effects of vermicompst and nitroxin biofertilizer on quantity and quality of essential oil of dragonhead (dracocephalum moldavica l.)

introduction dragonhead (dracocephalum moldavica l.) is an annual herbaceous aromatic plant and belongs to lamiaceae family. it is native to south of siberia and himalayan hillsides. the essential oil content shows great variation due to plant origin. the main constituents of dragonhead essential oil have been reported as geranial, geranyl acetate, neral and geraniol. using organic manures and biofertilizers such as vermicompost and nitrogen fixing bacteria contain azotobacter and azospirillum has led to a decrease in the application of chemical fertilizers and has provided high quality agricultural products. several studies have shown that organic and bio-fertilizers application such as vermicompost and nitroxin can increase quantity and quality of essential oil of medicinal plants of dragonhead, anise and thyme (darzi et al., 2013; mafakheri et al., 2012; mohammadpour vashvaei et al., 2015). therefore, the main objective of the present field experiment was to investigate the effects of vermicompst and nitroxin biofertilizer on quantity and quality of essential oil of dragonhead. materials and methods an experiment was conducted as afactorial experiment in the base of randomized complete blocks design with six treatments and three replications at research field of agriculture company of ran in firouzkuh of iran in 2013. the factors were vermicompost in three levels (0, 5 and 10 t.ha-1) and nitroxinbiofertilizer (inoculated seeds and non-inoculated). inoculation was carried out by immersing the dragonhead seeds in the cells suspension of 108 cfu/ml for 15 min. the required quantities of vermicompost were applied and incorporated to the top 5 cm layer of soil in the experimental beds before planting of dragonhead seeds. each experimental plot was 3 m long and 2.28 m wide with the spacing of 10 cm between the plants and 38 cm between the rows. there was a space of one meter between the plots and 2 meters between replications. in this study, quantitative and qualitative traits of dragonhead essential oil content, granial percent, granyl acetate percent, neral percent, graniol percent and neryl acetate percent in essential oil were evaluated. for determine the essential oil content (%), about 100 g dried herb of dragonhead (dried in shadow) as sample from the each plot were selected and then were subjected to hydro-distillation (clevenger type apparatus) for 2 till 3 hours. for identifying the essential oil components, essential oil fraction was collected and subjected to gc and gc/ms (gas chromatography and gas chromatography-mass spectrometry) analysis. analysis of variance by using sas software and mean comparisons by duncan’s multiple range test (at the 5% probability level) was done. results and discussion the present resultsshow that the highest essential oil content in applying 5 t.ha-1 vermicompost and the maximum geranyl acetate in essential oil in applying 10 t.ha-1 vermicompost were obtained. nitroxin biofertilizer showed significant effects on geranyl acetate in essential oil only, as the highest geranyl acetate were obtained by using the nitroxin (inoculated seeds). also, the intractions effect of factors on essential oil content, geranyl acetate, graniol and neryl acetate in essential oil were significant, as the highest essential oil content and neryl acetate percent at treatment of 5 t.ha-1 vermicompost and without application of nitroxin and the maximum geranyl acetate and the lowest geraniol in essential oil at treatment of 10 t.ha-1 vermicompost and application of nitroxin were obtained. according to the results of this study, the maximum essential oil quantity at treatment of 5 t.ha-1 vermicompost and without application of nitroxin and the highest essential oil quality at treatment of 10 t.ha-1 vermicompost and application of nitroxin were obtained. conclusion vermicompost application positively influenced on quantity and quality of essential oil dragonhead, as the highest essential oil content in treatment of application of 5 t.ha-1 vermicompost and the highest essential oil quality in treatment of integrated application of 10 t.ha-1 vermicompost and nitroxin were obtained. on the base of research results, organic and bio-fertilizers application such as vermicompost and nitroxin in a sustainable agriculture system can be caused in improvement of qualitative characters of dragonhead.