Effect of ethanol and humic acid foliar spraying on morphological traits, photosynthetic pigments and quality and quantity of essential oil content of Dracocephalum moldavica L.

In order to study the effects of humic acid foliar spraying on morphological traits, photosynthetic pigmentation, and essential oil content of Dracocephalum moldavica, a factorial experiment was conducted based on a randomized complete block design with three replications in Saveh. The investigated factors included the use of humic acid at four levels 0 (control), 200, 400, and 800 mg/L and ethanol at four levels of 0 (control), 5, 10, and 15%. The measured traits were biological yield, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, essential oil percentage, and essential oil yield. Results showed that humic acid increased biological yield, chlorophyll a, chlorophyll b and total chlorophyll, essential oil percentage, essential oil yield, carotenoid, and free sugar. The highest positive effect was observed in 400 mg/L humic treatment. Ethanol increased biological yield, chlorophyll a, chlorophyll b and total chlorophyll, essential oil content, essential oil yield, carotenoid, and free sugar. In general, the highest positive effect was obtained in 10% ethanol treatment. Results showed that the use of humic acid with ethanol, especially in the combination of 400 mg/L humic acid with 10% ethanol, improved morphological characteristics, photosynthetic pigments, and yield of essential oil of Dracocephalum moldavica.