yield of essential oils in Satureja mutica Fisch. & C. A. Mey. under rainfed conditions, an experiment was conducted as split plots in a randomized complete block design with 3 replications in the Research and Education Center of Agriculture and Natural Resources of Kermanshah province in 3 crop years (2018-2020). The main factor included 3 fertilizer treatments and the sub-factor was 3 densities (2.66, 4, and 8 plants per square meter) in rows with a distance of 50 cm and with 3 planting distances (25, 50, and 75 cm). Plant aerial parts were harvested at full flowering stage and their essential oil (EO) was extracted by hydrodistillation method. EO yield was calculated according to the plant dry weight and its chemical compounds were identified using GC and GC/MS. The results showed that percentage and EO chemical composition did not show any difference between the years. There was a significant difference between the fertilizer treatments for the percentage and EO yield and thymol, carvacrol, and other EO chemical compounds at the level of 1%. There was a significant difference between the planting densities only for EO yield. Thymol had a positive relationship with the treatments of enriched straw and then rotten cow manure and the highest amount (53.2%) was observed in the enriched straw treatment. Carvacrol with the highest amount of 9.2%, showed a positive relationship with the rotten cow manure treatment.