TIME-BASED CHANGES IN ESSENTIAL OIL CONTENTS AND COMPONENTS OF ENGLISH LAVENDER (Lavandula angustifolia MILL.) AFTER FOLIAR APPLICATION OF GIBBERELLIC ACID (GA3)

Abstract

Lavender ( Lavandula angustifolia Mill. family Lamiaceae) is a perennial and highly drought tolerant plant species. It grows well on calcareous slopes, and produces a fragrant essential oil. The aim of study was to evaluate foliar application of gibberellic acid (GA 3 ) and delaying harvesting for different durations on essential oil and components of English lavender after foliar treatment with 0, 200, 400 and 600 mg l -1 gibberellic acid (GA 3 ). Clevenger apparatus-based water-vapor distillation method was used to determine essential oil and its components by GC-MS. The experiment was established in split plots in randomized complete block design with two factors and 3 replications. The main plots were formed at harvest time and the sub-plots were created by GA 3 applications. Statistical analyzes were made using MSTAT-C package program. When the GA 3 doses and harvest times interaction were evaluated together, the average essential oil yield of the harvested lavender flowers ranged 6.20 to 8.20 % showing the prominent influence of the concentration of GA 3 and delay in harvesting (in hours) on concentrartration of alkaloids. More than 50 components were identified, the most important among these was 1.8-cineole, linalool, camphor, borneol, lavandulol, and terpinene-4-ol. The amount of linalool, which improves the quality of the essential oil ranged 34.49-38.75%. The minimum and the maximum essential oil values were noted from the flowers harvested after 30 hours (control treatments), and 54 hours from 400 mg l-1 GA 3 treated plants in the same order. However, essential oil contents showed a slight decrease at higher GA 3 treatments and prolonging duration of harvest after respective GA 3 treatments. GA 3 treatments enhanced the quantity of essential oil substantially, and the optimal dose was determined as 400 mg l -1 GA 3 on samples harvested after 54 hours following application. The results further showed that the quantities of essential oil's primary components varied according to harvest time.