Effect of Different Growing Media and Fertilizer Application on Yield and Essential Oil Composition in Rosemary (Rosmarinus Officinalis L.) Plant.

This study was conducted in a greenhouse at Salahaddin University in Erbil, the greenhouse is located at approximately with GPS reading latitude (36.17° North) and longitude (44.00° East). To evaluate the effects of different growing media and NPK fertilizer application (30:10:10) on the physical and chemical characteristics of (Rosmarinus officinalis L). Cuttings propagate rosemary. A factorial experiment was conducted, a completely randomized design with two factors: (1) fertilizer application method—foliar application, soil application, and control; and (2) growing media— peat moss, silt, and a peat-silt mixture. Each treatment was replicated three times. The results indicated that the type of growing media significantly affected physical growth parameters, including plant height, number of branches, fresh leaf weight, and dry leaf weight, with the highest recorded increases of 18.77%, 15.67%, 66.69%, and 37.18%, respectively. In contrast, nutrient application had a more pronounced effect on chemical traits. The highest values of (oil, protein, fiber, ash, and carbohydrate) content in response to application were (5.81%, 3.60%, 14.47%, 8.30%, and 5.44%), respectively, compared to (5.56%, 3.47%, 14.30%, 8.00%, and 6.79%) under different media treatments. These findings suggest that while the type of media has a stronger influence on physical plant development, fertilizer has a stronger influence on physical plant development. Overall, the findings highlight that while the choice of growing medium plays a critical role in enhancing vegetative growth, fertilizer application is more decisive in improving essential oil yield and biochemical composition. These results offer valuable insights for optimizing rosemary production under greenhouse conditions.