Effect of Drought Stress on Some Morphological Characteristics, Quantity and Quality Essential oil in (Rosmarinus officinalis L.)

Abstract

In order to investigate the effect of different levels of drought stress on plant growth and essential oil composition of Rosemary aerial parts, a completely randomized design (CRD) with five treatments and three replications was conducted in the University of Kashan in 2017. The water stress treatments contained: 100, 85, 70, 55 and 40% of field capacity (FC). The results of statistical analysis showed that the water stress had significant effects on morphological characteristics and percentage and essential oil composition. By decreasing the amount of soil water, length, fresh weight of stem and fresh and dry weight of root reduced. Also, the percentage of essential oils first increased and then decreased. Decreasing of growth parameters was observed in the fifth level of stress (40% of FC) and plants produced very little flowers. In order to investigate the essential oil factors, the aerial parts were separated and their essential oils were extracted, more essential oil was obtained in 85% FC condition. The important compound in the essential oils was Camphor which increased its value with increased level of drought stress. Also, Camphene, that has reduced the quality of the essential oil, first decreased by increasing the drought stress level and then increased. Therefore it can be concluded that in the initial levels of drought stress (85% FC) the percentage of essential oil increased but with increasing drought stress (55% FC), despite the decrease in the percentage of essential oil produced, its quality increased. So, the best stress level for increasing the essential oil production was 85% FC, and for the essential oil quality was 55% FC.