Improving essential oil content and yield of ajowan organs under water stress by application of salicylic acid and abscisic acid

This research was carried out in 2014 and 2015 to assess the effects of salicylic acid (SA)(0 and 1 mM) and abscisic acid (ABA) (0 and 50 µM) on essential oil content and yield ofajowan (Carum copticum L.) organs under different irrigation intervals (I1, I2, I3, I4: irrigationafter 70, 100, 130 and 160 mm evaporation, respectively). Plants were sprayed by SA and ABAat vegetative and reproductive stages. In both years, the biomass of vegetative organs (leavesand stem), flower production and seed yield per unit area of ajowan decreased with decreasingwater availability. All organs mass improved by application of ABA and particularly SA.Essential oil percentage of all organs increased, but essence yield decreased as a result of waterlimitation. Reduction in essential oil yield of ajowan organs due to water stress strongly relatedwith the reduction of individual organ mass under stress. Foliar spray of ABA and especiallySA improved the medicinal and commercial value of ajowan under different irrigation intervalsby enhancing plant organs biomass and accumulation of more essential oil.