Cell stability is impaired during environmental stresses such as drought stress and subsequent Reactive Oxygen Species (ROS) production. Seed
antioxidant defense system controls a few levels of radicals. Ascorbate (ASC), an important antioxidant, has been known as a cellular redox system
supporter. Pimpinella anisum L. is a very aromatic and medicinal plant that has great export value. This study was designed for the evaluation of
the effect of polyethylene glycol (PEG) 6000 and its interaction with ascorbate on seed germination index in this plant. In a Petri dish study,
control and drought induced treatments were introduced to 9 levels of osmotic potentials by PEG 6000 (ψs=0.0 to -2.0 MPa) and one level of ASC
(1.4 mM), with 5 replications in the presence and absence of ASC for different stress levels. The results of this study revealed that in lower water
potentials, germination percentage was significantly reduced. Comparing the means of the stressed treatments showed that germination percentage
increased by using exogenous ASC. This increase was significant in the moderate stress levels. ASC has protective effect against drought stress.
Key words: Pimpinella anisum L., osmotic potential, PEG, exogenous ascorbate, germination.