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

Abstract

<span class="fontstyle0">This research was carried out in 2014 and 2015 to assess the effects of salicylic acid (SA)<br />(0 and 1 mM) and abscisic acid (ABA) (0 and 50 µM) on essential oil content and yield of<br />ajowan (</span><span class="fontstyle2">Carum copticum </span><span class="fontstyle0">L.) organs under different irrigation intervals (I</span><span class="fontstyle0">1</span><span class="fontstyle0">, I</span><span class="fontstyle0">2</span><span class="fontstyle0">, I</span><span class="fontstyle0">3</span><span class="fontstyle0">, I</span><span class="fontstyle0">4</span><span class="fontstyle0">: irrigation<br />after 70, 100, 130 and 160 mm evaporation, respectively). Plants were sprayed by SA and ABA<br />at vegetative and reproductive stages. In both years, the biomass of vegetative organs (leaves<br />and stem), flower production and seed yield per unit area of ajowan decreased with decreasing<br />water availability. All organs mass improved by application of ABA and particularly SA.<br />Essential oil percentage of all organs increased, but essence yield decreased as a result of water<br />limitation. Reduction in essential oil yield of ajowan organs due to water stress strongly related<br />with the reduction of individual organ mass under stress. Foliar spray of ABA and especially<br />SA improved the medicinal and commercial value of ajowan under different irrigation intervals<br />by enhancing plant organs biomass and accumulation of more essential oil.</span>