| Abstrakt: |
Thyme essential oil is important due to its use in the pharmaceutical, food and cosmetic industries. Many factors including nutrition, harvest time and environmental conditions can influence thyme quality and yield. To investigate the effect of nitrogen levels and harvest time on the quality and yield and chemical composition of thyme essential oil, a factorial experiment was conducted based on RCBD with three replications at Razi University in three consecutive years of 2018- 2020. The first factor included amount of nitrogen fertilizer (0, 50 and 100 kg N ha-1 ) and the second factor included the time of harvest (late Jun. and Sep. during flowering). The results showed that the quality and yield as well as chemical composition of essential oil were affected by nitrogen, cutting and year. Nitrogen increased several characteristics, including plant height, number of lateral branches, leaf, stem and total dry weights, stem diameter, percentage and yield of essential oil (p≤0.01). Also, the amount of these traits in the second cutting was higher than the first cutting. The highest value of all investigated traits was obtained in the interaction treatment of second cutting×100 kg N ha-1 ×the third year. The most chemical compounds of the essential oil include thymol (41-61.25%), γ-terpinene (11.10 - 23.60%), p-cymen (10.63-23.07%), carvacrol (3.40-4.63%), α-terpinene (1.42-3.06%), and α-Phellandrene (1.02-1.97%) respectively. Nitrogen increased all the chemical compounds of the essential oil. The concentration of carvacrol, α-terpinen and γ-terpinene, p-cymene and α-Phellandrene decreased with increasing nitrogen from 50 to 100 kg ha-1. Overall, the application of nitrogen in the second cutting had a significant effect on increasing the yield and quality of thyme. Also, the percentage of chemical compounds in thyme essential oil changed according to the level of nitrogen consumption and harvest time during the three years of the experiment. [ABSTRACT FROM AUTHOR] |
