change in essential oil percent and yield of lavender (lavandula angustifolia l.) under drought stress and pgpr application methods conditions

in order to study the effects of pgpr application methods on essential oil percent and yield of lavender (lavandula angustifolia l.) under drought stress conditions an experiment was performed at islamic azad university, yadegar-e-imam khomeini (rah) shahre-rey branch. this experiment was carried out in a split plot arrangement with randomized complete block design in three replications. experimental factors were included irrigation regimes as the main plot in three levels including 60, 110 and 160 mm evaporation from a class pan, and pgpr application methods in four levels including, non application, root inoculation, application in irrigation water, and root inoculation+irrigation in irrigation water methods as the subplot. the results indicated that, simple effect of irrigation and pgprs were significant on experimented traits but the interaction effects was significant on essential oil yield only. in this case, drought stress increased essential oil percent in lavender. so the highest amount of mentioned traits observed in irrigation at 160 mm and the lowest one obtained at 60 mm irrigation management. based on findings, drought stress decreased the essential oil yield. therefore the highest essence yield conducted at 60 mm and the lowest one gained at 160 mm irrigation regime  management according to class a evaporation pan.