Salicylic acid mitigates salinity effects by enhancing the growth, CO2 assimilation, and antioxidant protection in Jatropha curcas plants

The effects of salicylic acid (SA) and salinity on growth, photosynthesis, and antioxidative protection were studied in the leaves of Jatropha curcas. Twenty-three-day-old plants were exposed to 0 (control) and 100 mM NaCl and sprayed with 5 mM SA. The salinity treatment reduced the growth and gas exchange parameters of the species, but when the exogenous SA was applied to these plants, it mitigated the adverse effects of salinity. Similarly, the salinity stress decreased the activities of ascorbate peroxidase and catalase and increased the hydrogen peroxide contents compared to controls; however, after application of exogenous SA, the activities of theses enzymes increased with a concurrent decline in ROS-accumulation. In summary, our results demonstrated that SA mitigates the effects of salinity by enhancing the growth, CO2 assimilation, and antioxidative protection.