Growth and quality of lemon balm (Melissa officinalis) as influenced by various plant extracts

Abstract: Lemon balm (Melissa officinals) is one of the most valuable medicinal plants in herbal medicine. Bio-stimulants are likely to gain popularity as an alternative strategy for providing plants with nutrients, vitamins, and hormones that increase yield and quality. Field trials were conducted during two successive seasons, 2017/2018 and 2018/2019, to assess lemon balm's growth and essential oil response to natural plant extracts with various concentrations. Lemon balm plants were exposed to moringa leaf extract (1, 2, 3 %), pomegranate peel extract (0.5, 1, 1.5 %) and banana peel extract (1, 2, 3 %) as a foliar spray. Growth characters (plant height, fresh and dry weights /plant) and chemical contents (NPK and total carbohydrates) were recorded. Moringa extract at 3% surpassed, in most cases, other plant extracts in improving the vegetative growth traits of lemon balm. Banana peel extract was more effective in increasing oil percent than moringa or pomegranate extracts. Besides, all extracts caused increase in N,P,K and carbohydrates over control while they yielded volatile oil without significantly altering the quality.