Changes in essential oil content of different organs of dill genotypes in response to water deficit

A split plot experiment (based on RCB design) with four replications was conducted in 2014, to evaluate the effects of different irrigation treatments (I1, I2, I3 and I4: irrigation after 70, 100, 130 and 160 mm evaporation, respectively) on essential oil content of dill (Anethum graveolens L.) organs in two genotypes (Local and Mammoth). Irrigation treatments and genotypes were allocated to the main and sub-plots, respectively. Essential oil percentage of dill organs increased, but their essence yield decreased as water deficit severed. Mammoth had the highest essential oil percentage in all organs, but essential oil yield of vegetative organs and flowers of the local genotype was much more than that of mammoth genotype. However, the difference in essence yield of seeds between two genotypes was not significant. The highest essential oil percentage and yield under all irrigation intervals were obtained from seeds, followed by flowers and vegetative organs. It was concluded that seeds and flowers are the most beneficial organs of dill, regarding essential oil production, although dill is largely used as a vegetable.