Effect of organic fertilizers and Salicylic acid on the yield and some secondary metabolites of Lemon balm (Melissa officinalis L.)

In this research, the effects of organic fertilizers (Bovine, Sheep, Leaf mould and Vermicompost fertilizers) combined with foliar application of salicylic acid (SA) at the rate of 0, 10-2, 10-4 and 10-6 M on essential oil percentage and some secondary metabolites of Lemon balm were investigated. The experiment was conducted as complete randomized block design with factorial arrangement in pots with three replications. The parameters such as shoot fresh & dry weights, oil percentage, essential oil components, the amount of RA and the antioxidant activity were measured. Essential oil was extracted by Clevenger, the essential oil components were identified by GC/MS, RA was estimated by HPLC and antioxidant activity was measured by spectrophotometer. Based on the analysis of variance, the effects of organic fertilizers and SA on oil percentage, the amount of RA and antioxidant activity were found to be significantly different. Maximum oil percentage (%0.536) was recorded in the treatment of bovine fertilizer combined with 10-2 M SA and the lowest level (%0.203) was observed in bovine and sheep fertilizers without SA. The essential oil analysis revealed that Citral (E & Z) at the rate of 61.88 % was the highest essential oil component of lemon balm. The highest and lowest amounts of RA were found in plants treated with Sheep manure 10-4 M SA and control plants respectively.