Changes in essential oil content and plant yield of dragonhead (Dracocephalum moldavica L.) affected by sowing date and nitrogen fertilizer in Khoy region

In order to study the effects of sowing date and nitrogen fertilizer on some quantitative and qualitative traits of dragonhead, a field study was conducted as factorial experiment in a randomized complete block design layout with three replications in Khoy, Firuraq during 2013. Factors consisted of three sowing dates (May 11, June 5 and June 21) and four levels of nitrogen (without nitrogen (control), 150, 225 and 300 Kg.ha-1). Results indicated that sowing date had significant effect on all of the studied traits (except of number of flowering branch). The maximum essential oil content (0.38 percent), essential oil yield (11.83 Kg.ha-1) and 1000 seed weight (2.09 g) were gained on June 5. The use of 150 nitrogen fertilizer per hectare increased number of flowering branch, dry matter yield and essential oil content in compare to control treatment While application of highest level of nitrogen (300 Kg ha-1) significantly decreased essential oil content as well as essential oil yield and seed yield. Application of 150 Kg nitrogen fertilizer per hectare increased essential oil yield by 80 percent in compare to control treatment and maximum essential oil yield observed at June 5. Plants grown on May 11 produced the highest seed yield (1542 Kg.ha-1). Application of 150 Kg.ha-1 nitrogen on June 5 due to optimum usage of soil humid and temperature condition besides of decrease usage of chemical fertilizer and movement towards sustainable agriculture lead to improving quantitative and qualitative yield of dragonhead in studied climatic conditions and thus, this treatment is introduced as the best treatment combination.