Foliar application effects of salicylic acid and indole acetic acid on the essential oil composition of Mentha piperita L. and Melissa officinalis L.

Growth regulators play a crucial role during plant growth and development and utilizing of them can a possible approach to improving plants economic yield. In this research, the effects of two elicitors [salicylic acid (SA) and indole acetic acid (IAA)] on the accumulation of essential oils in the shoot cultures of Mentha piperita L. and Melissa officinalis L. were studied. This research was conducted in pot expriment in randomized complete design in factoriel layout with 4 repeatitions in 2016. The following treatments were applied after the plants had 6 and 8 leaves: IAA (0, 1, 1.5, 2 mg/l), SA (0, 1, 10, 20 mM). Harvesting was done in 3 weeks after of second foliar application in time of plants had 16-22 leaves. Twenty-eight (28) essential oils in Mentha piperita L. were obtained and the most notable (more than 70%) were: menthol, menton and izomenton. Twenty-three (23) essential oils in Melissa officinalis L. were obtained and the greatest notable (more than 65%) were: geranial, neral and menthol and in Mentha piperita L. Results indicated mixed treatment of salicylic acid (10 mM) and indol acetic acid (1.5 mg/l) was the best treat on essential oil content and composition. It seems that the positive effects of hormones increased yield and then increased essential oil content and composition.