Induction of Drought Tolerance in Sweet Basil (Ocimum basilicum L) by Salicylic Acid

Drought stress is a major constraint for crop production in arid and semiarid regions, such as Iran. In thisstudy, the possibility of enhancing drought stress tolerance of sweet basil plant (Ocimum basilicum L.) byexogenous application of Salicylic acid (SA) was investigated. The layout was factorial experiment inrandomized complete block design (RCBD) with 3 levels of drought stress including stress-freeconditions, mild stress and severe stress and 3 concentrations of SA (including 0, 0.75 and 1.5 mM) asmain factors and 3 replicate. The statistical analysis showed that drought stress and application of SA hadsignificant effects on the morphological, physiological and biochemical parameters of the plant such asplant height, fresh and dry weight, relative water content (RWC), chlorophyll (Chl), proline andelectrolyte leakage (EL). Result showed that drought stress imposed negative effects on plant growth andproductivity. In drought conditions, growth parameters, Chl content, RWC reduced, but proline contentand EL increased. SA application significantly caused increasing of plant growth characters, photosyntheticpigments, RWC and proline and decreased EL. In this experiment, SA application withincreasing growth rate and changing plant physiological process decreased adverse effects of droughtstress on sweet basil plants.