Effect of irrigation time and nitrogen fertilizer on growth period and chamazulene content of German chamomile (Matricaria chamomilla L.) in cold and semi-arid region

In order to study the effects of irrigation time and nitrogen fertilizer on growth period, essential oil and chamazulene yield of German chamomile (Matricaria chamomilla L.), Bodegold variety, an experiment was conducted in a cold and semi-arid region, Tabriz, Iran, as split factorial with irrigation times (after 60, 120, 180 mm evaporation from pan), urea rates (50, 100, 150 kg ha-1, equivalent with 23, 46 and 69 kg ha-1 pure nitrogen) and urea splitting (100% in planting time, equally in planting and stem elongation stages, 25%:50%: 25% in planting, stem elongation and early flowering stages). Analysis of flower essential oil was done by GC/MS. Results showed that emergence of flower bud in treatments irrigated after 180 and 60 mm evaporation from pan, happened after 70 and 78 days respectively. Increasing of urea application delayed full flowering of chamomile. Delay in irrigation from 60 to 120 mm evaporation reduced dry flower yield up to 2.3%. Application of nitrogen fertilizer at two stages of planting and stem elongation increased flower yield up to 351 kg ha-1. Shoot dry weight of chamomile increased from 76 g m-2 in the third level of irrigation to 126 g m-2 in average of first and second levels of irrigation. The highest essential oil yield (2.82 l ha-1) was obtained when urea was equally applied at planting and stem elongation stages. After applying 50, 100 and 150 kg ha-1 urea, chamazulene content was respectively calculated as 0.31, 0.44 and 0.36 l ha-1. According to the results, for chamomile cultivation in this region and also other similar areas it is recommended that irrigation is done after 120 mm evaporation from pan and 46 kg ha-1 nitrogen is equally applied at planting and stem elongation stages.