Effects of salicylic acid on some physiological traits, yield and yield components of fennel (Foeniculum vulgare Mill.) under drought stress

Recently, the application of SA has increased to improve plants’ resistance to stresses such as drought. Hence to investigate SA effects on morphophysiological characteristics of Fennel (Foeniculum vulgare Mill.) under drought stress, a split plot experiment based on latin square design with three replications was carried out at the research farm of Shahid Bahonar University of Kerman in 2012. Three levels of drought stress (50, 75 and 100% of field capacity) and three concentrations of SA (0, 0.5 and 1mM) were considered as main and sub-plot treatments, respectively. Foliar application of SA was performed at 3-to 4-leaf growth stage and before application of drought stress. Results showed that the drought stress reduced the number of fertile umbel/plant, the number of fertile umbellate/umbel, the number of grains/umbellate, relative water content, chlorophyll, carotenoids and grain yield, while increased electrolyte leakage when compared with control. Salicylic acid reduced electrolyte leakage, while increased the number of fertile umbel/plant, the number of fertile umbellate/umbel, the number of grains/umbellate, RWC, chlorophyll, carotenoids and grain yield when compared to control (No SA application). Interaction of drought stress × SA on the number of fertile umbel/plant, the number of fertile umbellate/umbel, RWC, carotenoids and grain yield was significant. Increasing photosynthetic pigments, RWC and decreasing electrolyte leakage indicates a reduction in oxidative damage and implies SA role in tolerance of fennel to drought stress.