Effects of Application Methods of Nitrogen Fertilizer in Semi Arid and Moderate Cool Conditions on Morphological and Composition on Thyme (Thymus vulgaris L.)

Thyme (Thymus vulgaris L.) is an important plant of family Lamiaceae and its essentialoil is famous among 10 essential oil of medicinal plant. In present study, effects of nitrogenapplication methods was evaluated at two moderate and semi arid zones for distinguishingthe best nitrogen application method in each habitat considering the growth differentiation balance (GDB) for vegetative production and secondary metabolites. The experiment wasconducted into a randomized complete blocks design with 3 replications in two regionsShahr e ray and Karadj in 2008. Treatments were included nitrogen application methods(no application as the control), 50 kg.ha-1 soil application and 50 kg.ha-1 foliar applications.Fresh samples of thyme plants were taken at two experimental farms and after drying in theshade, oil was extracted and the essence was analyzed by the GC apparatus. The results ofindependent and combined analyses showed that the foliar application of nitrogen at Karadjsignificantly increased plant height, percentage of thymol (2.74%) and thymol yield (19.5kg.ha-1), dry shade yield (2498.2 kg.ha-1) and essential oil (38.9 lit.ha-1) as well. In contrast,the highest values for dry shade (2772.7 kg.ha-1), yield essential oil (19.1 lit.ha-1), yield andpercentage of secondary metabolites i.e.)percentage of Thymol (1.2%) and thymol yield(7.72 kg.ha-1) percentage of P-cymene (0.68%) and P-cymene yield (7.62 kg.ha-1)and percentage of carvacrol (0.076%) and carvacrol yield (0.85 kg.ha-1) (measured underthe soil application of nitrogen on the experimental filed of Shahr e Ray). Thymol and Pcymenewere the representative compounds at two experimental locations. It was concludedthat better adaptation of thyme plant under the moderate cool and high altitude in Karadjrather than the semi arid condition in Shahr e Ray was due to the faster establishment and increase of the number of branches. Foliar application of nitrogen in Karadj resulted in akind of growth differential balance (GDB) and increased both vegetative production andthymol composition as the most important secondary metabolites of thyme. Declinedhumidity and warm wind, in the experimental farm of Shahr e Ray reduced nitrogenabsorption through the leaf feeding.