Effect of Sowing Date and Nitrogen Rate on Morphological Traits, Seed Production and Essential Oil of Pulicaria gnaphalodes (Vent.) Boiss.

Pulicaria gnaphalodes (Vent.) Boiss. is a medicinal plant perennial and herbaceous belong to Asteraceae family which grows in some parts of Iran. In order to investigate the effect of two sowing dates (May ۳ and ۲۳) and nitrogen rates (۰, ۸۰, ۱۶۰, and ۲۴۰ kg N/ha) on morphological traits, yield and yield components and essential oil yield of P. gnaphalodes aerial parts, a factorial experiment based on a randomized complete block design with three replications was carried out in research field of Birjand branch, Islamic Azad University, Birjand, Iran in ۲۰۱۸. The results of analysis of variance showed that the simple and interaction effects of sowing date and nitrogen rate significantly affected plant height, number of main branch, number of capitols per plant, seed yield, dry weight and percentage of essential oil produced by the aerial parts at ۱% level. In addition, the number of secondary branches, canopy diameter, number of seed per capitols and ۱۰۰۰-seed weight were affected by the nitrogen content at ۱% level. The effect of sowing date on the number of main branches and canopy diameter was significant at the ۱% level and on ۱۰۰۰-seed weight was significant at ۵% level. Means comparison of simple effect of sowing date showed that plant height, number of main branches per plant, number of secondary branches per plant, canopy diameter, number of capitols per plant, ۱۰۰۰-seed weight, seed yield, and dry weight of the aerial parts had a significant superiority in the sowing date of May ۳ compared to May ۲۳, by ۱۵.۷, ۱۹, ۱۲.۱, ۱۰, ۵۱.۴, ۱۵.۸, ۸۸.۳ and ۳۳.۱%, respectively. Increasing the application of nitrogen to ۲۴۰ kg N/ha also significantly increased the mentioned traits by ۲۴, ۴۱.۲, ۱۷.۶, ۲۹.۳, ۸۲.۶, ۱۱۵.۳, ۳۶.۲, and ۱۸۷.۳%, respectively compared to ۰ kg N/ ha (control). Means comparison of interaction effect between sowing date and nitrogen rate showed that the maximum plant height (۶۸.۵۰ cm), number of main branches per plant (۱۷ branches per plant), number of capitols per plant (۱۷۰), seed yield (۳۲۲.۸۷ kg/ha) and dry weight of the aerial parts (۱۸۰۸.۵۲ kg/ha) were obtained in the treatment of the sowing date of May ۳ with application of ۲۴۰ kg N/ha.

Keywords:

essential oil , Fertilizer , medicinal plant , Planting date , yield