The effect of sowing date and planting density on the essential oil content and composition of Valeriana officinalis L

In order to investigate the effect of sowing date and planting density on the essential oil content and composition of valerian, this experiment was conducted in the years of 2005-2006 at Experimental Farm in Abureyhan Campus, University of Tehran. This experiment performed in split plot form based on a complete randomized block design with four replications. The main factor was the sowing date with three levels (11th August, 1st and 22nd September), sub factor was the density with three levels (40000, 80000 and 120000 plants/ hectare). Seeds of valerian provided by research department on medicinal plants in University of Shahid Beheshti. After isolating essential oil from dried roots by the hydrodistillation method, composition of essential oil were identified by gas chromatography (GC) and GC/Mass spectrometry analysis. Number of 87 composition were identified in essential oil. Bornyl acetate, valerenal, camphene and valeranone were the highest percentage in other compositions of essential oil. According to the results, sowing date and planting density had significant effect on essential oil percentage and its composition (bornyl acetate, valerenal, camphene and valeranone) (P≤0.01). Interaction of sowing date and planting density had significant effect only on essential oil percentage (P≤0.05). Final results showed that the highest amount of essential oil percentage and its composition (bornyl acetate, valerenal, camphene, and valeranone) was obtained on 22nd September and 40000 plants per hectare.