Effects of salicylic acid on seed germination and biochemical properties in seedlings of Lactuca sativa L. under high temperature stress

Effects of salicylic acid (SA) on seed germination and biochemical properties in seedlings of Lactuca sativa var. crispa L. ('Rapid') under high temperature stress were studied. Results showed that SA of appropriate concentrations (0.2 mmol center dot L-1) significantly improved the germination rate, germination potential and seed vigor index when incubated under high temperature stress condition (35 degrees C/30 degrees C, day/night). SA enhanced the activities of POD, CAT and SOD and the contents of proline and soluble proteins, as well as reduced the MDA content. Both the seed germination properties and biochemical characteristics indicated that the treatments would be less effective when SA concentration was over 0.4 mmol L-1 or below 0.2 mmol L-1.