Effect of plant density on quality and quantity yield of Thymus kotschyanus Boiss. in dry farming condition from five provinces of Iran

In order to find the plant density effects on quality and quantity yield of Thymus under dry farming conditions, a field experiment was performed in a randomized block design with three replications in five different dry farming regions of the country during 2 years. The experimental treatments were including plant density (4, 6 and 8 plant/m2), year (1 and 2 years after planting) and location (Azerbaijan e Sharghi, Kourdestan, Kermanshah, Guilan and Tehran). The measured traits comprised of plant height, canopy diameter, dry matter of aerial parts, essential oil yield and content, which were assessed during full flowering time. Analysis of variance of density, location and year showed significant main effects and interactions on all studied traits. Based on the results of density × location, the highest (1289 kg/h) dry matter yield was achieved in the samples of Tehran location at 8 plant/m2 density. The highest essential oil content (2.31%) was obtained in samples from Kurdistan at 6 plant/m2 density, although there was no significant difference between 6 and 4 plant/m2 density. The highest essential oil yield, 24.53, 24.76 and 23.87 kg/h, were obtained in Damavand, Guilan and Kermanshah at 8 plant/m2 density, respectively. The yield of dry matter and essential oil of aerial parts of Thymus in the second year were more that those of the first year, also, the content of essential oil in the second year were increased 30%. Enhancement of quality and quantity values of traits in the second year show high adaptation of this valuable specie under different dry farming conditions of the country, and Guilan, Tehran and Kurdistan could be introduced as prone regions for cultivation of this highly valuable medicinal plant.