The effects of sowing date and planting density on some of the growth characteristics of Valerian (Valeriana officinalis L.) and didrovaltrate content

In order to investigate the effects of sowing date and planting density on some of the growth characteristics of Valerian (Valeriana officinalis L.) and didrovaltrate content, an experiment was conducted from 2005-2006 at Experimental Farm in Abureyhan Campus, University of Tehran. The 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 (11 August, 1 and 22 September) and sub factor was plant density with three levels (40000, 80000 and 120000 plants/ hectare). Seeds of valerian provided from Medicinal Plants Research Division of Shahid Beheshti University. Didrovaltrate amount was measured by High Performance Liquid Chromatography (HPLC). The results showed that sowing date and planting density had significant effect on root and rhizome length and diameter and percentage of didrovaltrate. The interaction effects of sowing date and planting density had significant difference on percentage of didrovaltrate, but no significant effect on other characters was seen. The highest root and rhizome length was obtained from sowing date of 11th August and 120000 plants per hectare and the highest diameter of root and rhizome were obtained from the combination of 11th August and 40000 plants per hectare. The results showed that maximum amount of didrovaltrate was obtained from the combination of 22nd September and 40000 plants per hectare.