Effect of foliar application of zinc and Humic acid on the growth physiology and the essential oil component of Melissa officinalis

The medicinal plants are full of secondary metabolites which are the main source of active substances in plenty of drugs. Essential oils are one of the most important ingredients in medicinal plants. Although effective materials are essentially made by guiding genetic processes, their producing significantly influenced by environmental factors. In order to study the effect of foliar application of zinc sulfate and humic acid on the growth physiology and the quality of essential oil of Melissa officinalis, an experiment was carried out in a randomized complete blocks design with 3 replications in the research farm of Islamic Azad University Saveh branch. The first factor was zinc sulfate at three levels: 0, 0.5 and 1 g / litter and the second factor was the humic acid content of three levels: 0, 3 and 5 g / litter. The data obtained from the analysis of variance showed that Zn sulfate on shoot length and number of branches at 5% probability level and on leaf length, leaf width, shoot weight and dry weight, dry matter, essential oil percentage, essential oil yield Essential components have a significant effect on the level of 1% probability but it didnt have a significant effect on the leaf length and leaf width. Also, the interaction of zinc sulfate with humic acid had significant effect on shoot fresh and dry weight, dry matter, essential oil yield, Linanol percentage at 1% probability level and essential oil percentage at 5% probability level But it did not significantly affect on shoots length, number of shoots, leaf length and width and citronella and citral percentage. Based on the results, the highest traits were measured in a treatment of 0.5 g / L zinc sulfate and 5 g / L humic acid.