Effect of different levels of nitrogen and nitrate ammonium ratios on yield and essential oil content of Thyme daenensis (Thymus daenensis subsp. daenensis Celak) in saline and non-saline conditions

In order to investigate the effect of different levels of nitrogen and nitrate: ammonium ratios on yield and oil percentage of Thyme daenensis in saline and non-saline conditions, a factorial experiment was conducted in a randomized complete block design (RCBD) with 30 treatments and three replicates in perlite and sand medium. Nitrogen at three levels (5, 10 and 15 mM), nitrate: ammonium ratio at five levels (100:0, 75:25, 50:50, 25:75, 0:100) and salinity at two levels (0 and 50 mM sodium chloride) were applied. Results showed that the highest fresh and dry weight, percentage and yield of crop oil were obtained at 15 mM nitrogen and 75:25 nitrates: ammonium ratio in the non-saline conditions. In the saline condition the fresh and dry weight, percentage and yield of crop oil were reduced in all treatments and the highest yield was obtained in 15 mM nitrogen and 50:50 nitrates: ammonium ratio. Generally, it was concluded that the ratio of 75:25 nitrate: ammonium in non-saline condition and the ratio of 50:50 nitrate: ammonium in saline condition were the optimum ratios at 15 mM nitrogen level for obtaining the highest yield and oil percentages.