Effect of Different Irrigation Levels on Morphological, Physiological and Antioxidative Characteristics of Isatis cappadocica Desv

Woad (Isatis cappadocica Desv.) is a herbal plant, native to central and western Asia and from Brassicaceae family. In this research, we have investigated the effects of different irrigation levels on plant morphological and physiological attributes including canopy area, roots and shoots dry and fresh weight, roots length, proline concentration, shoots soluble carbohydrates content and antioxidant enzymes activity in a 4-replicate completely randomized design pot experiment. Irrigation regims consisted of replenishment of 100, 75 and 50 percent of soil water depletion (I100, I75 and I50) from the root zone. Results showed that drought stress had not significantly affected plants canopy area. The lowest and highest shoots fresh and dry weights were recorded in treatments I100 and I75-50, respectively. Roots fresh and dry weight and proline concentration were greater in I50 than the remaining irrigation levels. The shoot soluble carbohydrates content and root length were greatest in I50 level followed by I75 and I100. Also, there was an increasing trend in antioxidant enzymes activity from the second to fourth week after the commence of irrigation treatment. In I50, activity of ascorbat peroxidase, peroxidase and catalase enzymes were greater than the other irrigation levels. Superoxide dismutase was found to indicate greatest activities at the presence of I50 and I75 levels of irrigation.