Effect of frequent harvest on yield and essential oil of lemon verbena grow under Egyptian conditions

Lemon verbena is considered as a new source of essential oil with relatively high yield used in perfumery with its strong citral. field experiments were performed at the experimental farm of qalyupia governate,egypt to study the effect of frequent harvesting on yield and essential oil of lemon verbena shrubs under the environmental conditions of egypt. the one harvest during october was favorable compared with 2 and 3 harvests since the highest values of the fresh and dry weight values were recorded. different frequent harvest significantly affected essential oil content (%,ml plant-1 and liter ha-1). thus the essential oil contents in general increased with 3 harvests per year compared with other harvests per year. the main components were d - limonene,1,8 cineol and citral. the highest values of major constituent were recorded under one harvest per year compared with 2 or 3 harvests per year.