Mild Drought Improves Growth and Flower Oil Productivity of German Chamomile (Matricaria recutita L.)

This study was conducted to evaluate the effects of drought stress on growth, photosynthesis and flower oil yield of chamomile (Matricaria recutita L.) at Research Farm of Islamic Azad University, Shoshtar, Iran during winter 2010-2011. Irrigation was applied at 90 % filed capacity (FC) (control), 70 % FC (medium drought stress) and 55 % FC (severe drought stress) of soil throughout the growing season. Analyzed data indicated that water stress had significant effect on growth, photosynthesis and flower oil yield and quality of German chamomile. Severe drought caused substantial reductions in plant height, shoot and flower dry weight, oil yield, chlorophyll a contents and photosynthesis rate; whereas medium drought stress increased the oil yield. Proline, soluble carbohydrates and MDA contents of chamomile were increased under drought stress and maximum accumulation was recorded under severe drought stress. However, drought stress improved the oil contents and quality of oil compared with control. In crux, medium drought stress (irrigation at 70 % of FC) not only improved growth but also enhanced the oil productivity, while severe water stress (55 % FC) decreased chamomile growth, photosynthesis rate and essential oil yield. Moreover, under drought stress quality of chamomile oil was improved. Therefore, irrigation at 70 % FC level of soil is recommended to attain maximum productivity of better quality oil of German chamomile.