Plant density and manure application affected yield and essential oil composition of Bakhtiari savory (Satureja bachtiarica Bunge.)

The use of soil amendments and cultivated techniques are effective strategies in improving plant yield. Bakhtiari savory (Satureja bachtiarica Bunge.) is an endemic medicinal plant of Iran with various medicinal purposes. To observe the effect of cattle manure (30 t ha(-1)) and plant density (high plant density, HPD: 80,000; medium plant density, MPD: 40,000, and low plant density, LPD: 26,666 plants ha(-1)), an experiment was accomplished as split plot with three replicates during 2018 and 2019 on plant yield, nutrients concentration, essential oil (EO) yield and composition, and also stomatal properties of Bakhtiari savory in the dryland farming conditions. The maximum plant weight was observed with manure application at HPD plant density in the second year. The greatest concentrations of N, Ca, and Mg were obtained in the plans treated with manure application and HPD. The increase of plant density led to decreased EO content and increased EO yield. The highest EO yield was observed in second-year plants supplied with manure at HPD. The GC and GC/MS analysis showed that the main constitutes of Bakhtiari savory EO were p-cymene (18.6-43%), carvacrol (32.3-59.3%), gamma-terpinene (5-14.3%), thymol (0.6-17.8%), and linalool (2-4.3%), representing different concentrations under the manure and plant densities. Leaf stomatal density and length at LPD was lower compared with HPD and MPD, while increased density of EO glands was obtained at LPD. To sum up, cattle manure and HPD can result in higher plant production.