Chemical composition and yield of essential oil from lemon balm (Melissa officinalis L.) under foliar applications of jasmonic and salicylic acids

Abstract

Abstract Jasmonic acid (JA) is regarded as endogenous regulator that plays important roles in regulating stress responses, plant growth, and development. Salicylic acid (SA) has been identified as an important signaling element involved in establishing the local and systemic disease resistance response of plants after pathogen attack. A field experiment was conducted to assess the foliar applications effect of JA and SA on quantity and quality yields of essential oil of lemon balm (Melissa officinalis L.). Experimental treatments were: I) water foliar application; II) water + 1% ethanol foliar application (as a solvent); III-V) JA at 0.05–0.40 mg L−1; VI-IX) SA at 0.14–14.00 g L−1. The essential oil contents of the treatments ranged between 0.55 to 0.61% (v/w). The results of analysis of the essential oils by GC-FID and GC/MS indicated that monoterpene oxygenated and sesquiterpenes were the major components. There were no significant differences among treatments for essential oil content, dry matter weight, and some of volatile components (neral and geranial). The foliar spray JA significantly improved the amounts of two phenolic monoterpenes compounds such as thymol from 0.42% in control to 4.37% in JA at 0.40 mg L−1 and carvacrol from 0.77% in control to 14.76% in JA at 0.40 mg L−1. In addition, the highest percentages of β-caryophyllene and caryophyllene oxide were obtained from the foliar application of SA and JA. In conclusion, the exogenous application of JA and SA can considerably improve some secondary metabolites especially monoterpene oxygenated and sesquiterpenes in lemon balm plants under filed conditions.