Effects of Drought Stress on Growth and Physiological Characteristics of Dill (Anethum graveolens L.)

In order to study the effect of different water potential on Anethum graveolens L. an experiment was conducted. This study was carried out based on completely randomized design with three replications. In this experiment، morpho-physiological characteristics were assessed under hydroponic. Stress was established with PEG 6000، and drought potentials were: 0 (control)، -1. 5، -2، -2. 5 and -3 bar. The results showed that effect of drought stress on morphological characteristics including: shoot length، root length، surface of leaves and leaves number was significant (p≤0. 01). Mean comparison of treatments showed that with increasing drought stress، all parameters decreased. Effect of drought stress on amount of a، b and total chlorophyll، carotenoid، soluble proteins، phenolic compounds and K+، P and Ca+2 concentrations in shoot and root were significant (p≤0. 01). Effect of drought stress on chlorophyll a/b ratio was significant (p≤0. 05). Mean comparison of treatments showed that with increasing drought stress، amount of chlorophyll، carotenoid، soluble proteins، K+، P and Ca+2 and shoot/root K+ ratio decreased where as amount of phenolic compounds in shoot and root increased. Shoot to root length ratio and shoot/root K+ ratio were not influenced by drought stress (p≤0. 05). From the results of this study، it can be deducted that dill medicinal plant respond to drought stress by increasing of phenolic compounds.