Investigating the physiological mechanisms underlying Salicornia ramosissima response to atmospheric CO2 enrichment under coexistence of prolonged soil flooding and saline excess

A 45-days long climatic chamber experiment was design to evaluate the effect of 400 and 700 ppm atmospheric CO2 treatments with and without soil water logging in combination with 171 and 510 mM NaCl in the halophyte Salicornia ramosissima. In order to ascertain the possible synergetic impact of these factors associate to climatic change in this plant species physiological and growth responses. Our results indicated that elevated atmospheric CO2 concentration improved plant physiological performance under suboptimal root-flooding and saline conditions plants. Thus, this positive impact was mainly ascribed to an enhancement of energy transport efficiency, as indicated the greater P-G, N and Sm values, and the maintaining of carbon assimilation capacity due to the higher net photosynthetic rate (A(N)) and water use efficiency (iWUE). This could contribute to reduce the risk of oxidative stress owing to the accumulation of reactive oxygen species (ROS). Moreover, plants grown at 700 ppm had a greater capacity to cope with flooding and salinity synergistic impact by a greater efficiency in the modulation in enzyme antioxidant machinery and by the accumulation of osmoprotective compounds and saturated fatty acids in its tissues. These responses indicate that atmospheric CO2 enrichment would contribute to preserve the development of Salicornia ramosissima against the ongoing process of increment of soil stressful conditions linked with climatic change.