Salicylic Acid Decreases Salt Stress Damage on Photosynthetic Processes and Increases Essential Oil Content in Basil ‘Cinnamon’

Salt stress can cause several damages to photosynthetic processes of Ocimum basilicum ; however, it can increase the essential oil content as an acclimatization strategy to stress. The application of salicylic acid (SA) may be a strategy to decrease the damage caused by salt stress. Thus, the objective was to evaluate the application of five doses of SA as a mitigator of salt stress damage at different levels and as an inducer of essential oil content in O. basilicum ‘Cinnamon’. Plants were grown with five water electrical conductivities (0.5, 1.3, 3.25, 5.2, and 6.0 dS m −1 ) and five SA doses (0, 0.29, 1.0, 1.71, and 2.0 mM). Gas exchanges, chlorophyll a fluorescence, chlorophyll indices, plant dry mass, and essential oil content were evaluated. SA application decreased salt stress damage on gas exchange (gs, A, E, Ci, WUE, and iWUE), chlorophyll indices and chlorophyll a fluorescence. Salt stress decreased the growth (total dry mass) of O. basilicum plants, and SA was not able to decrease the stress damage in this variable. The application of SA and salt stress increased the essential oil content of O. basilicum ‘Cinnamon’. The use of SA combined with salt stress is a strategy to increase the essential oil content of O. basilicum ‘Cinnamon’, especially in semi-arid regions.