Effects of PAR intensity and NaCl concentration on growth of Salicornia europaea plants as relevant to artificial ecological systems

Abstract

Effects of variable levels of photosynthetically active radiation (PAR) and NaCl concentrations, typical of closed ecological life support systems, on growth of Salicornia europaea L. plants, CO2 exchange, mineral composition, and the content of malondialdehyde (MDA) and photosynthetic pigments were investigated. The plants were grown for 25 days at different salinities of nutrient Knop solution (171, 342, and 513 mM NaCl) under two PAR levels (690 and 1150 μmol/(m2 s)). At PAR of 690 μmol/(m2 s), the plant productivity did not show significant changes at increasing salinities; at 1150 μmol/(m2 s), the maximal productivity was observed at NaCl concentrations of 171 and 342 mM. The increase in NaCl concentration from 171 to 513 mM in the nutrient solution led to a substantial increase in the relative Na content in aboveground organs at PAR level of 1150 μmol/(m2 s). The MDA content in aboveground organs by the end of the growth period was independent of PAR intensity. The content of photosynthetic pigments in the assimilatory tissue decreased with the increase in salinity from 342 to 513 mM NaCl at PAR level of 1150 μmol/(m2 s) but not at the lower irradiance. The combination of 1150 μmol/(m2 s) PAR intensity with the salinity as high as 342 mM NaCl was found to be the most effective for optimal productivity of S. europaea plants.