Assessment of salicylic acid impacts on growth rate and some physiological parametersof lettuce plants under drought stress conditions

ABSTRACT: Drought stress is a major constraint for crop production in arid and semiarid regions, such as Iran.In this study, the effect of salicylic acid (SA) onlettuce (Lactuca sativa L.) plants under drought stress wasstudied. The layout was factorial experiment in randomized complete block design (RCBD) with 3 levels of drought stress including stress-free conditions, mild and severe stress and 3 concentrations of SA (0, 0.75 and 1.5 mM) as main factors and 3 replication. The experiment was conducted in the greenhouse of agricultural faculty of Ilam University. Statistical analysis showed significant effects of the drought and SA on plant growth parameters, photosynthetic pigments, leaf relative water content (RWC), electrolyte leakage (EL), prolineand malondialdehyde (MDA) content. Results showed that drought stress imposed negative effects on plant growth and productivity. In drought conditions, fresh and dry weight, leaf area, photosynthetic pigments and RWC reduced but EL, prolineand MDA increased. SA application significantly increased plant fresh and dry weight, leaf area, Carotenoids and proline and decreased MDA accumulation and EL. In this experiment, SA treatment, with enhancing growth Rate and changing physiological parameters decreased adverse effects of drought stress on lettuce plants.