Growth, essential oil yield and components of summer savory (Satureja hortensis L.) influenced by Salicylic acid and Proline

Today, the use of essential oils of medicinal plants has become very important for human health. Proper nutrition of medicinal plants plays a critical role in the quantitative and qualitative performance of their essential oils. In order to investigate the effects of foliar application of salicylic acid and proline on the vegetative and biochemical characteristics of savory, an experiment was performed in a randomized complete block design with three replicates at the Research Farm in Islamic Azad University, Saveh branch, Iran. Treatments included salicylic acid (0.5 and 1 mM) and amino acid proline (1.5 and 3 g/L), and the control. Foliar application was done in three phases: stem elongation, flower initiation, and flowering. Plant height, number of flowers and side-stems, fresh and dry weights of leaves and shoots, and essential oil percentage and ingredients were investigated. Results indicated that the maximum number of flowers (21.66), plant height (47.26 cm), leaf dry weight (5.34 g), and leaf fresh weight (16.17 g) were observed by applying 1.5 g/L proline. The maximum shoot dry weight (8.85 g), shoot fresh weight (48.53 g), and number of side-stems were observed by applying 1 mM salicylic acid. The highest (183.65 kg/ha) and the lowest (76.92 kg/ha) essential oil yield were achieved by applying 1.5 g/L proline and control, respectively. The most typical components of essential oil were γ-terpinene and Carvacrol. In conclusion, the highest effects on essential oil yield were obtained under the foliar application of 1 mM salicylic acid and 1.5 g/L proline.