effects of drought stress and salicylic acid on morphological and physiological traits of (foeniculum vulgare mill.)

recently, 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 research farm of shahid bahonar university of kerman in 2012. three levels of drought stress (50, 75 and 100% of field capacity) and 3 concentrations of sa (0, 0.5 and 1mm) were considered as main and sub plot respectively. foliar application of sa was performed at 3 to 4 leaf growth stage and before application of drought stress. the results showed that drought stress reduced plant height, the number and length of internodes on the main stem , grain yield and leaf protein (14.2, 2.4, 31.5, 51 and 23.5 percent respectively) and increased lipid peroxidation, hydrogen peroxide and phenolic compounds(66.6, 10.5 and 14.1 percent) compared to control. with increasing concentrations of salicylic acid, except for a reduction in lipid peroxidation and hydrogen peroxide (31.8 and 13.7 percent) a significant increase was observed in other traits when compared to control. interaction of drought stress and sa on internode length on the main stem, lipid peroxidation and protein were signified. it was concluded that salicylic acid whit concentration of 1 mm has an effective role in alevieting stress injuries induced by drought.