Effects of water deficit and salicylic acid on essential oil and antioxidant enzymes of fennel (Foeniculum vulgare Mill.)

To investigate SA effects on physiological and biochemical characteristics of fennel (Foeniculum vulgare Mill) under water deficit, a split plot experiment based on latin square design with three replications was carried out at research farm of Shahid Bahonar University of Kerman in 2012. Three levels of water deficit (50, 75 and 100 percent of field capacity) and 3 concentrations of SA (0, 0.5 and 1mM) were considered as main and sub plots, respectively. Foliar application of SA was performed at 3 to 4 leaves growth stages and before application of Irrigation. The obtained results showed that water deficit reduced grain yield, essential oil content and percentage while the amount of superoxide dismutase and guaiacol peroxidase increased significantly compared to control. Increasing in concentration of salicylic acid led to a significant increase in grain yield, essential oil content, essential oil yield, superoxide dismutase and guaiacol peroxidase compared to control. Interaction of water deficit and SA on grain yield, essential oil yield and antioxidant enzymes were significant. Increasing in antioxidant enzymes indicates reduction in oxidative damage and implies SA roles in tolerance of fennel under water deficit.