Effect of Biological Nitrogen on the Yield of Dried Flower and Essential Oil of Calendula officinalis L. under End Season Water Deficit Condition

ABSTRACT: To evaluate effect of irrigation disruption on the essential oil content, and yield of dried flower and essential oil of Calendula officinalis L., an experiment was conducted as split plot at the Research Farm of Faculty of Agriculture, Urmia University (latitude 37.53 °N, 45.08 °E, and 1320 m above sea level) in 2010. Treatments; irrigation (irrigation disruption at first, second, third harvest and without disruption as control) as main plot and amount of biological nitrogen (0, 3, 6, and 9 (Liter per hectare) of biological nitrogen included Azotobacter and Azospirillum sp.) as sub plot were arranged in randomized complete block design with three replications. Data analysis of variance showed the significant interaction effect between irrigation disruption and biological nitrogen on essential oil content, flower yield and essential oil yield in first harvest, second harvest, third harvest, fourth harvest, fifth harvest and yearly total yield. The maximum yearly total yield of flower (2742.91 kg/ha) was obtained from control treatment of irrigation (without irrigation disruption) and 6 l/ha of biological nitrogen. The highest yearly total yield of essential oil (23.95 kg/ha) and the highest percentage of essential oil (1.03 %) belonged to irrigation disruption after first harvest and 9 l/ha of biological nitrogen. In general, biological nitrogen caused in the higher yield of Calendula officinalis in different amounts for production of dried flower and essential oil compared with control treatment.